[HN Gopher] Heat pumps of the 1800s are becoming the technology ...
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Heat pumps of the 1800s are becoming the technology of the future
Author : adrian_mrd
Score : 109 points
Date : 2023-01-16 06:59 UTC (16 hours ago)
(HTM) web link (knowablemagazine.org)
(TXT) w3m dump (knowablemagazine.org)
| mikewarot wrote:
| For our house, a ground loop heat pump would be best. A long slit
| trench, with the slinky style of coolant loop, in the back yard
| (away from utilities) could easily handle all our waste heat in
| the summer and source heat in the winter.
| ddalex wrote:
| Wouldn't it be cheaper/easier to dig a well, fill it with
| tubing, and pouring concrete all over? The concrete being the
| constant-ish temperature heat reservoir ?
| Nextgrid wrote:
| Would concrete have sufficient thermal conductivity compared
| to damp soil?
| richjdsmith wrote:
| My parents built a new home a couple years ago. The property
| had a well despite being on city water. They have other homes
| with ground source heat pumps. When asking the geothermal
| contractor if they could use the same well borehole, the
| contractor said why don't we just circulate the water and not
| bother the existing well. So that's what they do - their
| geothermal system uses the well water, circulates it through
| the condenser, then sends the water back down into the
| ground.
| voisin wrote:
| This is fascinating! Is it possible to do this while
| utilizing the well for drinking water? I would assume so -
| it would just go through the condenser to exchange heat
| before being used elsewhere, and less would be pumped back
| down to the well?
| smm11 wrote:
| Holding my breath that my firebreathing gas stove is actually
| okay with The Man.
| dv_dt wrote:
| Thermodynamics is eternal
| rini17 wrote:
| Interesting! Do I understand correctly that the additional water
| storage just cycles between 0degC and below room temperature to
| further cool/preheat the coolant? Hard to believe it could have
| such a big effect.
|
| And how does it fit into existing setup? I can imagine it can be
| connected before water boiler to supply the lukewarm water.
| BooneJS wrote:
| When will air source heat pumps be ready for service in cold
| weather climates without gas backup?
| cbrozefsky wrote:
| They are now.
|
| In Vermont, we are in our first year with heat pumps. Have a
| wood stove as backup and supplement when we want to go
| pantsless mode. The original oil burner is currently turned
| off, out of commission waiting on some parts. We could go
| without the wood stove, and have done so for stretches.
|
| We installed Mistubishi Hyperheats, 3 external units, 5 heads.
| Zero interest financing by installer, for about 21k all in
| including electrical work. Earlier this year we also did air
| source hot water heater, for about 4k all in.
|
| We were spoiled by the whole house air conditioning over the
| summer, and the heating has been performing just fine. It about
| doubled our electric consumption, but that bill is still less
| than my oil bill was, before the price of oil nearly doubled.
|
| We're motivated primarily by a desire to minimize fossil fuel
| consumption, and then to mitigate volatility in fossil fuel
| markets. With this install we completed electrifying all
| utilities in the house , and have a rooftop solar array that
| previously offset the entirety of our consumption, but will not
| at current levels.
|
| The heat pumps will just about pay for the cost difference
| between them and a new oil burner before their parts warranty
| is up. Add in the cooling, and the increased control and
| comfort we have, and it's a pretty sound investment, IMO.
|
| As an anecdote, the conversation at the local bar in Rutland,
| VT the other night was all about people planning to get heat
| pumps, or promoting them after having them installed. Not
| wealthy tech enthusiasts, but bartenders, small business
| owners, and working class families. With the IRA inventives,
| and the price of heating oil -- it's becoming a normal thing,
| not an exception.
| fulafel wrote:
| Why doubt their existence? There have been good cold climate
| air source heat pumps for a long time, over 10 years at least.
| rr808 wrote:
| I feel a combination with a wood burning stove is best.
| Especially with the potential for power cuts.
| Scoundreller wrote:
| Wood pellet stoves are very efficient and semi-automated.
| Pellets can be cheaper than split logs (if you have to buy
| them).
| boplicity wrote:
| They're available right now -- you can get ones that will heat
| from -30c. They're less efficient at colder temperatures,
| though.
| rainsford wrote:
| It depends on what you mean by "cold weather", but modern air
| source heat pumps are getting increasingly efficient in
| surprisingly cold temperatures. This Samsung model I randomly
| found from a Consumer Reports link
| (https://ashp.neep.org/#!/product/65014/7/25000///0) claims to
| still heat almost as effectively well below freezing as it does
| at more mild winter temperatures.
|
| Even for less effective heat pumps, gas backup isn't really a
| requirement since you can often use electric "heat strip"
| backup like my home does. Heat strips are not particularly
| energy efficient, but many places that can get cold during the
| winter aren't continuously cold, so a less efficient electric
| backup is just fine.
| dabeeeenster wrote:
| Just had a heat pump installed (Vaillant) - at -1 degrees
| outside I'm getting a COP of > 2.6.
|
| So they are ready.
| sampo wrote:
| > -1 degrees outside
|
| -1F is -18C
|
| -1C is 30F
| ComputerGuru wrote:
| They're from London, so it's the "not even cold but it's
| negative" rather than "actually cold and heat pumps aren't
| a good idea" measurement.
| Freestyler_3 wrote:
| for those places where the scop is low, you have to drill
| for heat. If that's not possible then maybe a system
| where you can burn wood to suck the heat out of that.
| nickpeterson wrote:
| Why can't my whole home participate in this technology? It would
| seem an ok fit for things like freezers, refrigerators, hot water
| heaters, etc.
|
| When it's freezing cold outside, it seems crazy that I warm the
| air of my house and then use electricity to keep the fridge
| cooler than the air I just heated.
|
| Someone needs to make a standard for moving heat/cool through all
| appliances in a house...
| jillesvangurp wrote:
| The good news is that the process of running your fridge moves
| the heat from the fridge into your home, which in the winter is
| not such a big problem. Your fridge is just another heat pump.
| It's a bigger problem in the summer when you are maybe trying
| to cool your house using air-conditioning and your fridge adds
| heat to your house to keep the fridge cool. Much less
| desirable.
| coffeebeqn wrote:
| Simple- just keep the fridge doors open during the summer
| naijaboiler wrote:
| actually, that makes the room warmer. Your fridge just
| becomes a bigger heatpump with the door open. the
| compressor has to work hard to cool a larger area, so
| therefore uses more electricity and dumps more heat out
| into the room.
| elil17 wrote:
| You'd need one of three solutions to make this work:
|
| 1) Long refrigerant pipes. This is unacceptable because it
| increases the amount of refrigerant in the systems (refereed to
| as the charge of the refrigerant). Refrigerants are powerful
| greenhouse gases so it is important to design low charge
| systems.
|
| 2) Another process fluid (e.g. water or glycol). This adds
| expense (more pumps and heat exchangers). You'd increase the
| cost of all these systems by a lot.
|
| Also, both 1 and 2 involve running a new set of single use
| pipes around your house.
|
| 3) Make a "single appliance" household. A design like this has
| been tried - single AC/heat pump hooked to fridge, freezer,
| oven, dishwasher, washer/dryer, and water heater. The problem
| is that you really have do design the house around this and it
| is quite limiting from an architectural perspective.
|
| Combined AC/heat pump and water heater is a thing though.
| kortex wrote:
| Adding to (2), I've worked with liquid-liquid heat exchangers
| (large heat/chiller units for chemical reactors) and they are
| super quiet and efficient, but boy howdy, are they messy and
| high maintenance. The glycol lines leak, the water supply
| leaks, the water needs to be screened and the screen needs to
| be changed.
|
| Air-sourced exchanger individual appliances are just so much
| simpler for the consumer.
|
| Not dissing ground-source heat pumps. Those are fine, since
| they are typically a plumb-once-and-done. You just generally
| don't want separate appliances which quick-connect.
| floxy wrote:
| I think you are going to like section IV of:
|
| https://bayes.wustl.edu/etj/articles/AJP00180.pdf
| rpearl wrote:
| There are heat pump water heaters (I have one; AO Smith
| HPTU-50N). More expensive up front vs tankless but a lot more
| efficient.
| Scoundreller wrote:
| Depends on usage. Tankless efficiency really shines with
| irregular use.
|
| Keeping a big reservoir warm for the sake of keeping it warm
| only becomes efficient with regular usage.
| teruakohatu wrote:
| Tanks can be heated at night (or midday), when electricity
| is cheaper and, in my case, when non-renewables are
| contributing less to the grid.
| 1ris wrote:
| I think you are looking for (one specific implementation of)
| Cold district heating.
|
| It can be implemented as a single line of force water flow with
| 20-25 Celsius. It is viable as both a heat source and a heat
| sink at the same time.
|
| This thing can be connected to both your coolers and heaters,
| and thus transfere heat from one to another. Maybe you could
| even get you desktop computer into the loop.
|
| Usually it implemented on a lager scale, but i don't see why
| this would work scaled down.
| mschuster91 wrote:
| > Why can't my whole home participate in this technology? It
| would seem an ok fit for things like freezers, refrigerators,
| hot water heaters, etc.
|
| At large scale (think like walk-in coolers of supermarkets),
| this is actually being done in the form of district cooling
| [1].
|
| > Someone needs to make a standard for moving heat/cool through
| all appliances in a house...
|
| The problem is that the piping itself and the circulation
| required are sources of energy loss, and it's hard enough to
| keep these appliances sealed so they don't leak their coolant -
| most coolants have _insane_ CO2 equivalent potentials. It 's
| not worth the effort.
|
| [1] https://en.wikipedia.org/wiki/District_cooling
| homero wrote:
| Your fridge is already doing it. It's heating your house
| phkahler wrote:
| The fridge is heating your home, so that reduces the burden on
| whatever is heating your home. The coil on the back gets hot.
| teruakohatu wrote:
| > The fridge is heating your home
|
| Not really, efficienty aside the heat it puts out the back is
| coming from inside the fridge... Which is coming from the
| room housing the fridge. So over the course of a day it
| should be neutral.
| [deleted]
| tiagod wrote:
| The heat is coming from the inside of the fridge and from
| the power used. It's net positive heat.
| blacksmith_tb wrote:
| Note that this is only an advantage in cooler months, and
| does work against cooling your home in hotter weather. In
| principle it seems like we could could build our
| refrigerators into an outside wall (like iceboxes once were)
| and then expose the coils in summer, and enclose them in
| winter.
| AlanSE wrote:
| The fridge isn't the biggest energy hog in the house, but I'm
| very sympathetic to the absurdity of heat levels in a house.
|
| I often see my HVAC cooling when the set-point temperature is
| actually _higher_ than the outside temperature. Logically, the
| house is a heat generator, it makes sense physically. The roof
| is black, etc.
|
| It would offer a good number of benefits if the system could
| outright open a duct to the outdoor air, and suck it in
| whenever the local outside temperature is within the range
| requested by the user. People who are into optimizing energy
| use (they exist) can go even further and pre-cool their house
| during the night in summer.
|
| For this to work, all you need a pusher fan, no refrigeration
| at all. There might be some pressurization problems, like, you
| may need a duct both for the intake and outlet. Also might
| require another filter... but air quality would improve
| significantly.
|
| This is a really "dumb" idea, but it's perfectly in-line with
| all the new ideas being thrown out there. The new ideas just
| tend to throw in an additional heat storage mechanism, like a
| water tank (in the article). You can get a lot more efficiency
| gains by saving the night's cold in a tank and using it through
| the day. But on a more basic level, you can pump straight into
| the house when the conditions are right.
| elil17 wrote:
| That exists, it's called an air-side economizer. It's used a
| lot on big buildings.
| ComputerGuru wrote:
| I've built/retrofitted and a prototype of mechanically
| operated louvres with push/pull fans for air exchange in an
| old school building, tied to the thermostat, ac, and a CO2
| detector.
|
| The idea of doing the same in my home has been taunting me
| for years now. Ideally you'd have two such louvres, one with
| a push fan in the upper floor and the other with a pull fan
| in the lower floor to simultaneously eject unwanted heat,
| bring in fresh air, and boost whole-house circulation. They'd
| be set up to interface with the thermostat/hvac and would
| operate when the outdoor temperature at intake is lower than
| the temperature at exhaust and both are above the set point
| on the ac.
|
| The biggest problem is really one of convenience. You'd need
| a filter on the intake and a rather large and powerful fan to
| overcome that static pressure - ergo, a noisy one. And you'd
| probably have to fully dismantle the system in the winter to
| prevent the cold from getting in (the Midwest is cursed with
| both hot and humid summers and cold and dry winters). It just
| end up being the kind of thing where the devil really is in
| the details and you either do it right and it's a huge
| undertaking or you do it fast and sloppy and its drawbacks
| won't be worth it.
|
| But I agree, nothing is more infuriating than seeing the AC
| on and the outdoor air temperature being lower than that of
| the home. And opening windows just doesn't make a difference
| since in most 20th century homes there's just poor airflow
| and no circulation.
| mixmastamyk wrote:
| > But I agree, nothing is more infuriating than seeing the
| AC on and the outdoor air temperature being lower
|
| Won't cooler temps outside make the AC work more
| efficiently and get to the desired temp more quickly?
| Scoundreller wrote:
| I was thinking a big vertical heat pipe that sticks out
| like a chimney would be great for this and keep
| inside+outside sealed.
|
| When it's colder outside, liquid will evaporate on the
| bottom and condense at the top through gravity. Once it's
| warmer outside, the whole process just stops.
|
| No valves, no pumps, no analog or digital controls. Ok,
| maybe a fan.
|
| I actually want a fridge/freezer at the cabin that works
| like this in fall/winter/spring. I know it's technically
| moving heat from inside to outside, but I've got more wood
| than electricity to work with.
| landemva wrote:
| Whole house fans are often used in summer at dusk to
| rapidly cool house. Air is sucked through house into attic,
| which also cools the attic.
|
| https://www.thespruce.com/whole-house-fan-vs-attic-fan-
| diffe...
|
| Crack open a window downstairs before switching it on.
| stuaxo wrote:
| Sounds like you are describing an MVHR system?
| Tijdreiziger wrote:
| What would the upside be over a standard heat-exchanging
| mechanical ventilation system?
| cypherpunks01 wrote:
| You are exactly describing a HVAC "Economizer" as they are
| called. I believe they are almost solely used in commercial
| HVAC installs, probably due to price/additional install
| complexity? They are very neat though, and do save
| significant energy in shoulder seasons, or at night in the
| summer as you mention.
| ballenf wrote:
| I've often wondered if opening windows while AC is running
| and outside temp is below inside temp is less efficient than
| keeping them closed.
|
| My thought is I should keep them closed due to extra load on
| the AC to dehumidify the outside air. Or open windows and
| turn AC to fan-only mode to prevent stagnant air in rooms
| without windows.
| jdmichal wrote:
| Unless you have a very strange setup, centralized A/C does
| not have humidity sensors nor run just to dehumidify. Nor
| does removing humidity increase the load on the A/C system.
| Removing humidity is just a happy by-product of how
| centralized A/C works. So no, you would not be increasing
| load for that reason.
| TeMPOraL wrote:
| Happy in some times, unhappy in others. There are days
| I'd love if the A/C would have a humidifier built-in, for
| those winter months when you might want to use A/C to
| _warm_ the interior.
| nemo44x wrote:
| HVAC can do that and it's not too expensive. You do need
| to run water to your unit though and there's quite a bit
| of maintenance as humidifiers create mold, etc.
| pixelcort wrote:
| One of the Daikin models for Japan apartments/condos
| (known as mansions) has a tankless humidifier; it is able
| to condensate humidity from outdoor air and introduce it
| into the home. On a cold winter day it is able to raise
| the relative humidity from around 30% to about 45% or so.
| ururutosarara is the name of their series of things that
| humidify.
| ComputerGuru wrote:
| A good chunk of the United States (and a number of other
| countries) uses forced air natural gas heating. If you
| fall into that group, you can install a "whole-house
| humidifier" that injects steam into the hot air plenum,
| distributing it around the house. This makes the air less
| dry (obviously) but also has the side-effect of actually
| reducing the need for heating because air holding
| moisture _feels_ warmer than air without (hence the
| oppressive heat in the humidity of summer), meaning you
| can lower the thermostat.
|
| Unfortunately I have only seen commercial humidification
| units that boil water into steam with the use of natural
| gas. Without exception, everything for sale for home use
| uses electricity (you'll need 230V minimum, single phase
| will do just fine) to boil the water, which is _costly_
| (though this year natural gas prices have risen or even
| doubled, but even in states with cheap electricity it 's
| probably still cheaper to use natural gas).
| mmaurizi wrote:
| We run our steam humidifier just fine on 120v, but we
| have a relatively small townhome at 1400sqft
| ComputerGuru wrote:
| Be careful you're not running it independently of whether
| or not the furnace is actually on. 120V generally can't
| evaporate enough water in the short window while the
| furnace is running and many techs will set it up to run
| at all times (with the blower but not the furnace) to
| compensate. This lets mildew or mold grow in your ducts.
| landemva wrote:
| I had one that dripped water through a pad in air flow,
| and had a small drain pipe. Maybe not as good as steam,
| though much simpler.
| Scoundreller wrote:
| The ones I've seen have a rotating foam drum pad in a
| small reservoir of water that refills like a toilet tank.
| SoftTalker wrote:
| The moisture can promote mold in the ductwork though. We
| had our furnace replaced a few years ago and had the
| central humidifier removed. The interior of the ductwork
| was black with mold near the humidifier so that was also
| replaced.
| tshaddox wrote:
| Based on some of the home building and HVAC videos I've
| seen on YouTube, it seems pretty common for high-end new
| home construction in the U.S. (especially the south) to
| have separate AC and dehumidifier units.
| Volundr wrote:
| FWIW I had a new Lennox heat pump installed a couple
| years ago, and I can (but don't) configure it to "cool to
| dehumidify", and it tells me the humidity on the
| thermostat. I don't know if this is common in new units,
| or if I'm just special.
| elil17 wrote:
| The above comment is incorrect, even for systems without
| integrated dehumidifiers. AC systems absolutely do have a
| higher load with higher humidity because ambient water
| will condense on the evaporator coils if the dewpoint is
| higher than the evaporator temperature (which it
| typically is).
|
| That said, it still may be more efficient to open your
| windows, depending on the humidity.
| [deleted]
| JustSomeNobody wrote:
| My thermostat allows me to set the humidity level at
| which it will turn on the A/C to deswampify my southern
| home.
| soco wrote:
| Is the AC dehumidifier an extra feature/task, so actively
| followed, or is it doing dehumidification just as a
| byproduct happening while cooling?
| yetihehe wrote:
| Some AC units have two modes - cooling and dehumidifying.
| When in cooling mode it will blow a lot of air to keep
| evaporator as hot as possible, so less humidity is
| condensing on it (but there will still be some). In
| dehumidifying mode it will blow less air but keep
| evaporator cool, so more condensation for the same amount
| of air cooling.
| rstupek wrote:
| It's a byproduct of the process of cooling the air
| wffurr wrote:
| You are looking for a ventilation system like a HRV.
| rr808 wrote:
| Pool heater too. In our building we have massive AC units and a
| separate heat pump to warm the pool.
| cinntaile wrote:
| That sounds like it would be very expensive and error prone.
| retrac wrote:
| > it seems crazy that I warm the air of my house and then use
| electricity to keep the fridge cooler than the air I just
| heated
|
| The fridge is simply moving a little of the warmth in your room
| out of its box, and adding a little more warmth to the room in
| the process. You lose no heat from the room, which is what
| matters, really. It would be worse to dump the heat outside! At
| least in winter. The heat has to be removed in summer if you
| have air conditioning.
|
| In any case, an exterior heat exchanger and heat pump that can
| handle a wide exterior temperature is much more heavy duty.
| This could all end up being less efficient, in practice. House-
| scale heat pumps can efficiently move heat even from a freezing
| cold outside into a warm interior. Just as fridges can
| efficiently move heat from their cold interiors to a warm room.
| ghettoCoder wrote:
| I always joke that in winter all appliances are 100%
| efficient (I know they're not). Some look at me funny but the
| ones who pay the gas bill get usually get it.
| ComputerGuru wrote:
| This is the first year where heating the home with gas
| isn't an order of magnitude cheaper than with electricity
| here in the Midwest. Gas still wins, but not by as large of
| a margin!
| elil17 wrote:
| If you have a resistance electric furnace, that is
| essentially true. With gas, you add the electric generation
| and distribution losses, which is a pretty big difference.
| It does cost more to run an appliance than to heat with
| gas.
| ClumsyPilot wrote:
| Gas boilers produce NO2, and other nasties - they do
| affect air quality in your house
| kwhitefoot wrote:
| How do they affect the air quality indoors? Don't modern
| (less than fifty years old) gas boilers have balanced
| flues so that they take in air from the outside and
| exhaust the combustion products outside too?
|
| Surely properly installed gas boilers always did that
| even without balanced flues too.
| abakker wrote:
| My experience (sample of one) is that they don't. They're
| supposed to, but VOCs are definitely higher all winter
| running heat than all summer running air conditioning.
| Natural gas combustion is at best _mostly_ exhausted.
| elil17 wrote:
| It could also be that outdoor AQ is worse around you in
| the winter because everyone is running their boilers, and
| then that outdoor air ends up inside. I can't test it
| because I have a heat pump, but I would be curious to
| know what happens to your VOCs if you turn off your
| boiler at a time when your neighbors are still running
| theirs.
| ezzaf wrote:
| If you account for the electric generation and
| distribution losses, you should do the same for gas.
|
| "It does cost more to run an appliance than to heat with
| gas."
|
| That's highly dependent on the appliances involved and
| the price you pay for each fuel. For me, a heat pump is
| much cheaper to run. You really need to calculate it for
| each individual situation.
| kibwen wrote:
| Of course, by the same token, in summer their efficiency is
| less than you expect since you need to consider the
| additional burden on your AC.
| tonyarkles wrote:
| And incandescent light bulbs!
| galangalalgol wrote:
| Resistive heaters lile a lightbulb are much less
| efficient than a heat pump. You'd still be better off
| with the led.
| elil17 wrote:
| No, because the light can escape through windows.
| maxk42 wrote:
| So can heat. That's not the appliance's fault.
| elil17 wrote:
| It's not about fault at all - I'm just saying that the
| analysis does not apply to lightbulbs. For a lightbulb to
| be as efficient as a resistance furnace at heating a
| room, you would need to have zero light escape that room
| so that all the light would be converted to heat. Then,
| the heat would leave the room at the same rate as heat
| generated by a resistance furnace.
|
| Even if we consider incandescent light bulbs, which waste
| most of the energy they use as "heat", that heat is
| actually being transferred primarily through radiation,
| so it can escape through windows more easily than the
| heat that a furnace transfers to your indoor air.
| stuaxo wrote:
| The heat isn't where you want it.
| vanviegen wrote:
| I think 100% is pretty accurate for most devices, except
| for washing machines and other gadgets connected to the
| sewer. Where else would the energy go?
|
| Your fridge has the potential to go even higher than 100%,
| as it's a heat pump. But for more than a temporary effect
| you'd have to keep replacing the stuff inside it with stuff
| warmed up to outside temperate, which would have to be
| between fridge temperature and room temperature. Perhaps
| slightly impractical.
| tshaddox wrote:
| "100% efficient" doesn't tell the whole story of the gas
| bill if you're heating your house with something cheaper
| than electric heat (e.g. natural gas).
| stuaxo wrote:
| The back of my fridge is in a really confined space, like
| many fridges - that heat would be better taken somewhere
| else.
| Scoundreller wrote:
| The smart thing to do in winter is put municipal liquid water
| in your freezer, and dump it outside once frozen to thaw in
| spring. Rince repeat all winter long.
|
| Voila: everyone has heat pump heating! (And dead
| compressors).
|
| The dumb thing is having the compressor itself indoors in
| summer. Should be outside.
| bobthepanda wrote:
| The issue with that is that if it's outside, you need a
| hole in the wall somewhere to connect it.
|
| Today fridges are more or less plug and play. Most kitchens
| don't have a hole in the wall going outside where the
| fridge would go. Some kitchens aren't even on walls facing
| the exterior (which I dislike, but they exist)
| mixmastamyk wrote:
| Interesting, how to remove it easily from the container? Or
| do you use an ice machine? Is this more efficient than
| using the heater? Guess it uses heat pump tech.
| IMTDb wrote:
| In order to cool your refrigerator, the system has to have a
| place to the put the "hot" it just extracted. And that place is
| your house itself; your freezers and refrigerators are warming
| your house and contribute just like the radiators you
| installed. So the losses are not as big as you expect them; the
| money you spend on those appliances also lowers your heating
| bill.
| spookthesunset wrote:
| > the money you spend on those appliances also lowers your
| heating bill.
|
| It should net out to no less than the same energy though,
| right? That refrigerator needs energy to move the heat out of
| the fridge and into the home. If that process takes more
| energy than just letting the house HVAC deal with it,
| wouldn't the energy bill be higher?
| ChainOfFools wrote:
| Devices are beginning to appear that can move the waste heat
| generated by home AC compressor into the pump loop for a
| swimming pool outside that same home, getting your pool heated
| for free by cooling your house, and your aircon cooling
| becoming much more efficient by using your swimming pool as a
| giant heat sink.
|
| However unless the house was built, and / or the pool installed
| in a coincidentally fortunate configuration where the AC
| compressor and the pool filter pump are within a meter or two
| of each other, these devices cannot be used effectively due to
| impractical tolerances and insulation needed to mitigate losses
| from contact with the highly variable outdoor environment.
| azdle wrote:
| It is technically possible. I had the same thought as you and
| looked into it some time ago. The only references I ever found
| to it actually being implemented were in cases of giant walk-in
| (even warehouse sized) refrigerators/freezers in places where
| district cooling exists.
|
| For something the size of a home fridge the costs would be
| immense compared to the energy savings. You're far far better
| off spending that money on more efficient heat pumps and
| more/better insulation.
|
| The federal limit for the amount of power a fridge can pull is
| 527 kWh/year, which at my rates (admittedly on the low end
| these days) is ~$70/year. There are very commonly available
| fridges that are < 300 kWh/year, which would be ~< $40/year. So
| before even taking into account the efficiencies you implicitly
| make back when you're heating your house anyway, that's your
| per-attached-appliance limit for input cost on building out,
| maintaining and running that system.
|
| Though, I admit that the idea of a completely silent fridge &
| A/C is alluring. Here's to hoping we make some breakthroughs on
| sold-state heat pumps.
| elil17 wrote:
| Here's a research paper detailing a design for your idea: htt
| ps://www.sciencedirect.com/science/article/abs/pii/S03605...
|
| It was never pursued further for reasons I discussed in
| another comment on this thread.
| phyzome wrote:
| > owners of drafty homes may need to take on the added cost of
| insulation when installing a heat pump
|
| Installing good insulation is also really important even if
| you're not using heat pumps! With bad insulation, you're wasting
| energy no matter what technology you're using.
| nostrademons wrote:
| I've heard folks who work in the home energy audit business say
| that upgrading insulation is usually the most cost-effective
| thing you can do to lower energy bills. Even better, it's
| multiplicative with other activities like installing heat pumps
| or solar, so you can install a much lower capacity system and
| still hit your energy targets.
| lll-o-lll wrote:
| If you live in a warm climate, I personally think insulation is
| the worst (excepting roofing). Not because of efficiency, but
| because you isolate yourself from nature! The traditional
| Queenslander (look up Bluey if you don't know what I mean), has
| so much going for it. It allows airflow through the whole
| house, a protected outside to sit and be with nature, lizards
| coming and going, bliss!
|
| This hermetically sealed environment that we create for
| ourselves is bad for us.
| nomel wrote:
| Insulation can be orthogonal to fresh air. Ventilation energy
| recovery units [1] exist to help reduce loss from fresh air
| (and are code for new houses where I am). This has the
| benefit that you can have _more_ fresh air, for the same heat
| loss, since the loss will be from the fresh air, rather than
| through high thermal conductivity through the non-breathable
| portions of the walls.
|
| 1. https://en.wikipedia.org/wiki/Energy_recovery_ventilation
| darknavi wrote:
| That can work just fine by intentionally opening windows.
| Having a "drafty" house is just forcing that 100% of the time
| (which isn't always wanted).
|
| Side note: As a US resident in an area with a ton of
| mosquitos, I cannot understand why other countries don't
| heavily use window screens. Lizards a pretty cool, flies and
| other flying bugs are just annoying and gross.
| nemo44x wrote:
| It's not always possible. For instance old wood double hung
| sash windows require a weight box to work. Those boxes can't
| really be insulated. And there's a good chance you don't want
| to replace the old windows (or possibly can't due to historic
| restrictions) because they are a massive part of the homes
| character.
|
| Also insulating an old home (pre-WW2) could begin to introduce
| moisture issues in the walls that weren't there the last 100+
| years since the leakiness of the home would dry the structure.
| Last thing you want is for condensation and water vapor to
| build up in the insulation and then begin to rot the wood.
| Modern build have vapor barriers and airtight seals.
|
| I guess my point is to be careful with old structures without
| considering things. They were built the way they were because
| those were the materials we had (old growth wood!) and they
| were designed to function a certain way.
| fifteenforty wrote:
| In a house I own in Melbourne, Australia, I just replaced an old
| gas central heating system with 3 new top of the line Daikin mini
| split heat pumps. The new units can heat the entire house for the
| same amount of electrical energy that was used to run the FAN in
| the old gas unit. They are crazy efficient.
|
| Ducts are dead.
|
| The Daikin Alira X is the gold-plated option and cost $8k AUD for
| 2x2.5kw and 1x7.1kw units including installation. Payback time is
| about 3 years. The system is oversized, but enables excellent
| zoning and of course provides cooling which is a must on 40C/104F
| days.
|
| Why do they seem to be so much more expensive in the US?
| throw0101a wrote:
| > _Ducts are dead._
|
| Ducts are still needed to circulate air, especially if you want
| to remove stale air (e.g., bathrooms, kitchen) and bring in
| (filtered) fresh air (to bedrooms).
| dublinben wrote:
| They're obviously no replacement for exhaust fans in
| bathrooms and kitchens, but there's a number of ductless
| energy recovery ventilators that can give you fresh air in
| your bedroom(s).
|
| https://www.buildwithrise.com/stories/ductless-heat-recovery
| kccqzy wrote:
| Not being snarky but why don't you just open the window for
| that?
|
| I have a CO2 detector that I believe is a reasonable proxy
| for stale air. When it goes above 1000 I simply open the
| windows. By the time I remember to close the windows the
| reading is almost always below 500.
| jahewson wrote:
| I used to have a bathroom without an extractor and in the
| winter with the window open the cold air would just cool
| the walls and cause more condensation there than I'd get
| with it closed.
| adrianmonk wrote:
| Allergies, humidity, heat, cold, rain, noise, privacy, and
| the hassle of doing it manually.
| krageon wrote:
| A ventilation system allows you to filter (not a luxury
| when you live in a big city, where you will be breathing
| pollutants otherwise) or perform some thermal magic if the
| outside air is very cold (or very warm), by running the
| outflow and inflow pipes really close to each other.
| jwcooper wrote:
| Where I live, it can get very cold. Not always very
| efficient to open windows for 5 months out of the year.
|
| A great option for keeping CO2 levels down in a house is
| with an HRV (or ERV) [1] that will heat the fresh air
| coming in to cycle it throughout the house.
|
| [1] https://en.wikipedia.org/wiki/Heat_recovery_ventilation
| WestCoastJustin wrote:
| On the west coasts of Canada (BC) we've had insane forest
| fires the past few years and you 100% want to filter the
| internal air when it's extremely unhealthy outside. We're
| talking air quality index in the 300+ range or off the
| charts at times [1]. Plus, we've had these heat domes were
| it's in the high 30+ and just gross inside, where you
| really want to open the windows, but you're letting in tons
| of pollution. Basically, you need to cool off and filter
| the air at the same time.
|
| [1] https://www.airnow.gov/aqi/aqi-basics/
| nemo44x wrote:
| Part of it is code. Make-up air systems need a duct for
| example. Also a lot of people like their air filtered so
| opening a window isn't great for that. Also winter.
| mvnuweucxqokii wrote:
| Not to be snarky, but if the weather outdoors is
| uncomfortable enough to be using climate control, why would
| I want to open the window?
| kccqzy wrote:
| Because presumably in this case you would want to open a
| window for fresh air, and simultaneously run your heating
| system to heat up that fresh air?
|
| I was respond to a comment that presupposes the need for
| fresh air. If you don't need that, feel free to close the
| windows then.
| rubicon33 wrote:
| Which CO2 detector do you have?
| newmac wrote:
| Agree, ducts are wonderful! If you don't have ducts, go
| ductless for sure.
| fifteenforty wrote:
| I paid real money to have my ducts removed. They cause
| issues installing comprehensive insulation and caused
| hot/cold spots on the ceiling.
| metadat wrote:
| Honest question: Why would one care about cold or hot
| spots on the ceiling? I don't spend much time up there.
| 0_____0 wrote:
| It's still a thermal path between inside and outside, and
| thus wastes energy if you're trying to maintain an
| internal temperature that is different from the external
| temperature. Also there are radiative effects - hot spots
| on ceiling will radiate IR into your space. Just try
| standing under a corrugated steel roof in the summer.
| code_biologist wrote:
| Am I crazy, or are those two sentences completely
| contradictory?
| krageon wrote:
| I thought it was a joke. If you don't have ducts, you are
| by definition ductless. So that's how you must go.
| aclatuts wrote:
| I think he means having a duct work for the whole house
| for a central heat pump is good. But having a heat pump
| per zone is also good if you don't have ducts for the
| whole house. Some newer home designs separate heating and
| cooling from the air exchange systems so there are
| multiple zones of heating and cooling.
| aftbit wrote:
| I read it as: Ducts are better but not so much that it's
| worth tearing everything apart to install them. If you
| don't already have ducts, you should definitely use a
| ductless system. If you do have them, you get some other
| benefits.
| fifteenforty wrote:
| A recirculating central heating system doesn't do that. As
| mentioned below you either need exhaust only ventilation,
| balanced ventilation or ideally ERV/HRV. All of the above are
| available in both ducted and ductless forms.
| WillPostForFood wrote:
| >Ducts are still needed to circulate air
|
| >A recirculating central heating system doesn't do that.
|
| They definitely circulate air, and they definitely filter
| the air. Whether there is fresh air depends, mostly no.
| operatingthetan wrote:
| They may do those things, but per the other poster
| claimed they are _needed_ to do those things over a
| ductless system which is false.
| operatingthetan wrote:
| Good callout. Some people have the strangest reasons to
| hate high-efficiency ductless systems.
| teruakohatu wrote:
| > Ducts are dead.
|
| Ducted heatpumps are a thing here in NZ and make sense to me,
| not that I have used one. The heatpump sits in the roof and air
| is pushed into three or so rooms through ducts.
|
| If building a new house I think ducts would be the way to go.
| fifteenforty wrote:
| You have to think carefully about where you run the ducts.
| They can be a huge source of energy loss. 40% is the number
| quoted by the EPA.
|
| Most roofs in Australia still aren't sealed. The air barrier
| and insulation barrier is the ceiling. The roof space itself
| is not insulated, so the ducts are exposed to extreme
| temperatures, thus destroying the efficiency.
|
| Here is just one article on it:
| https://newenergythinking.com/2018/10/20/dont-use-ducts/
| Gordonjcp wrote:
| Why wouldn't you just lay insulation on the ducts, same as
| you do with water pipes?
| fifteenforty wrote:
| US and Australian units are different for insulation, but
| in my terms the insulation around the best ducts is R1.5,
| but good ceiling insulation is R6. 4x difference
|
| Edit: not to mention the huge difference in surface area.
| Ducts can expose your conditioned air to a huge, poorly
| insulated surface. Bad for efficiency.
| teruakohatu wrote:
| I hadn't considered that.
|
| My argument with split systems, at least how they are
| installed in NZ, is that they are usually installed in the
| main living area and if there is a second unit, in a
| corridor.
|
| So corridors are heated or cooled far hotter or colder than
| they need to be in order to heat/cool bedrooms.
| [deleted]
| jimmaswell wrote:
| > Ducts are dead.
|
| How do you move the heated/cooled air into/around the house
| without ducts?
| Someone1234 wrote:
| Just to add to what the other commentator said, ducted based
| systems are VERY hard to balance. It is possible using
| something called an Volume Damper, but it is uncommon (and
| adjusting them can be challenging, sometimes requiring
| removal of drywall).
|
| So people COMMONLY wind up with unbalanced floors, and people
| typically try to fix it by adjusting the vent register
| opening with mixed success.
|
| Part of the problem is that the thermostat is biased to
| wherever it is located. You can get systems with remote add-
| on temperature sensors, but that doesn't by itself adjust
| where heat/cold is being sent through a ducted system.
|
| The great thing about a Mini-Split is that you're, at
| minimum, heating each floor independently with its own
| thermostat. You can then put in e.g. interior door vents that
| simply let air pass between common areas and the rooms when
| the doors are closed.
|
| This can go even further with for example two Air Handlers
| per floor (quad units) on the east and west. So that as the
| sun moves, the correct level of adjustment can be applied to
| only the side of the floor that needs it.
| AndrewDavis wrote:
| I moved from a ducted heating house to a multi head split
| system house about 18 months ago.
|
| One of the biggest pros (in addition to the improved
| efficiency of a heat pump) is I heat and cool less space
| than i did before because i can target individual rooms.
| When i'm in my office all day I only need to heat my
| office. When it's hot and I'm struggling to sleep only cool
| my bedroom. There's no point in heating my living room^^ at
| 08:30 in the morning if i don't intend to spend time in
| there till 17:00.
|
| Sure, when it gets to 17:00 my living area might not be
| comfortable, but that can easily be overcome by turning it
| on half an hour or so beforehand (either manually or with a
| timer).
|
| ^^ I don't live somewhere where freezing pipes are a
| concern. But i'd imagine you could just set them
| differently, slightly above freezing for the rooms you
| aren't in and a comfortable living temperature in the room
| you're in.
| fifteenforty wrote:
| It's a 'mini split' in US lingo. There are thin, highly
| insulated refrigerant lines going between the outside unit
| and the inside unit. The inside unit exchanges heat with the
| air. https://www.daikin.com.au/our-product-range/split-
| system-air...
| xattt wrote:
| Since this is the top comment right now, what is integration
| with Home Assistant/Hubitat like?
| Brybry wrote:
| I don't think the hardware is that expensive in the US, it's
| the installation (which costs more than the hardware).
|
| And mistakes by installers will cost even more. Our installers
| didn't flare a line set connection properly and it leaked
| slowly and that was a very expensive bill (especially since
| refrigerants have changed so much).
|
| Our Daikin indoor units have also had condensate leaking
| issues, probably due to poor installation.
|
| Ductless heat pumps do seem like the future but I think there
| are issues with regards to condensate draining, air filtering,
| and indoor unit cleaning/maintenance and replacement that could
| be done much better.
| TheSpiceIsLife wrote:
| This is exactly the same setup I have here in Launceston.
|
| Another great thing about having three seperate units is if one
| breaks, rare as it is, you're not stuck without heating /
| cooling.
| radicalbyte wrote:
| How much electricity was the fan using? :)
| rootusrootus wrote:
| Indeed, sounds like a problem with the fan. My 3000sf house
| uses 1100W for the fan, and about 4000W for the heat pump. I
| expect converting to mini-splits would increase, not decrease
| my overall power usage.
| fifteenforty wrote:
| 700W for the gas ducted heater fan. That's the steady state
| energy consumption of all 3 units heat pumps running
| simultaneously. This is a small house of 100 square
| metres/1100 square feet.
| fifteenforty wrote:
| Obviously a new EC fan will be more efficient than a 20
| year old AC fan, but I'm talking about a retrofit
| application here.
| _benedict wrote:
| Pretty sure mini splits are significantly more efficient
| today, with SCOP of above 5, so that seems unlikely?
| fifteenforty wrote:
| This unit runs at about 5
| rootusrootus wrote:
| I recently replaced my [central, ducted] heat pump, and
| the new one is rated with a 4.981 SCOP. It's fairly
| efficient, but not the most efficient on the market.
| fifteenforty wrote:
| -40% for the duct heat loss
| renlo wrote:
| Wouldn't using a lake as a heat/cooling source cause "thermal
| pollution"? It's probably fine if a couple houses surrounding the
| lake use it, but if the technology begins mainstream enough to
| where everyone is using it, it could cause a lot of issues for
| the flora and fauna of that lake / downstream habitats.
| PinguTS wrote:
| Sorry, but I don't see any novelty here. Everything described in
| the article is commercially available. At least here in Germany.
|
| Heat pumps are used to heat a storage container called buffer, a
| water container of 200l or more of water. This is used to run the
| heat pump when energy is cheap to warm up the buffer. That is for
| example in daytime when energy is available from the
| photovoltaic. If you don't have photovoltaic you can also have a
| good energy price when running this at night.
|
| Also the storage of the heat in summer is nothing new. These
| systems are also commercially available for years. It is only
| that they are so expansive that many companies have backed out of
| those.
|
| The idea here is that in summer time you heat up a big tank in
| the ground like with a thermal system on your roof. Then in
| winter time you use that "saved" energy to run the heat pump. At
| the end of the winter the water in the tank will likely be
| freezing. That state change of the water will give an additional
| energy boost, because it is the same amount of energy you need to
| boil water. All this is well known and working and commercially
| available for years.
| sschueller wrote:
| This is like when Apple introduces some new feature that
| existed on Android for years and claims it as some sort of
| revolutionary thing. In this case it's just that the mainstream
| US has discovered heat pumps when they have been mainstream in
| Europe for many years.
| dboreham wrote:
| I lived in a townhouse in Santa Clara in the mid 1990s that
| had heat pump heating (combined with ac).
| nemo44x wrote:
| Millions of people have used them for years. They just
| weren't as popular due to gas being cheaper and available
| everywhere. There's been a bigger push the last 10 years as
| gas prices have gone up. So they've been there but it didn't
| make sense to use. You have to remember that things like gas
| are much cheaper in the USA. There's just more natural
| resources here.
| caf wrote:
| The novelty claimed is directing excess remaining heat in the
| refrigerant on the normal heating cycle, after it has passed
| through the heating coils in the house, to the buffer tank. Not
| the idea of the buffer tank itself.
| jwilliams wrote:
| Seems you're describing something a bit different? In this
| case, this energy is used to run a cycle defrost on the
| evaporator rather than run the heat pump.
| EZ-Cheeze wrote:
| "Stuck at home during the first UK lockdown of the Covid-19
| pandemic, the thermal engineer suddenly had all the time he
| needed to refine the efficiency of heat pumps"
|
| I've seen that story a few times now. The free time let a lot of
| innovation happen. Fuck jobs
| jakedata wrote:
| In 2017 we installed a very efficient air-source heat pump and
| solar panels. My electrical utility offers 1:1 buyback of
| electricity so I am able to build up a credit in the summer and
| run the heat pump well into the fall and winter on that surplus.
| The system is sized for cooling the house which means that it is
| undersized for heating, but during cool fall and spring
| temperatures it operates satisfactorily as a heat source.
|
| Our fallback is the pre-existing gas boiler which is much
| simpler, more reliable and able to be powered by a small
| generator during our all-too-frequent power outages.
|
| If I am still in this home when the current heat pump fails I
| will seriously consider a ground-source system instead. The
| ability to operate during an extended power outage is a
| significant concern and I expect to always retain the gas boiler
| as a backup.
| macinjosh wrote:
| Still waiting for one of these people who rave about their heat
| pump system to actually rely on it full time without a backup.
| Most folks could barely afford to replace an existing furnace
| in a place that has all the fixtures installed, much less pay
| to install a second one based on different setup, and then pay
| for maintaining two systems on top of everything else. It is
| absurd to think that this is a plausible way forward for anyone
| other than the wealthy tech enthusiast. Same thing for
| induction stoves. You all should start a club or something.
|
| The tech is not ready if you need a backup. I've lived in
| extreme cold climate areas and no gas furnace I've had has ever
| needed a backup.
| nagisa wrote:
| I've a 6kW nominal, ground-source heat pump as the only heat
| source. This is a well insulated building standing atop the
| soil of a European country with a temperate climate*. It does
| a great job at +35degC (passively cooling) and just as great
| at -35degC.
|
| During installation we've even made a mistake and it heated
| the building up to something like +27degC inside during early
| winter all without breaking a sweat (or my wallet.)
|
| The tech is ready. Many attempts to apply it is what's
| getting botched.
|
| * EDIT: having checked, most of europe falls within temperate
| - the country is up north.
| PinguTS wrote:
| Its always funny reading such comments while others are
| running for years their heat pumps without any problems
| needing a backup.
|
| Not only they are used in Scandinavia for years. Also in
| Germany they are used for years. The company Waterkotte
| operates since the 1980s in Germany and is a pioneer in this
| showing it is working.
|
| But there are always people ignoring the facts.
| leoedin wrote:
| Loads of countries have effective power grids which go down
| incredibly rarely. I can't even remember the last power cut I
| had - maybe a few years ago? It's certainly rare enough that
| I don't need my main source of cooking and heat to take it
| into account.
|
| My parents live in rural Scotland and use a ground source
| heat pump for heat and an induction stove for cooking. Power
| outages happen more often - but still pretty rarely. If they
| do, they burn wood for heat and eat cold food for a few
| hours.
| tomohawk wrote:
| And when the grid goes down, then what will you do? How
| will the utility compensate you for your death when they
| find you frozen?
|
| This is not an academic question, especially in North
| America. The weather here can be very harsh.
|
| We lost power earlier this year as the temparature dropped
| to 0F (-18C). Our contingency (oil heat, oil generator)
| kicked in and we were fine, but many people were not.
|
| After power was restored, people with air source heat pumps
| were still stuck, as the heat pumps don't function well at
| all at those temps, and heating up a house after it has
| cooled to a low temp is not what a air source heat pump is
| good at. These are not problems at all for an oil furnace.
| tomohawk wrote:
| The article is light on technical details, pointing to a heat
| pump vendor site for "proof" that they're great.
|
| I live in a heavily populated area with high standard of
| living, and yet we have had power outages lasting up to a
| week in the years we've lived here. Almost all in the winter,
| but also some due to hurricanes. We have have solar, which is
| great in the summer heat, but not as wonderful in the winter.
| We have air source heat pump, but also oil furnace backup.
|
| We normally run the heat pump when its above 35F, as the
| efficiency of the heat pumps drops like a rock below 40F and
| its just not worth running below 35F. The heat pump is not an
| ancient POS. It works great 99% of the time, but 1% of 365 is
| 3.65 days per year. Banking on "most of the time" to be
| alright all of the time is foolish.
|
| We have diesel generator in case of power outage, which
| allows us to run the oil furnace using the same fuel as the
| furnace. This strategy has allowed us to ride through many 1%
| case scenarios without drama.
| Symbiote wrote:
| Your normal experience is far outside what most people in
| Europe would prepare for, so our comments on this thread
| should probably be ignored by North Americans.
|
| Looking at [1], I can see only two power cuts lasting more
| than 24 hours (Barcelona, 2007 and Cyprus, 2011).
|
| Instead, "major power cut" refers to things like "The power
| cut occurred at 4:20 pm and power was slowly restored
| between 5:20 and 6:30 pm." (Glasgow, 2009.)
|
| I can't remember being without power for more than 6 hours,
| and it's probably more like 3 or 4. I've been responsible
| for some colocated servers for about 8 years, and there's
| been one occasion where grid power was lost. That was about
| 20 minutes. A Raspberry Pi I have in a village in England
| has lost power once in the last three years.
|
| [1]
| https://en.wikipedia.org/wiki/List_of_major_power_outages
| dashundchen wrote:
| I live in the snowy Great Lakes and I rely on a ground source
| heat pump and hot water heater full time. No issues at all.
| Cost similar to a high end gas furnace system when the tax
| credits were applied. Probably cheaper with air source
| systems today.
|
| I live in the city and don't lose power, but I'm hoping to
| eventually use a EV as a battery backup when the equipment is
| available and standards are finalized.
|
| A battery in a compact like the Chevy Bolt could power my
| heating system for several days.
|
| It's not like modern gas furnaces don't require power to
| operate. In a recent Buffalo blizzard power went out and many
| people with gas heating still froze and had their pipes
| burst.
| RobinL wrote:
| If gas remains expensive in Europe, it won't be absurd, so
| much as an economic no brainer to have a air to air heat
| pump, alongside a back up gas boiler. This should happen
| pretty quickly as renewables take off, and gas is no longer
| needed for electricity generation when the wind is blowing.
|
| At some point a bit further on, the backup can be simple
| direct electric heating.
| grey-area wrote:
| I know a couple of people who rely on a ground source heat
| pump without a backup in Europe. They also both have
| induction hobs as it happens!
| Volundr wrote:
| The induction comment was weird. I went from electric to
| induction a few years ago, and it's not life changing or
| anything, but it works reliability. I suppose it's faster,
| but for me the main benefit is it makes it much harder for
| me to accidentally leave a burner on and burn my house
| down.
| Volundr wrote:
| Define backup? I have a heat pump as my only source of
| cooling/heat, but it does have a single heat strip in it for
| the couple days a year it gets too cold for the heat pump
| alone. There no "second fixture" to maintain.
|
| This is common for my area.
| rainsford wrote:
| Same for where I live. And in fact it's arguably a simpler
| setup since where I live you also need air conditioning in
| the summer, so many homes already have 90% of what they
| need for a heat pump setup (which is after all just an AC
| running in reverse). Installing some other heat source
| alongside the AC you already have instead of just
| installing a heat pump for year round needs is arguably the
| more complicated option.
| jakedata wrote:
| My heat pump was a retrofit to an existing home with a
| fully functional gas boiler. Being a ductless split
| system, it did not interfere with the existing baseboard
| heat in any way. By retaining the boiler I was able to
| afford the installation of solar panels and the heat pump
| in the same year and probably reap 85% of the efficiency
| benefit for a substantially reduced up-front cost.
| rsynnott wrote:
| > Still waiting for one of these people who rave about their
| heat pump system to actually rely on it full time without a
| backup.
|
| Eh? Most new houses in Ireland have them these days (it's
| more or less the only way to meet the efficiency
| requirements). There's never a backup.
|
| > Same thing for induction stoves.
|
| Eh? Again, these are pretty standard these days, and why
| would you need a backup?
| poutine wrote:
| Different geographies have different requirements. You're
| not likely to need to face a week or more of no power after
| an ice storm in -10'C in Ireland.
| PinguTS wrote:
| We don't have power outages after ice storms.
| Temperatures of -10degC are regularly in Scandinavia as
| well as in Austria, Swiss and Germany.
|
| We are living in a developed world with working
| infrastructure.
|
| Power outages happens only by accident like when an US
| helicopter tries weird landings: https://www-abendzeitung
| --muenchen-de.translate.goog/bayern/...
| Scoundreller wrote:
| Or a crane barge not making it under the power lines
| overhead:
|
| https://www.cbc.ca/news/canada/toronto/hydro-one-
| downtown-po...
| rootusrootus wrote:
| > We are living in a developed world with working
| infrastructure.
|
| You're welcome, we bombed all your infrastructure into
| oblivion about 80 years ago, now it's all new! And also,
| your country is quite a lot denser than North America, so
| you can bury every single power cable (though you don't,
| obviously) and if you think -10C is cold, just wait until
| you see what much of North America experiences during the
| winter.
| rini17 wrote:
| There are occassional outages. But the pylons are
| designed with icing in the mind and that does the
| difference. More outages are due to poorly trimmed trees
| falling on wires than ice itself. That usually affects
| only small area and can be fixed quickly.
| Scoundreller wrote:
| Issue with the ice accretion is that when things get
| bad... they get _very_ bad:
|
| https://www.rcinet.ca/en/2017/01/05/canada-history-
| jan-5-199...
| poutine wrote:
| Sure, as I said, different geographies have different
| requirements.
| poutine wrote:
| Living in the PNW, I'm building a new house and I've chosen a
| dual fuel hybrid heat pump system as per
| https://www.bryantbing.com/products/hybrid-heat/
|
| I'll also have solar + battery. Should be able to run the
| furnace & fan but not the heat pump (too many kW/h) during a
| power outage and thus heating with gas. It'll run off the heat
| pump for 90-95% of the year, only using gas on the coldest
| days, or during an outage. To go full heat pump for 100% of the
| year you need to seriously upsize the heat pump(s) and you
| wouldn't have performance during an outage.
| nemo44x wrote:
| Why not install heated floors? That would be my choice in a
| new build.
| poutine wrote:
| It's expensive and it doesn't cool. Also doesn't circulate
| the air. I have some fancy filters and humidifiers as part
| of the system I'm putting in.
| nemo44x wrote:
| It will certainly cost more, especially since you can't
| share the venting and blower. But I'd get it quoted to
| compare. Electric systems have really come down in price
| per SqFt. Now your climate doesn't get month after month
| of freezing temperatures so maybe it won't be as dramatic
| but the energy cost savings can be huge. Plus the overall
| experience of it is the best imo.
|
| You could still circulate air with the blower running in
| fan mode and you may not need humidifiers as that's the
| biggest negative to forced air heat imo.
|
| Curious which humidifier systems you're looking at?
| pinot wrote:
| Can't heat with gas without electricity, unless you have a
| genset or power wall kind of thing to provide epower.
| poutine wrote:
| I have a sol-ark 12k which allows for grid isolation and a
| bunch of batteries.
| Scoundreller wrote:
| Since your natgas consumption is low, could a wood pellet
| heater meet your needs instead of natgas?
|
| I guess it depends if your natgas bill has a big fixed cost
| (and I guess you've already covered the sunk cost of
| connection...)
| thomasjb wrote:
| A wood pellet heater can be a fairly complex item, for a
| backup (depending on what usage frequency backup entails) a
| wood fired furnace might be more suitable if the owner is
| happy with having to add fuel every once in a while.
|
| Myself, I would like a ground source system that lets me
| store in heat from an oil fired AGA, a wood burning furnace
| and water heater panels on the roof.
| retrac wrote:
| > heat pumps: electrical devices
|
| Just to be pedantic, but not exactly. The typical design in a
| domestic heating unit, or refrigerator is mechanical. A fluid is
| pumped and cyclically compressed/expanded. While electric motors
| are usually used, they can be driven by any source of mechanical
| energy; driven directly by a combustion engine is not too
| unusual.
|
| There are also heat pump cycles that can be driven directly with
| heat. Refrigerators based on that are relatively common here in
| Canada in areas without reliable grid electricity. Usually a
| propane or natural gas flame.
|
| Thermoelectric coolers are actual electric heat pumps; directly
| moving heat across a semiconductor junction. Not very efficient
| and quite expensive practically. They're used in those USB drink
| coolers and to cool down lab equipment. Finding a high-efficiency
| thermoelectric material that works at normal temperatures and
| pressures is nearly as much of a Holy Grail as finding a high
| temperature superconductor.
| the_other wrote:
| > Finding a high-efficiency thermoelectric material that works
| at normal temperatures and pressures is nearly as much of a
| Holy Grail as finding a high temperature superconductor.
|
| Are they two sides of the same problem?
| [deleted]
| fnordpiglet wrote:
| No, TECs operates on a quirk related to semiconductor
| properties and are using electricity to move heat from one
| side to another but necessarily have resistance.
| Superconductors however are seeking zero electrical
| resistance. Current TECs produce 5x heat vs heat moved, and
| have a limited range of operation and a small range (30c) for
| the delta in heat between the two sides. I've been fascinated
| by TECs for years and I aspire to freeze CO2 with them, but
| it's actually been really difficult to get cryogenic
| temperatures. You need to build a pyramid that has
| increasingly powerful TECs drawing heat away faster than it
| can accumulate. Even then I'm hitting walls in the -30c range
| because efficiency falls off a wall at both ends as you
| exceed the optimal ranges for the semiconductor materials.
| juujian wrote:
| You are not adding anything to the conversation, but I still
| love pedantic comments like these.
| NikolaNovak wrote:
| Hmm, as somebody who knew a bit about heat pumps but not
| much, I did find it added to clarify/distinguish between the
| main mode of operation of heat pump, used to accomplish the
| actual heat transfer; and what power / mechanism is used to
| move the mechanical bits.
|
| I.e. an internal combustion engine implicitly uses some kind
| of burning fuel; if on the other hand you want to use
| electricity as energy source, it needs a different kind of
| engine entirely. But that, as I understand from the post, is
| not the case here - heat pump as described here can operate
| on same principle and look broadly similar in its core parts,
| whether powered by electricity or something else.
| ars wrote:
| > There are also heat pump cycles that can be driven directly
| with heat.
|
| They are called
| https://en.wikipedia.org/wiki/Absorption_heat_pump
|
| But they are much less efficient that electrical ones, adding
| even a small amount of electricity to the cycle (even if the
| primary energy is heat) can dramatically improve efficiency.
| zozbot234 wrote:
| Strictly speaking you don't need a phase change in the fluid
| for a viable heat pump; pressure change is enough albeit with
| worse efficiency. Even something as simple as a Stirling engine
| with forced circulation of the fluid works as a heat pump.
| elil17 wrote:
| If you are referring to transcritical CO2 that is absolutely
| right. However you can't just use any pressure change in any
| gas, it would work but it would not be economically viable
| due to that inefficiency.
| rootusrootus wrote:
| > There are also heat pump cycles that can be driven directly
| with heat. Refrigerators based on that are relatively common
| here in Canada in areas without reliable grid electricity.
| Usually a propane or natural gas flame.
|
| Notably, the propane fridges used in RVs (which AFAIK usually
| use ammonia for the refrigerant) are extremely inefficient.
| They have the huge upside of requiring very little electrical
| power to operate, but would never be my choice if I wasn't
| tightly limited on electrical power.
| fasteddie31003 wrote:
| I had a similar idea when I was designing a heating system for a
| mountain house I was planning on building. I was planning on
| primarily heating with an oversized wood stove. The excess heat
| the wood stove would produce would be captured by a heat pump
| inside the house with its coils in a 500 gallon tank of water
| that was well insulated. When the house needed heat you could run
| the heat pump in reverse or make a system that removed the
| insulation around the tank of water letting the heat out. I had a
| spreadsheet with the heat calculations. I think the water at 150F
| degrees had around a megawatt of energy stored in it and that
| could have heated the house for a couple weeks. I never ended
| building that house, but would love to build a system like this
| in the future.
| zdragnar wrote:
| Outdoor wood boilers have been a thing for a long time. Back
| when I had mine, it kept the water at 180F.
|
| https://en.wikipedia.org/wiki/Outdoor_wood-fired_boiler
|
| If you have enough sufficiently dry wood, downdraft
| gasification models burn extremely cleanly (they're effectively
| rocket stoves), but those models require a fair bit of
| maintenance, _especially_ if your wood is slightly wet or
| green, because soot can quickly build up on the water envelope.
| PinguTS wrote:
| I have about 1050 US gallons (4000 l) of water storage in my
| house. The very effective wooden carburettor heating system is
| heating up the water storage. Then you use the water storage
| for next days until you have to re-fire.
|
| That is a standard package provided by many companies from
| Austria and Germany.
| macinjosh wrote:
| Half way through the article the author is touting how these can
| work in cold climates like Norway, then their example homeowner
| immediately states they have this but also they still have a
| furnace for when it actually is cold. Why do journalists try to
| pull crap like this? Contradictory information in the same
| paragraph!?
|
| If you have to have a backup it is _not_ a replacement and it
| will not get us off of carbon. Most people cannot afford a heat
| pump system much less a heat pump _and_ a furnace. Heat pumps
| seem great for moderate climates but it is not gonna happen up
| north where things actually get cold and stay cold for long
| periods of time.
|
| Anyone who actually has experienced this type of cold would run
| in the opposite direction of a heating technology that produces
| less warmth the colder it gets outside. Literally the opposite of
| what is needed for existence.
| motorogo wrote:
| If you read the article carefully, it notes that part of the
| problem in some colder climates is a lack of home insulation.
| Norwegian homes are well-insulated and therefore very suitable
| for heat pumps. The home owner with the furnace was US-based,
| by the way.
|
| The author is not "pulling crap" because they point out the
| real experience of Norwegian home owners while also describing
| the diversity of heat pump installations and outcomes.
|
| They're actually being very honest.
| rainsford wrote:
| A solution doesn't have to move us away from fossil fuels all
| by itself to be a useful piece of the puzzle. Even if heat
| pumps were only viable in places that don't regularly get super
| cold in the winter (which isn't true), that's a huge number of
| places covering a large portion of the population. A lot of the
| US, for example, gets hot enough in the summer that you want
| central air conditioning but also gets moderately cold in the
| winter. A heat pump system can cover you all year round with
| the same exact system. If you install a backup heat source,
| which can be electric by the way, that covers even more
| potential installation locations.
| post_break wrote:
| My dryer is a heat pump. The only issue is it takes a long time
| to dry my clothes, but the benefits are huge power use decrease,
| and so much more gentle on my clothes.
| Lisa_Novak wrote:
| [dead]
| H4ZB7 wrote:
| TIL heat pumps weren't invented in the last few years
| LatteLazy wrote:
| Everyone is looking for an easy answer to climate change / energy
| costs / energy independence etc. But there isn't one. Fusion
| remains decades away, Fission is very expensive and unpopular,
| Most renewables are intermittent etc. Heat pumps are one more
| tech with very limited potential (range of temperatures,
| efficiency over that range, power output limits, need for a heat
| source, size, cost etc).
| wpietri wrote:
| Wait, you are telling a bunch of technologists that no
| technology is perfect? Stop the presses! Which, dang it, are
| clearly also an imperfect technology if we have to stop them
| every time there's fresh news.
| thomasjb wrote:
| What's your perspective on sustainable biomass usage such as
| pollarding and coppicing, and bringing energy usage inline with
| that which can be fueled by them, in addition to small scale
| wind?
| Freestyler_3 wrote:
| I don't follow how heat pumps have limited potential. They have
| big potential.
|
| Its not a one size fits all solution, that's all.
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