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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 free

• cinntaile 4y ago
  That sounds like it would be very expensive and error prone.
• retrac 4y ago
  > 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 4y ago
    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.
    • tonyarkles 4y ago
      And incandescent light bulbs!
      • elil17 4y ago
        No, because the light can escape through windows.
        • maxk42 4y ago
          So can heat. That's not the appliance's fault.
          • elil17 4y ago
            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.
            • Dylan16807 4y ago
              Thermal infrared doesn't go through glass. You only lose a negligible amount of visible light. It's still 100% efficient as an integer percent.
              • elil17 4y ago
                I assume by “thermal infrared” you mean the IR produced by approximately room temperature objects. Incandescent bulbs produce much higher energy infrared because the filament reaches about 2000 Celsius. Those higher energy waves can go through glass.
                • Dylan16807 4y ago
                  Right, that's true, I was thinking about it wrong. Still, not much is going to hit a window on average. So maybe 90% efficient.
    • ComputerGuru 4y ago
      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!
    • tshaddox 4y ago
      “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).
    • elil17 4y ago
      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 4y ago
        Gas boilers produce NO2, and other nasties - they do affect air quality in your house
        • kwhitefoot 4y ago
          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 4y ago
            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 4y ago
              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.
              • abakker 4y ago
                My meter here in boulder, CO reads effectively 0 VOC outdoors all year round.
    • kibwen 4y ago
      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.
    • vanviegen 4y ago
      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.
      • tutorialmanager 4y ago
        Get buckets of water from your pool (or lake or well) and put them in the fridge till they cool down. Then dump the water outside and get a new bucketful). To save effort you could run 2 hoses with a small pump. You are now heating your house with a ground source heat pump. I really enjoyed reading The Homemade Heatpump Manifesto on Ecorenovator. https://ecorenovator.org/forum/showthread.php?t=484 https://ecorenovator.org/forum/showthread.php?t=484
    • briHass 4y ago
      In the summer, my heat pump water heater in the basement is essentially 'free' to run, since most of the heat it captures is by condensing water in the air i.e. dehumidifying my basement. I still need a dehumidifier, but it doesn't have to run as hard.
  • Scoundreller 4y ago
    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.
    • mixmastamyk 4y ago
      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.
      • Scoundreller 4y ago
        Just have tubs of water. Dump them once they’re ice. Yes, more efficient than a resistance heater. Possibly more cost efficient than gas. Wastes a lot of water (if you don’t have a well). A fridge is just a heat pump.
    • bobthepanda 4y ago
      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)
  • stuaxo 4y ago
    The back of my fridge is in a really confined space, like many fridges - that heat would be better taken somewhere else.
• IMTDb 4y ago
  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 4y ago
    > 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?
• jillesvangurp 4y ago
  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 4y ago
    Simple- just keep the fridge doors open during the summer
    • naijaboiler 4y ago
      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.
• rpearl 4y ago
  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 4y ago
    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 4y ago
      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.
    • briHass 4y ago
      This is one of the bigger myths used to sell tankless. Modern water heater tanks are well insulated; losses are usually quoted as less than 10%. From a cost perspective, the slight efficiency increase of tankless never pays back over the cost of the unit, and unfortunately, usually the more frequent repairs. The big benefit is the 'unlimited' hot water.
• mschuster91 4y ago
  > 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 https://en.wikipedia.org/wiki/District_cooling
• AlanSE 4y ago
  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.
  • ballenf 4y ago
    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.
    • soco 4y ago
      Is the AC dehumidifier an extra feature/task, so actively followed, or is it doing dehumidification just as a byproduct happening while cooling?
      • rstupek 4y ago
        It's a byproduct of the process of cooling the air
      • 4y ago
• rr808 4y ago
  Pool heater too. In our building we have massive AC units and a separate heat pump to warm the pool.
• azdle 4y ago
  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 4y ago
    Here's a research paper detailing a design for your idea: https://www.sciencedirect.com/science/article/abs/pii/S0360544221015516 https://www.sciencedirect.com/science/article/abs/pii/S03605... It was never pursued further for reasons I discussed in another comment on this thread.
• homero 4y ago
  Your fridge is already doing it. It's heating your house
• phkahler 4y ago
  The fridge is heating your home, so that reduces the burden on whatever is heating your home. The coil on the back gets hot.
  • blacksmith_tb 4y ago
    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.
  • teruakohatu 4y ago
    > 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.
    • tiagod 4y ago
      The heat is coming from the inside of the fridge and from the power used. It's net positive heat.
    • deleted 4y ago
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• elil17 4y ago
  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 4y ago
    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 4y ago
  I think you are going to like section IV of: https://bayes.wustl.edu/etj/articles/AJP00180.pdf https://bayes.wustl.edu/etj/articles/AJP00180.pdf
• 1ris 4y ago
  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.
• ChainOfFools 4y ago
  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.
  • redeeman 4y ago
    > nd 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. that makes no sense. effective insulation is no problem at all. In large parts of europe they even have centralized water heating and run insulated hotwater pipes to houses across kilometers without huge losses, hell, for this kind of setup it would even be possible to just run refridgerant, which typically specs at ~15m for minisplits as maximum(with very minor losses) distance
• jopsen 4y ago
  > 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 Installing ducts, etc. might take more energy than is consumed over the product life-cycle. It would add other limitations, such as only being able to put fridges next to exterior wall. Or most likely it'll add additional installation cost. Money perhaps better spent insulating your house better. You'd have fewer compatible vendors to choose from. Less competition. Flexibility is probably way more important than micro optimizations.
• mabbo 4y ago
  Your fridge and freezer are warming your home. They move the heat from inside the fridge to outside. That heats up your home. This reduces your need to heat your home, temporarily. Generally, every device in your home that uses electricity is creating roughly the same amount of heat as an electric heater would have using the same amount of electricity. Even fridges and freezers, so long as nothing is being vented outside.