uneven air flow problem

[Toby Taber]

Hello all. I have an add on wood furnace ducted to my existing heat pump ductwork. I have two heat pump circuits and I have an 8" lube run to each trunk. The problem I'm having is that one circuit gets too much air, and the other not enough. Would a plenum help this problem?

 

[Cheesecutter]

I would think so. Or possibly a damper in the stronger circuit to help throttle air flow might work.

 

[cus_deluxe]

how many heat runs on each trunk? return air is also a consideration for any forced air system. yes a plenum should be installed for sure

 

[Toby Taber]

I have also read that I should isolate the A-coil from the heated air. My intention was to use the heat pumps as backup. How would you suggest that I do this?

 

[cus_deluxe]

i guess i dont know what you mean by "isolate the A-coil from heated air". In any heating/cooling system i have ever worked with (not many haha) the indoor coil sits directly on top of forced air unit, which is why they need to be cleaned every so often. once again, how big is the house, how many heat runs, how many cold air returns (and how many in each zone) these answers will help.

 

[brenndatomu]

Can you put a simple manual damper in line(s) to force the airflow the where you want it?The A coil shouldn't be a concern unless it is sitting in a plenum on top of the wood furnace. Heat pump will work as an automatic backup simply by lowering the thermostat set temp a few degrees lower than where you keep the house temp with the wood heat

 

[Toby Taber]

Let's see if I can give a better description. I have two heat pumps ( 2 ton & 3 ton) heating a total of 2500 Sq. Ft. The 2 ton unit has 8 runs and heats 1000 sq. ft. approximately. The 3 ton unit has 10 runs and heats 1500 sq. ft. approximately. I am contemplating building a plenum equal to the size of the top of the wood furnace and at least as tall as the top is deep. Then I plan to locate the plenum at a point that the runs I would need to tie it in would be equidistant from the plenum. Now, should I use two 8" runs to each heat pump trunk? I should also point out that each heat pump has its own air return and the wood furnace uses ambient air as the return.