Cold Climate Heat Pump Coil

DavidSa

Is there a difference between a cold climate coil and a standard coil?

I’m planning to install a 3t Resolute cold climate heat pump but my furnace and plenum are way oversized for my house, creating unexpected issues. Thus regularly-sized 3t coils are physically too small and we need a larger coil (24” I think?) but still only 3t. The plenum is sized for 5t. 

The problem seems to be that Trane doesn’t make a large-body 3t cold climate coil so we are considering installing a large, standard-climate 3t coil instead, which is available. 

We are installing the heat pump to provide energy-efficient and green-house-gas efficient heating to supplement our (oversized) furnace, in a cold climate (Canada). 

We want to proceed if the standard coil works just as well with cold ambient temperatures and the Resolute HP, but don’t want to proceed if it compromises the energy/GHG-efficiency or the ‘cold-climate’ aspects of the Resolute.

I’m not sure I phrased the question the right way and I don’t yet know the model number of the available coil. 

Regardless, does anyone have a comment?
Thanks.  

EdTheHeaterMan

You can do wonders with sheet metal. Cut the plenum open to install the coil, place a pan horizontally in the plenum about 3" above the furnace outlet. Cut a square out of the middle of the pan to accommodate the coil opening. Place the coil on the pan. Then put a sheet metal cover on the opening of the plenum. Seal with mastic or mastic tape. Insulate as needed.

bburd

@EdTheHeaterMan 's advice above is excellent. You may have to adjust the blower speed to compensate for the restriction in the plenum. External static pressure should be checked once the modifications are done. Also if you are keeping the gas furnace, recheck the temperature rise with the gas burner on against the manufacturer's specification.