Heat Pump operation below 32 degrees

[Darrell Terry]

Woke up this morning to 26 degrees in Eugene,OR.  Neither front or rear Heat Pumps would operate.
I have been in cold weather before and don't remember this being a problem.
Is there a temperature that Heat Pumps will not operate when below ?

Darrell

[David T. Richelderfer]

Below 35 to 40 F these heat pumps don't work well.  You have to use the Aquahot burner and the interior furnace-fans for interior heat.

[Darrell Terry]

Thanks David  -  They worked last week when temperature was at or near 32. 
Woke to frozen water hose as well. Will need to keep water dripping tonight if I get it un-thawed today.

[Joel Ashley]

I don’t know how they could’ve run at 32F.  Is your thermometer accurate?  They generally won’t run below 40-43F because there’s just not enough heat in the ambient air to exchange for.

If you’re going to try and save fuel money by heating with the heat pumps, at least monitor things enough that the hydronics can kick in too;  the bay thermostat turns that heat exchanger on at 40 but not if the hydronics are shut off.  You risk freezing the water lines and any susceptible components below the floor, perhaps in extreme conditions even the hydronic unit itself.

Joel

[William Jordan]

We are in Drain visiting relatives and heading south in the AM ! Newer "Home"  Mini splits can function down to the 20's due to new  Tech.... I'm having one installed in my Florida property..... However the basic A/c heat pumps in these Motorhomes can't work well down below about 35-40. A heat pump will always "work" at these low temps but its ability to provide useful warmth to overcome the outside ambient is marginal.
We always use the Aqua Hot furnace when Temps are low as it also keeps the pass thru bays/water lines( which are in my coach, are bundled with the Boiler lines)  warm.  As Joel says if the Aqua Hot isn't on it can freeze ... not healthy to your checkbook.
In freezing weather overnight , Turn off and stow your water hose and run off the internal tank. If you have tank heaters (I do) and are hooked up to power turn them on. 

[Darrell Terry]

Thanks for the information-  More questions
Is Electric function of HydroHot sufficient to keep basement and water tanks/lines from freezing ?
Or is the diesel function the better alternative in sub 32 degrees weather ?
Any idea which function is easier on the wallet. I'm aware that who pays for the electricity is a factor here.
In our current RV Park, I pay electricity but in Oregon it is not pricey. ( last month $38 )

[Stan Simpson]

I don't think the electric element heats the bays. If you have an Aladdin or Silverleaf, under the tank reading screen (on my Aladdin) there is a temperature reading for the inside, and the "basement", which is everything under the floor. I have always used the diesel burner in cold (below 32 temps). The coach sits next to the house, and I check it regularly when there is a possibility of below freezing temps. I set the furnace temp inside to 45 degrees, and each time I check, the house and basement are 45 degrees.

[Gerald Farris]

Stan,
The electric heating element in the AquaHot heats everything just like the diesel burner does because they are both heating the same antifreeze solution in the AquaHot that carries the heat to the induvial  heat exchangers throughout the coach. The difference is that the diesel burner produces a lot more heat than the electric element does. That is the reason that the electric element alone will only heat the coach adequately (72 degrees) when the out side temperature is above the 40 to 45 degree range.

Gerald

 

[Jerry Emert]

Just a thought!  I had the heat pumps on a lot in NE TN over the last few weeks.  My front unit developed a leak inside that I have not been able to figure out.  AC does not leak inside HP does.  Anyway I've done a lot of research because my HPs were working fine at 32-35 degrees.  What I found is that "they" say that they will continue working at lower temps but that the oil in the compressors is too thick and will ruin the compressor eventually.  So...something to think about.  On the bright side the 27 degree temp this morning forced me to turn on the furnace that I have not really been able to use in 6 years because of coolant leaks in exchanger hoses that emptied my reserve in seconds the last few times.  My last hose replacement seems to have fixed it!  Yay!!