Are Air-to-Water Heat Pumps Finally Ready for Extreme Cold Climates?

arcticheatpumps7 · 9:15AM

I've been working with hydronic heating systems for a while and have noticed a growing interest in air-to-water heat pumps, especially in regions that experience harsh winters.

Traditionally, many homeowners and contractors have been skeptical about heat pumps because performance tends to drop significantly as outdoor temperatures fall. However, newer cold-climate systems claim to operate efficiently even in temperatures as low as -31°F (-35°C).

What interests me most is the ability of these systems to integrate with:

Radiant floor heating
Fan coil systems
Domestic hot water production
Existing hydronic heating setups

Some manufacturers are also offering monoblock designs, which simplify installation and reduce refrigerant work on-site.

For those who have installed or serviced cold-climate air-to-water heat pumps:

How have they performed during extended cold snaps?
Are homeowners seeing meaningful energy savings compared to propane, oil, or electric resistance heating?
What challenges have you encountered with retrofits?
Do you still recommend backup heat sources in very cold regions?

I'd be interested to hear real-world experiences from contractors, designers, and homeowners.

pecmsg · 10:27AM

Any facts to back this up?

hot_rod · 1:07PM

You need to do the homework when considering on a A2whp

The required operating temperature at design condition is one critical number.

Staying below 120 is a good goal. So large surface area emitters like radiant panels work best.

Data is available from manufacturers and independent testing on efficiency drop as outdoor temperatures drop. No guessing required. Same with performance at higher operating temperatures

This info, in graph form was in my installation manual. Realistic numbers not sales hype.

Operating cost comparison is directly related to the various fuel cost at the insty locat. That data is also available going back 30 years or more. The question is fuel costs going forward?

I would also pull the data to see how many days a location is at or below design when considering a backup system.

Some do, some don’t consider the installed cost of a HP. ROI is another hard to pin down number. System longevity is a question Refrigerators have a 15-20 year lifespan, as far as the compressor snd components

Lots if electronics under the hood A piwer conditioner is a goid option.

Qualified installer and service people needs to be considered. It takes multiple skills to troubleshoot a HP

I’m going on 3 years with a Viessmann system running 120 SWT to radiant slabs. Just started running chilled water to the slab for cooling. So far I am pleased with the operation and operation cost

Electric rates vary between 11– 13 cents, and I have enough PV to run the system on sunny days

So for me, all the boxes checked.

Replacing or a new installation on a system needing 140 or more, especially in cold climates. This may end up with some heart break.

DCContrarian · 2:54PM

"Traditionally, many homeowners and contractors have been skeptical about heat pumps because performance tends to drop significantly as outdoor temperatures fall. However, newer cold-climate systems claim to operate efficiently even in temperatures as low as -31°F (-35°C)."

It's not just that efficiency drops, it's that output drops. Unlike combustion appliances where a BTU is a BTU, heat pumps produce far less than their nameplate capacity in cold weather.

A big advantage of air-to-water is that buffer tanks make oversizing less of an issue. So you can size for actual loads on heating design days without being oversized in moderate weather.

hot_rod · 3:31PM

An example for the Viessmann

pecmsg · 4:31PM

One major issue with all these Low Temp Heat Pumps Weather Air to Air, Air to Water, or Water to Water is finding someone that knows how to work on them and getting ahold of tech support after hours, holidays and weekends! A lot of computers are in there. I'd still want a backup plan.

hot_rod · 7:05PM

https://forum.heatinghelp.com/discussion/comment/1898227#Comment_1898227

It really depends on the brand.

Viessmann tech support answers the phone. If they are busy they call or txt back within an hour. I've spoken to several different tech support, mostly in Waterloo, Canada a 1/2 dozen times as I programed the unit.

In some cases the local rep for the area is helpful.

Maybe not so for some of the imports from China purchased online.

pecmsg · 7:17PM

I agree Viessmann may be an exception to that rule.

Mitsubishi, Daykin, Fujitsu all normal business hours, and were not even going to discuss parts availability.

mattmia2 · 7:25PM

Longevity is a really important factor in the math here too. There is no reason they shouldn't last 40 years with proper engineering but I doubt that most actually will, maybe the Viessman if they are actually building them in Germany or at least Africa.

pecmsg · 7:34PM

I can't speak for Viessman, but "Most" heat pumps are 7 1/2 -10 years before parts are obsolete.

Are Air-to-Water Heat Pumps Finally Ready for Extreme Cold Climates?

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