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twinning furnaces

Hopeful
Hopeful Member Posts: 1
in Thermostats and Controls
COMMERCIAL APPLICATION

I HAVE 2 - 120 BTU FURNACES TWINNED ON A ZONED SYSTEM. THE PROBLEM IS WHEN ONLY ONE OR TWO ZONES ARE OPEN THERE IS A LOT OF AIR BLOWING THROUGH BYPASS. I WRAPPED THE ONE FURNACE FILTER IN PLASTIC TO STOP AIR FLOW AND DISCONNECTED TWINNING WIRE AND FAN WIRE FROM BOARD. I DO NOT NEED THE HEATING BTUS BUT I DO NEED FOR THE AC COILS. 2 -5 TON AC COILS ABOVE FURNACE. WHAT IS THE BEST WAY TO CONTROL FAN AND FURNACE WITH DAMPERS AND CONTROLS?

Comments

  • Ironman
    Ironman Member Posts: 7,538
    Question

    Why were the furnaces twinned if they're feeding separate zones? Please post a duct/ zoning diagram
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • John Mills_5
    John Mills_5 Member Posts: 952
    Zone panel?

    With the right panel you can control capacity through staging but since both blowers have to run together (unless you do like you did) excess airflow probably will still be an issue.



    Only question might be, and would take seeing a drawing, is if you can change things around so 1 system did the largest zone by itself and the other did the other 2. Just grasping at straws since I don't know the layout.
  • Empire_2
    Empire_2 Member Posts: 2,340
    Min Zone?

    Sounds like a possible design problem.  Even with the least amount of zones calling, there must be an exceptable min air flow to avoid this problem.  Can you slave 1 or more zones to say.....2 ton out put?  800 cfm will probably make the bypass not open as much.  Noise is the main problem, but you have to dump the air somewhere and that's whay I think this might help.



    Mike T.
This discussion has been closed.

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