heat pump: coil placement with gas furnace

[jcm55]

Looking for some advice on placement of a heat pump coil with an existing gas furnace:

Option 1: Standard placement above upflow furnace, gas burner runs during heat pump defrost cycle. Problem: high pressure at compressor, possible early failure

Option 2: Standard placement above upflow furnace, gas burner does *not* run during defrost cycle (blower only). Problem: cold air from registers during defrost

Option 3: Evap coil placement in cold air return plenum, before furnace. Problem: air flow can blow coil condensation through furnace, leading to corrosion of internal components.

[t527ed]

option 4: coil on top of furnace where it belongs with tempering control to allow gas furnace to run during defrost.............


fuel gas code does not allow coil to be before gas furnace unless manufacturer has approval to do so.

[beenthere]

Coil on top, burners run during defrost.
Unless your furnace is over fired, it won't cause high pressure back at the compressor.

[tinmantu]

Based on his post on another board recently, he wants to do it himself and has no clue of what a fossil fuel kit is...I told him on that board to hire a pro.

[beenthere]

After he cost himself a few extra thousand bucks, he''l learn its not as easy as just reading instructions.

Wait till he gets to deciding if he wants TT defrost, or Ondemand