We have a new account that has three duct detectors displaying an output abnormal trouble. All three have a blinking red led on the board and the amber trouble led is not lit up. Did a warm reboot and the troubles returned but not a cold reboot because we cannot locate the breaker for the panel yet. Does this indicate that the duct detector housing or sensor needs to be replaced? Thanks!!
This can occur after years of vibration from a HVAC system causes some of the screws on the inside of the unit to back out and stop the connections between the PC board ↔ detector head & base from making good contact. See this video for a more detailed explanation.
From what I can tell, there doesn’t appear to be a way to remedy the issue without replacing the entire duct detector assembly, because to repair the aforementioned screw issue, you have to peel some foam backing away from the unit, which doesn’t come off cleanly.
That being said, though, this may not be the exact root cause. It could also be the detector head inside the unit OR the PC board going bad.
That variant has a relay built in that requires a 24v power circuit. When that circuit is disconnected or not providing enough voltage it will show that trouble.
Model 4098-9756:
x Duct sensor housing with supervised output for
multiple remote relays; requires separate 24 VDC;
includes one relay
x Relay output is under panel control
x At the panel, relay output can be activated manually or
in response to a separate alarm or other input
I agree with Long john. Especially if three went into "output abnormal " at the same time. Look at what supplies the separate 24 volts to the detetcors.
Thanks for the replies. I think you guys may have figured it out. There was another problem that I didnt mention. A door holder went bad and it was dragging down the aux power from the panel to about 7vdc. I replaced that and power restored to 30vdc then I looked at the duct detectors. They had 30vdc when I checked them but wonder if they may have restored by now since it has been a couple days? Thanks!!
1 Like