Do I have a Heat Pump issue??

["Hi-Viz" Bill]

Ok, I'm looking to tap into the vast knowledge base of this forum !! .. We purchased our new landmark 365 Newport in May, it had 3 AC units on roof .. we had our dealer replace the center unit with a AC/Heat Pump .. So now, in late November in Michigan, we're hooked up to 50a at the house, to load up for our trip to AZ, after I retire in a month .. the RV is winterized, but have been running the heat pump to take the chill off inside .. the thermostat is at 50 deg ... The weather here the last week or so has been in the mid-30s overnight, and this morning I discovered the roof unit was "caked with ice" !! I immediately shutdown the unit .. My question is .. Do I have an issue, or is it "normal" to have an ice buildup??? I assume the ice drastically reduces the efficiency of the unit ?? .. thank anyone in advance.

 

[sengli]

In past threads, others have mentioned that heat pumps first off are very in-efficient. Secondly they arent of much use below 35 to 40F.

 

[RoadJunkie]

Google "heat pump icing" and you will find that some ice build up on the coils is normal and the heat pump should have a defrosting mode to compensate. Total ice-up can be damaging. I would be interested in knowing if the roof units have a defrosting mode. Do you know the make and model of your unit?

 

["Hi-Viz" Bill]

Google "heat pump icing" and you will find that some ice build up on the coils is normal and the heat pump should have a defrosting mode to compensate. Total ice-up can be damaging. I would be interested in knowing if the roof units have a defrosting mode. Do you know the make and model of your unit?

It is a Dometic .. Do Not know model # yet .. Unit brand new this summer !!

 

[Bohemian]

Heat pumps are highly efficient. Using 1/10 to 1/15th the el3cteucity of electric resustance heating.

Alas, they condense water onto the cold exterior coils and eventually freeze up in near freezing temps.

 

[tlassen]

The heat pumps we have had were not recommended for use much below 45 degrees. Damage can occur

 

[danemayer]

Given the way the defrost cycle is described below, and the temps you mentioned, I'm wondering if yours was set up correctly by the dealer, or if perhaps the defrost cycle isn't running normally.

DEFROST CYCLEThis cycle is active during HEAT PUMP operation and allows the
heat pump to operate down to 30°F. When the outside ambient
temperature is less than 42°F and greater than 30°F, a defrost timing
cycle will begin. The defrost timing cycle will allow operation of the
heat pump for 25 minutes. The fan will then be shut off, the refrigerant
flow reversed and run for 4-1/2 minutes, this is the DEFROST cycle.
The refrigerant flow will then be returned to normal and, after a 30
second delay will continue until the temperature is greater than 42°F
or until the temperature becomes less than 30°F, at which time the
furnace will activate. (See AUX. HEAT). During the defrost cycle, the
DEFROST indicator on the LCD shall be illuminated.

 

[Bohemian]

Defrost cycles have their limits.

See instruction manual.