Temp. drop during defrost

[lma]

I have a FRHS0301 unit outside & a AH14X1ona air handler with a 3610-610 heater assembly.
had the defrost board replaced but new one is not demand defrost.When in defrost mode with low
outside temps., the inside temp drops several degrees below set point.This causes the heater to stay on to compensate. This wasn't bad with the demand defrost, but new board is time controlled.

This unit has a 10KW heater with a optional space.Would changing to a 12.5-15.0 KW heater help
prevent this temp. drop? Can this be done without changing the control board?This problem is worst
when the unit cuts off while in defrost mode.

[Robert]

Hi,

Who replaced the defrost board ? They should have ensured all was working correctly. Any time the system goes into defrost, the AHU heat strips should come on and remain on while system is in defrost.

I would have them come out and resolve this issue.

IF the temps are too low, the heat strips will be on a lot more as the heat pump will not produce adequate heat in low temps.

You can get higher kw heat strips, but may need to upgrade the sequencer or contactor.

Would also have to ensure the breakers or fuses can handle the higher amp loads.


Again, an hvac tech would be needed, preferably the installer of the defrost board.



Thanks,
Robert




Thanks,
Robert