Automatic Vent Damper Opening and Closing Constantly

danielha

I have a gas boiler for a radiant hot water system with 2 zones - 1 for radiators and 1 for in floor radiant. The in floor radiant was added a couple years ago and a two zone i-link pump controller was installed. Perhaps related, perhaps not, around this time the automatic honeywell vent damper started opening and closing all the time (and started squeaking, which brought it to my attention). It stays open and works fine when the thermostat is calling for heat, but when nothing is running it just slowly opens and closes over and over again.

I'm wondering 1) If this is likely to be a bad piece of hardware that I should replace or 2) someone messed up some wiring. If it's the wiring, I'm at a loss for what would be causing this constant cycling of just the vent damper when nothing is calling for heat.

Thanks! I've attached photos of the various parts.

STEVEusaPA

What kind of thermostats? If they have batteries I’d shut everything off and replace them with fresh ones.
If it’s not that, and you have no loose wiring/connections, then you’re going to need a meter and some troubleshooting skills.

Hap_Hazzard

Sounds like the sensor that detects when the damper is closed isn't working. When the thermostat is calling for heat, the damper will turn until the sensor that detects when the damper is open is the one that stops the motor, so the one that detects when it's closed is irrelevant.

Your control looks more complicated than mine, so I'm not sure how it works, but I see something that looks like a relay in the lower left of the picture, with a clear plastic case. If I had to guess, which I do, I'd say that's a SPDT relay that's energized when the thermostat calls for heat, and the contacts probably toggle which switch is "listened to." So either the relay contacts that connect to the "vent is closed" switch aren't making contact, or the switch itself isn't closing. Or something.

Hap_Hazzard

BTW, the squeaking is normal. I don't know why you weren't noticing it before, but they always do that.

danielha

Maybe I just noticed it when it started doing it every 5 seconds

Zman

If you disconnect the TT connections from the zone controller and the problem goes away it is an issue on the control side. If it does not, it is probably a bad actuator in the damper.

danielha

After some more investigation the wiring at the board seems pretty funky and slightly jarring it causes it to start and stop entirely. I'm leaning towards it being a problem with the unit itself. Are these things worth replacing? I have seen some comments that you might as well just jam them open and be done with it.

Hap_Hazzard

I think an automatic vent damper is worth having. Have you taken off that metal cover in the middle of the board and looked inside? I'm guessing that's where the position sensors would be.

unclejohn

If you are going to bypass the damper don't jamb it open. Remove the damper fully.

HVACNUT

The switch kn the right side, is that auto/manual?
You can switch it to manual and leave it open. You'll just lose some efficiency. .083% by my calculation.