Vent Damper Check


Old 12-04-16, 02:53 PM
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Join Date: Dec 2016
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Vent Damper Check

Gang -

Another boiler question for you.

Moved into a house that has a fairly modern boiler which was installed in 2010. It has an automatic vent damper that someone had cut the wires to and bypassed (basically rewired it) while the vent damper is now stuck in the open position.

I'm presuming that someone did this because the vent damper motor no longer worked and this was a cheap fix. (not sure why someone else would do this?)

Buying a new vent damper motor is around $90 + the general agony of fixing the wiring.

Does anyone know an easy way to test the functionality of an automatic vent damper without going through the trouble of hooking it back up?

Also not quite sure of the value of the vent damper and if this would pay for itself in energy savings...


It's one of these:
46491600 - Field Controls 46491600 - Vent Damper Motor Assembly - Plastic Base
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Old 12-05-16, 05:28 PM
Join Date: Apr 2014
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I have 2 Field Control dampers. The easiest thing to do is remove 2 Phillips screws that hold power head to stack and remove it. Find some way of clamping damper shaft in open position.

Power unit with 24 VAC on bench to check it out. It could be that someone cut the wires as part of a trouble shooting action. Check the status of the "manual on" switch on the board and whether it works.

The value of stack dampers is reducing standby/latent heat losses when boiler is off. One study I recall found a 12% reduction in heating costs on Alaskan schools that used them. I think they are especially good for round water heaters.

Stack vents act like a "heat pipe" and draw heat out of static boilers and water heaters. Electric dampers prevent that. I also wrap the vent pipe with insulation from where it exits the boiler to stack vent. For a dollars worth of insulation the payback is endless.

Last edited by doughess; 12-05-16 at 06:31 PM.

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