I need a little help making sure my Trane XB90 furnaces are setup correctly. The furnaces are twinned now and using 1 transformer. On the terminal board of the furnaces the R/G/W/C (I think, I'll check when I get off work) are being used.
The wire connected to R splits/wired nutted and goes to the thermostat and runs to the condensate pump->condensate float switch->secondary furnace R.
The wires connected to C/G/W split/wired nutted and go to the thermostat and to the furnace respective to the correct colors.
The twin terminal is not being used on the board. The furnaces have different breakers but from the same feed. It seems like the twin terminal should be used but it might not matter. What is the functionality of the twin terminal?
The furnaces both come on together and are working. I tried just turning on the fans using the thermostat but they didn't work. I put a jumper across R and G on the stat and they came on so I think that the stat could be defective. The current setup the secondary furnace can be shutdown and the primary will continue to run. This seems like a problem to be because the primary furnace will suck air back through the secondary and cause the motor to spin in reverse. The air circulation through the house will be minimal.
When I had the units installed the Trane Salesman said that the furnaces would be staged. Currently they are twinned but I want to have them stage but want to make sure they are wired correctly.
In this thread
Twinned Trane XE80 issues
beenthere states that the twin wire is to synchronize the blowers of the furnaces. So is in possible if the twin wire is connected to run a wire for heating to each furnace from the stat? Will that keep the blowers running at the same time but allow them to be staged? Will the twin terminal also shutdown both units if one goes down? I couldn't find anything in my manual to explain how the twin terminal is used.
If the furnaces are staged then the 1st stage will get worked more than the second. To avoid this would you recommend installing a timer relay and set the accumulation time to 500 hours to have the stages switch?
This seems like it would work:
I have a Honeywell stat and don't really understand when the second stage will be called for. I read that the stat keeps track of how often heat is being called for to determine how long it should wait to bring on the second stage. Does anyone know the program for the logic?
That is a lot, sorry