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I live in a colder climate where heat pumps are not popular. After talking with a number of HVAC people about this I was surprised to learn that despite being

I live in a colder climate where heat pumps are not popular. After talking with a number of HVAC people about this I was surprised to learn that despite being very similar to an AC system in principle, in practice converting an AC system into a heat pump system doesn't make economic sense--you end up just ripping one out and installing the other. I don't fully understand why this is the case, but I hope that there's something that can be done to improve it. I'd love it if I could drive my AC unit as a heater for 95% of the winter, resorting to natural gas only during in the extreme cases.

deleted 3y ago
[deleted]
nightski 3y ago
The thing is (especially where I live) I'd still need a gas furnace. We regularly see -20F to -40F in the winter. While the 95% scenario sounds great, in practice still needing gas means we still need all the gas infrastructure. From my understanding natural gas burns pretty clean. The problem is leaks in infrastructure and drilling, which isn't going away because I buy a heat pump.
- GlickWick 3y ago
  They make heat pumps with backup gas systems now.
- elil17 3y ago
  Although natural gas is "clean" compared to, say, coal, the advantage of a heat pump is that it uses less total energy than natural gas. That means it would be more efficient to run a heat pump off a natural gas power plant than to burn natural gas to heat your home directly.
  - __MatrixMan__ 3y ago
    Where I live, you can bank solar credits. If you cash them out you get the "wholesale" energy price for them (much lower), but if you spend them on electricity then you've avoided paying full price for that electricity. So if your system produces more than you consume, you've got this free energy budget to spend--a budget that applies to heat pumps and not to gas furnaces.
  - Alupis 3y ago
    People's AC summertime electric bills regularly get into triple-digits - it's not uncommon to hear someone with a moderately sized home having a $200-400 electric bill in the summertime. However, even in the midst of winter, gas heating bills rarely climb above $100 monthly. What am I missing here? It seems a heatpump, while more efficient, will cost significantly more to operate. Natural Gas is cheap... and clean enough.
    - kibwen 3y ago
      It's actually difficult to say what the cost would be if everyone switched over. The reason is that natural gas is subsidized, both on the production side (at least in the US, which wants energy security) and on the consumption side (because it's politically unpopular to let people freeze to death). Of course, electricity prices are also affected by subsidies. Figuring out the true operating prices would require some research. However, it remains true that, in terms of greenhouse gas emissions, it is usually preferable to heat a home with a heat pump than by burning gas directly (there exists a temperature below which any given unit will become less efficient than burning gas, but unless you live in a place where this temperature is common then heat pumps will still come out on top (and the fact that residential gas lines are notoriously leaky and basically just venting nonstop into the atmosphere makes the calculation even more favorable)).
      - Alupis 3y ago
        It seems to me, there is no future where a heatpump can be the only source of in-home heating then. 1) Natural Gas is vastly cheaper in most/all of the US. 2) Homes still require an alternative heating source when temperatures drop to low levels (coincidentally when people need heating the most). So, even if a heatpump is technically more efficient in terms of emissions, the technology does not solve all of the problems it's attempting to replace. Additionally, Natural Gas is vastly more clean in terms of emissions than some other alternatives still used around the country. There's no way the average home is going to stomach 2-4x more heating expenses on average without some real tangible benefit (hand-wavy emissions numbers don't factor into the average homeowner's decision making). I must be missing something here...
- bklyn11201 3y ago
  You need a backup heat source, but it doesn't necessarily mean you need full infrastructure of gas lines, ducting, and gas furnace. You could have an electric backup connected to ducted heat pump (e.g., non-efficient, pure electric) or could use electric strip heating, electric portable heaters, wood stoves, etc.
  - nightski 3y ago
    We have electric baseboard. It would cost hundreds more per month to utilize something like that instead of gas when it is -30F. In fact if we just leave it on over night a single time we notice it on our bill.
- thehoff 3y ago
  Replaced our entire system (furnace, a/c) mid last year. Heat pump with backup oil for colder days. We cut the amount of gallons we used by over 50% compared to last year. Sure the oil infrastructure is needed to get it delivered (I wish we didn't need it) but I'm very happy that our heating (oil+electricity) bills are so much lower, even with the increased oil prices. We went with a mid-range system but now I kind of wish we sprung for the "Cadillac" version.
  - nightski 3y ago
    I suppose this would be true if gas is expensive where you live. It's really cheap here, our heating bill is like $80/mo in the coldest of months for a 3k sq ft house. A heat pump even with the efficiency gains would be on par with that (unless we jumped into solar, which I have considered).
elil17 3y ago
There's no reason you couldn't just switch a couple valves out in your AC and perhaps change the refrigerant to make it into a serviceable heat pump. However, you'd need to retrofit controls/electronics, which I don't think most HVAC technicians would know how to do. It's also not advisable to attempt to DIY something like this because it is very easy to accidentally vent the refrigerant, which is a very potent greenhouse gas.
- __MatrixMan__ 3y ago
  Right. It's a problem best confronted by the AC manufacturer. Except they have no incentive to do so (because if they don't, they get to sell an entirely separate heat pump down the line). Which means it's perhaps a problem for the regulator. There are tax breaks involved with installing "energy star" rated equipment. Perhaps we ought to start witholding the star from AC units that are not easy to convert to heat pumps (and from thermostats, etc, which are not ready to handle the conversion).
  - elil17 3y ago
    I think that would be an excellent regulatory solution. You should write to your representatives. Since heat pumps are getting a lot of regulatory attention, it might actually get considered.
- amluto 3y ago
  By the time you do that, you might as well also put in a variable speed compressor and a variable speed fan, at which point there’s not much left. (Seriously, where I live, you will likely pay $1k or slightly more to drain and refill the refrigerant. The hardware for an entire modern heat pump, indoor and outdoor components, is maybe $3-4k. Is it really worth it to drain an old existing unit, cut the pipes, add a reversing valve, retrofit in the controls, pressure test everything, deal with the fact that the outdoor unit (formerly the condenser coil) will start producing copious amounts of condensate that the manufacturer and installer did not anticipate, and refill the system?)
  - 3y ago
GlickWick 3y ago
I switched in New England when my freon system hit end of life. I wouldn’t recommend doing it beforehand, but as a replacement it’s been incredible. All the ductwork and infrastructure largely remained the same. Pulled out the furnace, evaporator coils, and compressor of course. It cools better than the old system, and the fact that it runs longer instead of in short bursts means it regulates humidity way better too. For heat we did go dual fuel, which means the backup heating element uses gas, since we already had the line. This works really well in a cold snap where temps drop well below freezing.
- ilamont 3y ago
  Fellow New Englander here. We had a 4 unit heat pump system installed a few years ago, replacing a bunch of window air conditioners. Not only is it a vast improvement over the window ACs in terms of ease of use, sound levels, comfort, and electricity use, it has become our default heat source in the winter as well, greatly reducing our natural gas bills.
deleted 3y ago
[deleted]
earlyriser 3y ago
I live some 5 hours north of Montreal, we have few days at -40C and wall radiators (not sure about the name) are needed, but for most of the winter days we use the heat pump to heat the house (-21C and up). Some members in my family work in AC/Refrigeration industry and all of them have thermo pumps, which make economic and ecologic sense. On the other side I don't know about AC/heat pump replacements as it's not common to have AC for the just a handful of days that could be very hot.
epistasis 3y ago
It's a $300 part that allows swapping the direction of heat flow. This tiny upfront cost is enough to block tons of good practice. Nate the House Whisperer is a guy who has been trying to build a new generation of HVAC practice, and though he says he's usually a libertarian, he advocates for adding a tax to AC-only units that would eliminate this price difference (or some similar practice, I forget the exact details...)
jillesvangurp 3y ago
This persistent myth just needs to go away. People use heat pumps all over Scandinavia, including in the arctic circle. They are extremely popular there. They were early adopters of this technology there decades ago. There are two popular varieties: - Ground source heat pumps. Those work pretty much anywhere; just dig below the perma frost and you are good to go on the northern tip of Canada, Alaska, Norway, or wherever. Works great, ground temperatures tend to be very stable and it actually goes up the deeper you dig. - Air source heat pumps. The expensive ones still work okish at extreme temperatures like -25-ish degrees C. Which is a reason these are actually more popular than ground sources even in places (e.g. most of Scandinavia) that reliably get such temperatures each winter.
- __MatrixMan__ 3y ago
  I've been on zoom calls with two separate co-workers who are all bundled up because their heat pump can't handle the weather. It doesn't mean that the technology is inadequate in principle--probably their systems have some problem that competent HVAC installers know how to avoid. But its an unfortunate fact that there are places in the US where installers that recommend heat pumps can't be found for 100 miles. It doesn't really matter if I'm technically correct about the merits of the tech in principle--if I can't find somebody to fix my system and my pipes start exploding, I've still made the wrong decision. Also, heavy snows cause power outages in places where tree limbs fall on overhead lines. If gas outages happen... well I've never experienced one. Sure, if I lived in Norway I'd have a government that cares about updated infrastructure and I wouldn't have these problems, but since I don't, I do. Given my local constraints, a dual-fuel system sounds pretty great.
  - jillesvangurp 3y ago
    Gas outages happened at a large scale in Texas when they were struggling with a bit of cold weather. When they needed it the most, it failed them. Coal plants also struggled. Both had challenges with supply of fuel and cooling water being disrupted. That kind of systemic infrastructure failures is on the rise in the US. There are all sorts of reasons why governance just isn't great in the US. But the reality indeed is that things are unlikely to improve on that front. Which are all good reasons why the market for domestic solar, batteries, and heat pumps is so hot right now. The US is no exception to this.
amluto 3y ago
Converting an A/C to a heat pump is a bit like upgrading an old Lenovo laptop to a modern CPU. It’s surely doable, and the parts are unlikely to be terribly expensive, but as a practical matter it’s pretty specialized and no one does it. What you do is wait for the A/C to hit end of life (or end of efficient life if new systems are enough more efficient) and replace it outright. (I once got a quote, in an expensive market, to add an A/C to an existing furnace and, separately, to remove the furnace and add a three-head multi-split heat pump. The two quotes were almost the same price. The equipment is not especially expensive.)
Tor3 3y ago
Colder climate is exactly where you want to use heat pumps. The numbers for Norway in 2022 (https://www.novap.no/om-varmepumper https://www.novap.no/om-varmepumper) is 58% of Norwegian homes (houses) have a heat pump installed, 34% in service industries, 8% in other industries. For homes air-to-air dominates (more than 90%). And since then this has just increased even more (and older heat pumps are being replaced with newer and better ones as well). As an aside, many have commented on the claim that heat pumps make more sense with a well insulated building, arguing that it should be the other way around. The reason that you do want a well insulated building is simply that air-to-air heat pumps are limited to typically less than around 8kW heating capacity, and with a well insulated house you can heat a large area with that, with bad insulation you can't, and you would need a much more expensive type - typically not those sold to home owners (or buy several pumps, exploding the costs). In addition to that, a heat pump is more efficient when it doesn't have to run at maximum capacity. The heat pumps sold in the Nordic countries are typically around $3000 including installation. And they're highly efficient.

deleted 3y ago

[deleted]

nightski 3y ago

The thing is (especially where I live) I'd still need a gas furnace. We regularly see -20F to -40F in the winter. While the 95% scenario sounds great, in practice still needing gas means we still need all the gas infrastructure. From my understanding natural gas burns pretty clean. The problem is leaks in infrastructure and drilling, which isn't going away because I buy a heat pump.

GlickWick 3y ago
They make heat pumps with backup gas systems now.
elil17 3y ago
Although natural gas is "clean" compared to, say, coal, the advantage of a heat pump is that it uses less total energy than natural gas. That means it would be more efficient to run a heat pump off a natural gas power plant than to burn natural gas to heat your home directly.
- __MatrixMan__ 3y ago
  Where I live, you can bank solar credits. If you cash them out you get the "wholesale" energy price for them (much lower), but if you spend them on electricity then you've avoided paying full price for that electricity. So if your system produces more than you consume, you've got this free energy budget to spend--a budget that applies to heat pumps and not to gas furnaces.
- Alupis 3y ago
  People's AC summertime electric bills regularly get into triple-digits - it's not uncommon to hear someone with a moderately sized home having a $200-400 electric bill in the summertime. However, even in the midst of winter, gas heating bills rarely climb above $100 monthly. What am I missing here? It seems a heatpump, while more efficient, will cost significantly more to operate. Natural Gas is cheap... and clean enough.
  - kibwen 3y ago
    It's actually difficult to say what the cost would be if everyone switched over. The reason is that natural gas is subsidized, both on the production side (at least in the US, which wants energy security) and on the consumption side (because it's politically unpopular to let people freeze to death). Of course, electricity prices are also affected by subsidies. Figuring out the true operating prices would require some research. However, it remains true that, in terms of greenhouse gas emissions, it is usually preferable to heat a home with a heat pump than by burning gas directly (there exists a temperature below which any given unit will become less efficient than burning gas, but unless you live in a place where this temperature is common then heat pumps will still come out on top (and the fact that residential gas lines are notoriously leaky and basically just venting nonstop into the atmosphere makes the calculation even more favorable)).
    - Alupis 3y ago
      It seems to me, there is no future where a heatpump can be the only source of in-home heating then. 1) Natural Gas is vastly cheaper in most/all of the US. 2) Homes still require an alternative heating source when temperatures drop to low levels (coincidentally when people need heating the most). So, even if a heatpump is technically more efficient in terms of emissions, the technology does not solve all of the problems it's attempting to replace. Additionally, Natural Gas is vastly more clean in terms of emissions than some other alternatives still used around the country. There's no way the average home is going to stomach 2-4x more heating expenses on average without some real tangible benefit (hand-wavy emissions numbers don't factor into the average homeowner's decision making). I must be missing something here...
bklyn11201 3y ago
You need a backup heat source, but it doesn't necessarily mean you need full infrastructure of gas lines, ducting, and gas furnace. You could have an electric backup connected to ducted heat pump (e.g., non-efficient, pure electric) or could use electric strip heating, electric portable heaters, wood stoves, etc.
- nightski 3y ago
  We have electric baseboard. It would cost hundreds more per month to utilize something like that instead of gas when it is -30F. In fact if we just leave it on over night a single time we notice it on our bill.
thehoff 3y ago
Replaced our entire system (furnace, a/c) mid last year. Heat pump with backup oil for colder days. We cut the amount of gallons we used by over 50% compared to last year. Sure the oil infrastructure is needed to get it delivered (I wish we didn't need it) but I'm very happy that our heating (oil+electricity) bills are so much lower, even with the increased oil prices. We went with a mid-range system but now I kind of wish we sprung for the "Cadillac" version.
- nightski 3y ago
  I suppose this would be true if gas is expensive where you live. It's really cheap here, our heating bill is like $80/mo in the coldest of months for a 3k sq ft house. A heat pump even with the efficiency gains would be on par with that (unless we jumped into solar, which I have considered).

elil17 3y ago

There's no reason you couldn't just switch a couple valves out in your AC and perhaps change the refrigerant to make it into a serviceable heat pump. However, you'd need to retrofit controls/electronics, which I don't think most HVAC technicians would know how to do. It's also not advisable to attempt to DIY something like this because it is very easy to accidentally vent the refrigerant, which is a very potent greenhouse gas.

__MatrixMan__ 3y ago
Right. It's a problem best confronted by the AC manufacturer. Except they have no incentive to do so (because if they don't, they get to sell an entirely separate heat pump down the line). Which means it's perhaps a problem for the regulator. There are tax breaks involved with installing "energy star" rated equipment. Perhaps we ought to start witholding the star from AC units that are not easy to convert to heat pumps (and from thermostats, etc, which are not ready to handle the conversion).
- elil17 3y ago
  I think that would be an excellent regulatory solution. You should write to your representatives. Since heat pumps are getting a lot of regulatory attention, it might actually get considered.
amluto 3y ago
By the time you do that, you might as well also put in a variable speed compressor and a variable speed fan, at which point there’s not much left. (Seriously, where I live, you will likely pay $1k or slightly more to drain and refill the refrigerant. The hardware for an entire modern heat pump, indoor and outdoor components, is maybe $3-4k. Is it really worth it to drain an old existing unit, cut the pipes, add a reversing valve, retrofit in the controls, pressure test everything, deal with the fact that the outdoor unit (formerly the condenser coil) will start producing copious amounts of condensate that the manufacturer and installer did not anticipate, and refill the system?)
- 3y ago

GlickWick 3y ago

I switched in New England when my freon system hit end of life. I wouldn’t recommend doing it beforehand, but as a replacement it’s been incredible. All the ductwork and infrastructure largely remained the same. Pulled out the furnace, evaporator coils, and compressor of course. It cools better than the old system, and the fact that it runs longer instead of in short bursts means it regulates humidity way better too. For heat we did go dual fuel, which means the backup heating element uses gas, since we already had the line. This works really well in a cold snap where temps drop well below freezing.

ilamont 3y ago
Fellow New Englander here. We had a 4 unit heat pump system installed a few years ago, replacing a bunch of window air conditioners. Not only is it a vast improvement over the window ACs in terms of ease of use, sound levels, comfort, and electricity use, it has become our default heat source in the winter as well, greatly reducing our natural gas bills.

deleted 3y ago

[deleted]

earlyriser 3y ago

I live some 5 hours north of Montreal, we have few days at -40C and wall radiators (not sure about the name) are needed, but for most of the winter days we use the heat pump to heat the house (-21C and up). Some members in my family work in AC/Refrigeration industry and all of them have thermo pumps, which make economic and ecologic sense. On the other side I don't know about AC/heat pump replacements as it's not common to have AC for the just a handful of days that could be very hot.

epistasis 3y ago

It's a $300 part that allows swapping the direction of heat flow. This tiny upfront cost is enough to block tons of good practice. Nate the House Whisperer is a guy who has been trying to build a new generation of HVAC practice, and though he says he's usually a libertarian, he advocates for adding a tax to AC-only units that would eliminate this price difference (or some similar practice, I forget the exact details...)

jillesvangurp 3y ago

This persistent myth just needs to go away. People use heat pumps all over Scandinavia, including in the arctic circle. They are extremely popular there. They were early adopters of this technology there decades ago. There are two popular varieties: - Ground source heat pumps. Those work pretty much anywhere; just dig below the perma frost and you are good to go on the northern tip of Canada, Alaska, Norway, or wherever. Works great, ground temperatures tend to be very stable and it actually goes up the deeper you dig. - Air source heat pumps. The expensive ones still work okish at extreme temperatures like -25-ish degrees C. Which is a reason these are actually more popular than ground sources even in places (e.g. most of Scandinavia) that reliably get such temperatures each winter.

__MatrixMan__ 3y ago
I've been on zoom calls with two separate co-workers who are all bundled up because their heat pump can't handle the weather. It doesn't mean that the technology is inadequate in principle--probably their systems have some problem that competent HVAC installers know how to avoid. But its an unfortunate fact that there are places in the US where installers that recommend heat pumps can't be found for 100 miles. It doesn't really matter if I'm technically correct about the merits of the tech in principle--if I can't find somebody to fix my system and my pipes start exploding, I've still made the wrong decision. Also, heavy snows cause power outages in places where tree limbs fall on overhead lines. If gas outages happen... well I've never experienced one. Sure, if I lived in Norway I'd have a government that cares about updated infrastructure and I wouldn't have these problems, but since I don't, I do. Given my local constraints, a dual-fuel system sounds pretty great.
- jillesvangurp 3y ago
  Gas outages happened at a large scale in Texas when they were struggling with a bit of cold weather. When they needed it the most, it failed them. Coal plants also struggled. Both had challenges with supply of fuel and cooling water being disrupted. That kind of systemic infrastructure failures is on the rise in the US. There are all sorts of reasons why governance just isn't great in the US. But the reality indeed is that things are unlikely to improve on that front. Which are all good reasons why the market for domestic solar, batteries, and heat pumps is so hot right now. The US is no exception to this.

amluto 3y ago

Converting an A/C to a heat pump is a bit like upgrading an old Lenovo laptop to a modern CPU. It’s surely doable, and the parts are unlikely to be terribly expensive, but as a practical matter it’s pretty specialized and no one does it. What you do is wait for the A/C to hit end of life (or end of efficient life if new systems are enough more efficient) and replace it outright. (I once got a quote, in an expensive market, to add an A/C to an existing furnace and, separately, to remove the furnace and add a three-head multi-split heat pump. The two quotes were almost the same price. The equipment is not especially expensive.)

Tor3 3y ago

Colder climate is exactly where you want to use heat pumps. The numbers for Norway in 2022 (https://www.novap.no/om-varmepumper https://www.novap.no/om-varmepumper) is 58% of Norwegian homes (houses) have a heat pump installed, 34% in service industries, 8% in other industries. For homes air-to-air dominates (more than 90%). And since then this has just increased even more (and older heat pumps are being replaced with newer and better ones as well). As an aside, many have commented on the claim that heat pumps make more sense with a well insulated building, arguing that it should be the other way around. The reason that you do want a well insulated building is simply that air-to-air heat pumps are limited to typically less than around 8kW heating capacity, and with a well insulated house you can heat a large area with that, with bad insulation you can't, and you would need a much more expensive type - typically not those sold to home owners (or buy several pumps, exploding the costs). In addition to that, a heat pump is more efficient when it doesn't have to run at maximum capacity. The heat pumps sold in the Nordic countries are typically around $3000 including installation. And they're highly efficient.