Horizontal twinned furnaces

Ac226 · September 20, 2021, 08:57:16 PM

Hello, I will be installing two Carrier 100k btu furnaces twinned together. They will be a horizontal application I have read and looked up the installation manual for the twinning but it only shows the furnaces together with there backs together and facing away from each other or stacked on top of each other. Unfortunately we do not have the height to stack or the room to put the backs of the furnaces together. Is there any issue with having the fronts of the furnaces face each other but staggered one further down than the other which would mean that the plenums on the supply and return airs would be of different lengths before they connect to the common duct there will also be two 4 ton slap coils on each furnace. My question is that will the different length of plenums cause any issue with airflow or operation before it gets to the main trunk line. Thank you in advance!

Sergroum · September 21, 2021, 10:59:07 AM

I don't think so.

Are you using infinity control with mn7, or tn6?

Ac226 · September 21, 2021, 02:57:12 PM

No there just single stage non communicating

Admin · September 21, 2021, 05:23:37 PM

Model number?

Ac226 · September 21, 2021, 08:53:10 PM

The furnaces are carrier 59SP5A. single stage heating and ECM blower.

Admin · September 22, 2021, 06:01:27 AM

You will have a hard time getting the external wiring harness to reach but I don't see that it can't be done. See attached.

Sergroum · September 22, 2021, 08:38:19 AM

Yeah. As long as each furnace is capable of 1600 CFM, it'll likely be okey. It won't do any static resistance checks and detect nonsensical problems. As long as you'll manage to wire it up neatly.