Old VariTrane Dual Duct VAV System with Tracer Summit UCM I Controllers

[apprentice3]

Today I had to go to an old building with some really old VariTrane Dual Duct VAV boxes sitting under an older Tracer Summit system. This system is utilizing some very old UCM I boards. According to the wiring diagram, these VAV boxes contain (2) UCM I boards (one for the heating damper and one for the cooling damper). I have tried to find documentation online without success. I can't find much on Trane's old dual duct boxes OR the UCM I control board (everything shows the UCM IV board). Would anyone have any information on these?

These dual duct VAV boxes also utilize some sort of dual zone sensor. It appears like one sensor goes to the heating UCM board and the other sensor goes to the cooling UCM board. Does Trane offer a direct replacement for this sensor type (part number X13510348-03)? Or do they just want you to parallel/ daisy chain the zone temperature sensor from the heating board to the cooling board?

I also have some questions about how the setpoints need to be arranged on these dual duct VAV boxes.

• As mentioned above, each of these VAV boxes have (2) UCM boards. I have found that the thumbwheels are disabled on all of them. The UCM boards are integrated into the Tracer Summit system separately. They show the heating board and cooling board in the navigation tree. What is the recommended way to define the occupied heating/ cooling setpoints between the two boards?
• I ran into some UCM boards that had the occupied cooling/ heating setpoints set higher on the heating damper board than the cooling damper board. This makes no sense to me. It seems like the two dampers would fight one another. The heating damper and cooling damper have the ability to modulate from minimum to maximum independently from one another. With this being said, I would assume that the setpoints between the boxes would either need to match or have the setpoints on the cooling UCM board set a little higher than the heating board.
• I found that the only real difference between the two boards is one of them constantly shows a air valve control action of heating and the other shows a air valve control action of cooling. I assume the heating board resets its airflow setpoint to maintain the active heating setpoint while the cooling board reset its airflow setpoint to maintain the active cooling setpoint.

If anyone has any information on these old dual duct VAV boxes, UCM I controllers, and zone sensors that would be appreciated.

[roadgear16]

Sent an applications manual for the old VAV stuff to your email. That's some old stuff there. Good luck.

[apprentice3]

Sent an applications manual for the old VAV stuff to your email. That's some old stuff there. Good luck.

I got it. Thank you for sharing that document! Yes, definitely some old stuff. I feel like this system must of had Tracer 100 on it at one time. The dates on some of these UCM I documents are from 1989. Thanks for your help!