Hi,I also never wired a duct smoke detector but A my friend suggest me for the wiring of the smoke detector,so Determine the smoke detector's input voltage. The fire alarm system's control panel, located near the air handler, lists the smoke detector's input voltage and labels the control system's wire terminals. Usually two sets of wires extend from the management panel's wire terminals. One set leads to the smoke detector's input power supply and the other leads to the smoke detector's alarm circuit. In some cases, the smoke detector receives its input power from the air handler. Check the control panel's wiring diagram to verify the input power's source.so may it prove helpful for you.thanks
if this is a commercial unit. the power will come from the fire panel and also have a battery back up. I have never seen power supplied form any other source. The battery back up should maintain a charge for at least 90 minutes in the event of power loss.
im still learning bout these duct detectors too they can be easy to diagnose or very troublesome i actually ran into one that was dropping my 24v to my unit i noticed when blower contactor was pulled in after a min of running would start to chatter n i would get 10v but my transformer would still have 24v supply i trying sever things to figure out what it was long story short it was the duct detector i unhooked the common and unit ran fine. usually when i get into an issue w a duct detector i hvae the alarm company come out too becuase they are the ones that hook the detector up.
Here's a question I've always wondered about; If the duct detector only kills the 24v signal (opens R) what happens if the unit is running in heat and the blower is already running? The blower will eventually time out but it will continue to fan the flames until then, right?