You need to prove if it's environmental or the device.

Swap it with another or cover it from the environment.

what controls is on ?

 

is it on the main board or an expander or off keypad?

Have you got one in the other room back to back with each other?

 

Was going to say, re. controls, we had one like this once; mega rare (esp for old school Gardtec) but it turned out to be the zone itself (having defaulted the system twice and changed / adjusted / masked PIR twice).

TBH it only went on for so long as the client was over the road from the office and also bosses mate (I was getting paid but he wasn't paying), was really surprised when it turned out to be the zone though.

Edited October 22, 20178 yr by datadiffusion

Just tried swapping with a new old type (new but without the onboard resistors) can't see it working, it was originally on a panel cct then changed it to a zone expander Cct when this problem started to try and prove the fault with regards to location not back to back different rooms pointing away from each other it's even wired just across the tamper and normally closed terminals (without the anti mask connected ) 

Panels a menvier m1000 

I have got a detector upstairs same wall adjacent this one (would be looking at each other minus the ceiling) microwave penetrating floor causing interference perhaps? Clutching at straws 

33 minutes ago, Ashton said:

Just tried swapping with a new old type (new but without the onboard resistors) can't see it working, it was originally on a panel cct then changed it to a zone expander Cct when this problem started to try and prove the fault with regards to location not back to back different rooms pointing away from each other it's even wired just across the tamper and normally closed terminals (without the anti mask connected ) 

Panels a menvier m1000 

 

Interesting, the only other panel I've had spurious zone faults with since is the M series / x5n series! However, in that case it was on the expanders in the first place and swiftly dealt with by junking the panel (and no issues since on same wiring / detectors).

I agree that's why I changed the Cct over had similar myself but I ended up re using the panel Cct for a psu tamper and never had any issues since with that Cct the only time it seemed to make a big difference is when I turned the microwave right down and reduced the pulse count with dipswitch one had it on soak and passed that after 2 weeks then did it again not long after 

51 minutes ago, Ashton said:

(without the anti mask connected ) 

 

does the alarm relay also open on AM ?

 

is the sensor nr a door ?

 

Just a thought had a new boiler done and the wireless thermostat is sat on a unit facing the detector its 868mhz frequency again clutching at straws anyone know the Honeywell microwave frequency range and isn't facing a door but front door is within detection range 

And that's a good point actually regarding anti mask/self test would have to try and look in the destructions maybe a device fault opens the relay