Heat pump condensation

[USMCRET]

Just a curious question and/or observation; I noted that when my heat pumps are heating, condensation forms and drips off the roof like it does when they are in A/C mode. I have not noticed this with my home units. It doesn't make sense to me that they would do this. Anyone care to comment?

[C-PHartley]

I would guess that what you are seeing is water that is actually melted ice from when your unit goes into a defrost mode. It is normal for reverse cycle A/C unit to ice over and need to defrost. when this happens, you may notice cold air coming from the vents as the unit is actually running in the a/c mode.

[GaryKD]

Hi USMCRET,
I have the same coach as you. Mine do the same thing. I have never thought about it.

[TXiceman]

When running in heat pump mode, the coil on the roof is actually the evaporator. If the outside air has enough moisture, ie dew point is high enough, the moisture will condense on the coil just like in A/C mode. Additionally, if the coil ices, it will melt during the defrost.

Ken

[Mr_D]

I've seen condensation run off our our home heat pump coils.

[USMCRET]

I figured this was normal, but my abnormal curiosity wouldn't leave it alone. Thanks all.

[RustyJC]

The heat pump extracts heat from the outside air by cooling it and transfers this heat to the indoors. The exterior coil becomes the evaporator, and the interior coil becomes the condenser.

If, for instance, the outside temperature were 45 degF and the dew point was 40 degF, the heat pump might chill the outside air passing over the evaporator coil to, let's say, 35 degF. Since the dew point is 40 degF, condensation would form and run off the RV's roof, but it's forming on the opposite coil (i.e., the "exterior" rather than the "interior" air coil) than would be the case during AC operation.

Rusty