Device to monitor fireplace chimney flue

There is a manual damper at the top of my vented gas fireplace box. It’s a simple arm you push forward and up to close and back down to open. I have the fireplace controlled on/off with a Homeseer lfm20. I simply want a device to check if this is opened or closed when the fireplace is on or off respectively. Seems like a door sensor would melt under these conditions.

Any advice?

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Maybe you could simply mount a door sensor on the arm instead of the damper, if the arm is in a place that stays relatively cool. Alternatively you could buy a reed sensor, wires, and magnet rated for high temperatures and mount those inside the flue, then wire the reed sensor to the door sensor (replacing its own internal reed sensor).

Is there anything on the outside of the flue from which you could infer the position of the damper, something like a rotating hinge pin?

A Carbon Monoxide detector either way of course…

But you could also use a sail switch that would be drawn back with the flue drawing combustion air to the logs. Most of these have a very thin piece of sheet metal (usually aluminum) that should hold up to some heat as long as you can get the switch its self mounted away from the heat. Which could then also be connected to a door switch in the place of its regular reed switch.

Actually it looks like the damper rotates on a hinge, can you provide a link to what I would need to do this?

If you can access the hinge pin from outside the flue (where it’s cool), you could simply attach a mercury switch to the pin so that when the damper opens or shuts and the hinge pin rotates, the mercury switch is rotated along with the pin and opens/closes. Attaching the switch to the hinge pin might be tricky since you’ll want to thermally isolate the switch from the hot pin.

Anyway, maybe you can post some pics of the damper, the hinge (on the outside of the flue), and the handle that operates the damper. That’ll help us to come up with a way to fix a detector to it :slight_smile:

I see, access from the outside of this is not possible because this is a full stone surround, no way to get in that part… we’ll definitely need some type of heat resistant sensors. I have 3 extra wires from the security cable (5wire) that are running from the inside of the fireplace to the outside where the LFM20 module is so we could utilize that.