On January 16, 2020 at 19:40, davidcasemore said...
Two things:
1. Are you sure they mean "shut off the gas supply", or do they mean "shut off the furnace". Shutting off the gas supply could mean installing a motorized valve prior to the furnace. Shutting off the furnace would be done by putting the contacts of the relay into the thermostat wiring. Usually, shutting off the furnace is the goal - this is to stop smokey air from being distributed throughout the house via the duct work. This method shuts down the blower motor - whether it's for heating, cooling or just fan mode.
2. I don't think a standard smoke detector is designed to be installed inside of duct work. System Sensor, and many others, make duct sensors designed for this purpose.
[Link: systemsensor.com]Thank you for your response. The detector you linked to is the same one I mentioned in my post so at least I’m on the right track!
You make an interesting point about the gas. I took the guys description to mean the gas but it would be better probably to shut the whole thing down. The furnace has an electronically controlled gas valve in it already which I figured I would be able to interrupt using it’s trigger wire. But your suggestion makes more sense to me as it would work, as you pointed out, during either the heating, cooling , or just fan modes.
Thanks again.
Craig.
