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Heat Pumps Take on Cold Climates

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41–50 of 83 posts

Re: Heat Pumps Take on Cold Climates

#41
post #3

Is there a way to get your house (currently with hydronic gas heat) retrofitted for heat pumps that doesn’t result in either a ton of demo or ugly lines all over the exterior? I tried to switch over last year only to find the savings were not that great in my climate, and that it would have an unacceptable aesthetic cost.

Yes, a "heat pump combi boiler" will replace your existing hot water heater and boiler for heating leaving most of the visible infrastructure intact.

Re: Heat Pumps Take on Cold Climates

#42

Earlier quoted context omitted.

I guess this depends on where you locate the heat pump. On mine, the insulated pipe and mains connection are within two feet of the building.

Is yours air-to-air?

It is -- it looks just like an air conditioner plopped on a pad. There's two lines connected to it and leading into the house; one is an insulated copper pipe, and the other is the mains power connected to an electrical disconnect box.

Re: Heat Pumps Take on Cold Climates

#43
post #11

As someone who switched to a heat pump recently, you should know "your mileage may vary." Don't confuse physical efficiency for cost efficiency. In many places, natural gas is still more cost efficient, even if it isn't as efficient in terms of physics.

For how long is gas likely to be cheaper? It’s generally more scarce right? Does anyone have predictions on US price over the next few decades?

Re: Heat Pumps Take on Cold Climates

#44
post #11

As someone who switched to a heat pump recently, you should know "your mileage may vary." Don't confuse physical efficiency for cost efficiency. In many places, natural gas is still more cost efficient, even if it isn't as efficient in terms of physics.

Natural gas is dirt cheap in most of the U.S., so it does make it hard for heat pumps to compete, especially if electricity is expensive. Just checked my most recent gas bill and I only paid $1.09/therm (plus 7% sales tax and $10 fixed fee). OTOH if you’re heating with propane or fuel oil, heat pumps are probably a good alternative.

Thats kind of high. I only pay $0.78 a therm here in Wisconsin. 1 therm is around 30kwh so im paying like 2.5c a kwh vs 17c for electricity. So unless I can get a CoP of 700% from a air source heatpump im literally lighting money on fire. That really is the main issue, as much as I care about emissions I don't care enough to spend money on a heat pump to then spend more money on utilities. And the calculus gets worse and worse when your poorer.

Re: Heat Pumps Take on Cold Climates

#45

Earlier quoted context omitted.

Is yours air-to-air?

It is -- it looks just like an air conditioner plopped on a pad. There's two lines connected to it and leading into the house; one is an insulated copper pipe, and the other is the mains power connected to an electrical disconnect box.

Did they retrofit the linesets through the walls to the interior units?

Or do you have existing ductwork (which a house with hydronic gas heat probably does not have, or else they'd probably not be asking the question)?

Re: Heat Pumps Take on Cold Climates

#47
post #11

As someone who switched to a heat pump recently, you should know "your mileage may vary." Don't confuse physical efficiency for cost efficiency. In many places, natural gas is still more cost efficient, even if it isn't as efficient in terms of physics.

Natural gas is dirt cheap in most of the U.S., so it does make it hard for heat pumps to compete, especially if electricity is expensive. Just checked my most recent gas bill and I only paid $1.09/therm (plus 7% sales tax and $10 fixed fee). OTOH if you’re heating with propane or fuel oil, heat pumps are probably a good alternative.

Last year I had to replace my HVAC. I was set on getting a heat pump, being a huge fan of efficiency. I was averaging a $1.05/therm delivered for gas, and about 17.5 cents/kwh for electricity delivered. A therm is about 29 kwh, so I pay the equivalent of $5.07/therm in electricity.

The best whole house air-source heat pumps had a SEER2 of 18.5, or a COP of just under 5.0. I need a COP of over 5 to just break even in terms of cost efficiency. So a heat pump would actually cost me more on an ongoing basis. And the price for a heat pump installation was $10k more than a furnace/AC.

I just couldn't do it. To pay more up front and then ongoing was just too much. If you showed me even a super long range projection of saving money, I would have been down for it, but it just was not there.

If I can get solar on my house it may make sense, I will cross that bridge in a few years as my roof is almost end of life, but that has its own headaches as I have limited space (brownstone, flat roof), and am in a historic district.

Next go around, as heat pump tech improves and hopefully gets cheaper, it will probably make sense, but for me right now, it just didn't work.

Re: Heat Pumps Take on Cold Climates

#48
post #11

As someone who switched to a heat pump recently, you should know "your mileage may vary." Don't confuse physical efficiency for cost efficiency. In many places, natural gas is still more cost efficient, even if it isn't as efficient in terms of physics.

For how long is gas likely to be cheaper? It’s generally more scarce right? Does anyone have predictions on US price over the next few decades?

As gas use declines, prices are likely to stay low. So probably a long time.

Re: Heat Pumps Take on Cold Climates

#49
post #2

> But heat pump manufacturers say they now have the technology to heat homes just as efficiently in bitter cold as they do in milder winter temperatures. This claim defies thermodynamics (and I expect better from IEEE). Heat pumps are bound to be less efficient as the spread between inside and outside temperature grows. (They might be just as effective or they might be just as efficient as current heat pump tech , bu…

In Kelvin the percentage difference looks a lot smaller than -20°C to +10°C, more towards a rounding error for an ideal heat pump.

So if they can operate at the same percentage efficiency away from ideal, the extra difference from the actual source/sink temperature could be very minimal right?

Re: Heat Pumps Take on Cold Climates

#50

Earlier quoted context omitted.

It is -- it looks just like an air conditioner plopped on a pad. There's two lines connected to it and leading into the house; one is an insulated copper pipe, and the other is the mains power connected to an electrical disconnect box.

Did they retrofit the linesets through the walls to the interior units? Or do you have existing ductwork (which a house with hydronic gas heat probably does not have, or else they'd probably not be asking the question)?

Yes, there is existing ductwork in the house.

I understand the situation -- I had searched to see if hydronic gas heating used ducts, and it can but it seems that this is not common.

Their issue is not an issue of heat pumps themselves, but rather the lack of an air handler.

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