PIR and boiler flue

[Andy Burns]

Ye olde style balanced flue terminal, not a combi/condensing plume. Would a 180° PIR sensor about 18" above and 18" to the side of the flue be likely to suffer from false triggering?

[A.Lee]

Yes.

[Brian Gaff]

And going rusty as well, most probably. Brian

[ARW]

The plastic PIR?

[Bob Minchin]

Very likely

PIR is looking for differential thermal movement. A 10' separation should calm it down considerably

I've got one on an intruder alarm that detects leaf movement when the sun is on the leaves and there is a breeze.

[Andy Burns]

Thanks all.

For "neatness" I wanted to place the sensor equidistant from the two lights it will control, but then I realised how close to the flue that would put it - it can get placed to one side instead ...

[Andrew Gabriel]

If it's an occupancy sensor, make sure it's positioned so it only 'sees' people in the room, and not people walking past outside. A typical position is near to the wall with the doorway, but towards other end of that wall if ceiling mounted, or better still, wall mounted on the wall with the doorway.

[Andy Burns]

This one is external and will only "see" people for whom it should turn on the lights.

I have also got a 360° occupancy sensor type to fit in the porch, which I was planning on ceiling-mounting, but can test blu-tack mounting it in various places first.

[burns.me.uk]

Well at the time, I went for 5' to the side and 18" above, and all had been well, until the clocks changed, since when the boiler started coming on af ter it's dark enough for the PIR to operate. I'd "caught" the outdoor ligh t on a couple of times when I didn't think it should have operated, just no w I forced the boiler on and stood by the back door watching, within two mi nutes of the boiler firing (but no vapour visible from the flue) the PIR br ought the light on.

Just a warning from history to anyone else searching this thread really, I can try to mask the PIR in the direction of the flue terminal ...