Added a combustion air duct, how to wire a vent dampener for it?

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sixplex
sixplex Posts: 182
in THE MAIN WALL

My boiler never had a combustion air duct, just an opening up high. It ran fine for 20 years, but it wasn't i ideal (sewer smell when it ran for too long, exhaust fans struggling, etc) So i added one, not sure how to wire a vent damper i got for it.

Vent damper: ARD12TZ, normally open, 24v to close, 2 contacts.

Relay: Tekmar 003.

When I connect the relay coil directly to a transformer it works fine and closes the ARD12TZ.

When i connect the relay coil in series with boiler demand which Tekmar 256 closes, the relay buzzes and chatters, the damper on the flute also makes noise.

Tried a 40va transformer instead of the 20va, it didn't fix it.

What am i doing wrong, how to wire it?

Comments

  • EdTheHeaterMan
    EdTheHeaterMan Posts: 12,880
    edited October 23

    First of all, the ARD12TZ is not the correct control for operating a combustion-air damper in this application. It has only two wires for operating the motor. You need a damper with at least four wires: two to operate the motor and two connected to an end switch.

    That end switch must close (turn ON) when the damper is fully open. This is a safety feature that allows the burner to operate only when the damper has reached the required open position. If the switch does not close (stays turned OFF), the burner cannot operate.

    You want this safety feature so the burner cannot operate when the damper is closed, because there would be no combustion air or makeup air available.

    Second: you need to have the motors in parallel. not in series. If you insist on using the incorrect ARD12TZ, you need to power the motor when the burner is not operating and remove the power so the damper opens on a call for heat or a call for the burner to operate specifically.

    This would be a better damper for your application if your air intake is 6" diameter Field GVD-6. The motor on this damper comes available on many different size dampers. Let me know what your air intake duct size is and I can help you select the proper damper for your application.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

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