Air to Water Heat Pump - Ever installed or used one? Need advice and recommendations

Prevch

I am in the process of replacing a propane boiler with an electric solution. In one of my other threads, someone brought up the idea of an electric air to water heat pump system. As I have been doing research online, it looks like there are some mixed reviews in colder climates. I live in Northern, WI, so it can get pretty cold here as you might expect.

Does anyone have any experience installing or using an air to water heat pump in a cold climate? What was your experience like? Do you happen to have any recommendations on brands?

Thank you everyone for your help and insights.

jesmed1

The big question is, how hot do you need your radiator water? If you have large radiating surfaces, ie radiant floor hydronic loops, then you have a lot of radiation surface area and can keep your water temps relatively low. This is favorable for a heat pump. OTOH, if you have a relatively small radiation surface area, eg old cast iron radiators designed for higher water temps, that's bad, because heat pumps have to work much harder to get higher water temps.

I live in a 4-unit condo building with old cast iron rads heated with oil boilers. I looked into air-to-water heat pumps, but the problem was that we need 130-140 degree water to get sufficient heat out of our radiators. And a heat pump that could do that was going to be very expensive.

Hot_water_fan

Here's a great resource: https://www.caleffi.com/sites/default/files/file/idronics_27_na.pdf

Heat pumps will work in Wisconsin, you'll probably use some backup for the coldest days.

EBEBRATT-Ed

Once the outside air drops below 32 the outside condenser will start to frost. That is physics and has nothing to do with whatever brand unit is installed or how well or how poorly it is installed. The unit will have to go into defrost mode because of this. Also since there is less heat available in the outside air the efficiency drops and the heat avail to the space drops.

None of the above means a HP is a poor choice they are just facts to consider. you have to consider everything including what will provide heat in really cold temperatures. Electric back up or some other source.

WMno57

Hot_water_fan said:

Heat pumps will work in Wisconsin, you'll probably use some backup for the coldest days.

Hot_water_fan

@WMno57 I’ve lived in Wisconsin, I know it’s cold. Hence the backup for the coldest days

WMno57

Hot_water_fan said:

@WMno57 I’ve lived in Wisconsin, I know it’s cold. Hence the backup for the coldest days

Great, so tell us, what do you think the ATW heat pump expertise in rural northern WI is? In another post the OP was having problems having someone come out to fix a gas line.
https://forum.heatinghelp.com/discussion/191270/my-utica-mac-205-boiler-sounds-like-the-horn-of-gondor#latest
@prevch in one of your posts you mention you have AC and I assume ductwork. Is a propane forced air furnace an option for you? Your not going to find much hydronics expertise in the great white north. Even less ATA heat pump experience. Probably zero ATW heat pump experience.
You said the Utica was installed 2018. Seems a shame to give up on that.

Hot_water_fan

@WMno57 I’m not trying to argue, I am simply answering a question. 

Prevch

jesmed1 said:

The big question is, how hot do you need your radiator water? If you have large radiating surfaces, ie radiant floor hydronic loops, then you have a lot of radiation surface area and can keep your water temps relatively low. This is favorable for a heat pump. OTOH, if you have a relatively small radiation surface area, eg old cast iron radiators designed for higher water temps, that's bad, because heat pumps have to work much harder to get higher water temps.

I live in a 4-unit condo building with old cast iron rads heated with oil boilers. I looked into air-to-water heat pumps, but the problem was that we need 130-140 degree water to get sufficient heat out of our radiators. And a heat pump that could do that was going to be very expensive.

Thanks for this info. I have in-floor radiant, so hoping that it would be a good fit.

Prevch

Hot_water_fan said:

Here's a great resource: https://www.caleffi.com/sites/default/files/file/idronics_27_na.pdf

Heat pumps will work in Wisconsin, you'll probably use some backup for the coldest days.

Thank you very much for that resource.

Prevch

EBEBRATT-Ed said:

Once the outside air drops below 32 the outside condenser will start to frost. That is physics and has nothing to do with whatever brand unit is installed or how well or how poorly it is installed. The unit will have to go into defrost mode because of this. Also since there is less heat available in the outside air the efficiency drops and the heat avail to the space drops.

None of the above means a HP is a poor choice they are just facts to consider. you have to consider everything including what will provide heat in really cold temperatures. Electric back up or some other source.

Thank you for that info. Yes, I do have backup electric heat via forced air right now, but want to take advantage of the hydronic in-floor loops we have throughout the home.

WMno57

Two types of ATW heat pumps, monobloc and split system.

Monobloc

• No refrigerant to run through lineset into house
  
• Comes pre charged with refrigerant
  
• In theory easier to DIY
  
• Requires glycol
  

Split System

• Refrigerant runs between evaporator outside and condenser inside (like traditional AC)
  
• Harder to DIY, need gauges, refrigerant, more knowledge. EPA says you need license.
  
• Should NOT require glycol if used for heating only (But Spacepak might require it anyway, see below)
  
• Requires glycol if used for cooling
  

https://forum.heatinghelp.com/discussion/193273/spacepak-split-inverter-heat-pump-sis-060a-glycol-head-loss
Do you have Glycol in your system now? Glycol opens a whole new can of worms.

Prevch

WMno57 said:

Hot_water_fan said:

Heat pumps will work in Wisconsin, you'll probably use some backup for the coldest days.

I don't live that far from there actuall

WMno57 said:

Hot_water_fan said:

@WMno57 I’ve lived in Wisconsin, I know it’s cold. Hence the backup for the coldest days

Great, so tell us, what do you think the ATW heat pump expertise in rural northern WI is? In another post the OP was having problems having someone come out to fix a gas line.
https://forum.heatinghelp.com/discussion/191270/my-utica-mac-205-boiler-sounds-like-the-horn-of-gondor#latest
@prevch in one of your posts you mention you have AC and I assume ductwork. Is a propane forced air furnace an option for you? Your not going to find much hydronics expertise in the great white north. Even less ATA heat pump experience. Probably zero ATW heat pump experience.
You said the Utica was installed 2018. Seems a shame to give up on that.

Thanks for that info. So as you saw in my previous post, I had tons of problems with that boiler. We also ended up having multiple gas leaks, one of which made my family sick. So between the constant break down issues, having no one able or willing to fix it and the gas leak incidents, I ripped it off the wall and it's going to be scrap metal now.

You are right though, I am guessing no one will be able to help me with the heat pump either, so I am going to have to do it myself. I will figure it out, but it is going to be a learning process. That's one of the reasons I appreciate this forum so much.

When I installed the ductwork and AC, I also put in a backup electric coil, so I have electric forced air heat right now that works fine until it gets maybe -5 or so and then struggles to keep up. That being said, I prefer the comfort of the hydronic loops. When the gas boiler actually worked, which was rare, I loved it with the in floor heat. I might not be able to get a perfect direct replacement for gas, but I will do my best with the resources I have. For super cold days, we also have a couple of wood burning stoves that can keep our whole house toasty.

Prevch

WMno57 said:

Two types of ATW heat pumps, monobloc and split system.

Monobloc

• No refrigerant to run through lineset into house
  
• Comes pre charged with refrigerant
  
• In theory easier to DIY
  
• Requires glycol
  

Split System

• Refrigerant runs between evaporator outside and condenser inside (like traditional AC)
  
• Harder to DIY, need gauges, refrigerant, more knowledge. EPA says you need license.
  
• Should NOT require glycol if used for heating only (But Spacepak might require it anyway, see below)
  
• Requires glycol if used for cooling
  

https://forum.heatinghelp.com/discussion/193273/spacepak-split-inverter-heat-pump-sis-060a-glycol-head-loss
Do you have Glycol in your system now? Glycol opens a whole new can of worms.

Thanks for that info. Nope, I do not use Glycol at all, I never had a need for it really, but I know a lot of people around here do use it.

hot_rod

If you have low temperature radiant you have a better match for using an A2WHP.

This journal shows a system going on its 4th winter in upstate NY. Maybe a similar climate to yours.

These is maybe 12 ccA2WHP cold climate on the market now, contact a rep for a knowledgable installer.

https://idronics.caleffi.com/magazine/27-air-water-heat-pump-systems

jesmed1

One of the cold climate ATW heat pumps I looked at for our condo building was the Arctic 060ZA:

https://www.arcticheatpumps.com/specifications.html

Turns out it would have been too difficult to make it work with our old cast iron radiators, but since you have radiant floors, that's an ideal application.

Here's a discussion thread with some people who have installed Arctics and seem to have good things to say about them:

https://www.greenbuildingadvisor.com/question/im-looking-for-user-experience-with-arctic-heat-pumps

Prevch

hot_rod said:

If you have low temperature radiant you have a better match for using an A2WHP.

This journal shows a system going on its 4th winter in upstate NY. Maybe a similar climate to yours.

These is maybe 12 ccA2WHP cold climate on the market now, contact a rep for a knowledgable installer.

https://idronics.caleffi.com/magazine/27-air-water-heat-pump-systems

Thank you that is very helpful

Prevch

jesmed1 said:

One of the cold climate ATW heat pumps I looked at for our condo building was the Arctic 060ZA:

https://www.arcticheatpumps.com/specifications.html

Turns out it would have been too difficult to make it work with our old cast iron radiators, but since you have radiant floors, that's an ideal application.

Here's a discussion thread with some people who have installed Arctics and seem to have good things to say about them:

https://www.greenbuildingadvisor.com/question/im-looking-for-user-experience-with-arctic-heat-pumps

Thank you very much that is helpful