A Strange Pir Problem

[Alarm boy]

Ok so this is a new one on me and i cant think of any resonable cause. I get called out to a system we installed a year or two ago and cust had used it no pobs ever since, however now for some reason when night setting and leaving hall the kitchen would pick up. But this PIR faces away from the hall mounted on the wall above kitchen to hall door in corner. So i check that the kitchen PIR hasnt been mixed up with another zone..nope. no cables are under the hall floor either. So i changed PIR over for a proven working one from same system & same problem. Basicly i can put system on walk test and move around hall i trip hall then walk a bit further and the kitchen goes (theres sod all in the kitchen). So then i go into kitchen and stand still watching the damm thing and nothing happens until customer moves in hall and i see the LED come on, this happened consistenly on any movement in hall. And they never have any problems with faulse alarms during the day or night

So its not a cable fault and its not detector fault its almost as if PIR is looking backwards.???????????

Parts being used are a Pyronix KX15DQ and a Texecom Premier 24 in a small 3 bed semi nothing special on system 7 Zones in total. Kitchen is aprox 8x10ft with a glass patio door at rear leading to a conservatory, i covered this over with a dust sheet incase this was causing some kind of reflection. This also cannot be a heat/sunlight issue either as the problem was first noticed at night whilst setting night set.

[ian.cant]

Shut the kitchen door...........................?

[A-G]

Air in kitchen is cold, air in hall is warm, movement in hall pushes a block of warm air into kitchen & triggers sensor ???

That's the only scenario I can think of. Try a D/T.

[black knight]

Have you tried covering up the sensor so it can,t see anything then repeating your experiment - that shouls prove whether it is enviromental or system.

beyond that try using a piece of cable from c/u to sensor just laid across floor temp., if poss, and again repeat experiment. again this will give you indication of direction you need to go. I suspect some kind of weird short is happening which is why i reccomend the above.

AG's suggestion of a d/t is also a way to go but it does,nt really give you a answer to whats causing it - this kinds of faults are the ones i like, they make you think.

good luck and let us know the results of your investigation

Paul

[Guest RJBsec]

Had a similar case where customer walked past open kitchen door to go to bed and pir triggered, shutting door cleared the problem. There was a mirror on the wall opposite the pir and the kitchen door which 'picked up' the customer as she walked past - the mirror or AG's air movement? ... Don't know but shutting the door fixed it!

[lawandorder]

Have you tried covering up the sensor so it can,t see anything then repeating your experiment - that shouls prove whether it is enviromental or system.

beyond that try using a piece of cable from c/u to sensor just laid across floor temp., if poss, and again repeat experiment. again this will give you indication of direction you need to go. I suspect some kind of weird short is happening which is why i reccomend the above.

AG's suggestion of a d/t is also a way to go but it does,nt really give you a answer to whats causing it - this kinds of faults are the ones i like, they make you think.

good luck and let us know the results of your investigation

Paul

I wonder if this could be reflection from a kitchen cupboard door or even a tiled floor, it does sound really weird!

Used to be a common problem with ultrasonic detectors but never come across it with PIRs.

[motco]

Used to be a common problem with ultrasonic detectors but never come across it with PIRs.

Oh, and microwaves...

[Alarm boy]

I will try a DT upon next visit unfortuntly i didnt have one on me that day. Closing the kitchen door prob will help if not prevent this issue however there is not glass in the door at mo and hasnt been for some time by the looks of it and this prob has on recently arisen (apparently). However i do feel that the door should be able to be left open just like all the others of the hall on the same job as its bound to be left open from time to time!

I still havnt attended yet as cust is away but hopefully a d/t will solve it. i shall let you all know

thanks

Air in kitchen is cold, air in hall is warm, movement in hall pushes a block of warm air into kitchen & triggers sensor ???

That's the only scenario I can think of. Try a D/T.

I see what your saying but somehow i dont think its the prob as hallway movement as little as 1 footstep to the left or right will trigger the kitchen pir just as if it were facing the hall! very odd, will try d/t.

[hpotter]

When you swapped PIR for another known ok in the building I take it you just swapped the pcb. It might be worth turning the back plate slightly so the "fingers" arnt looking down the same lines.

Fitting a different type/make of detector would in effect be doing the same, (unless your unlucky).

Just one other poss, - do they have one of those plug in rodent deterents thingymejigs in the hall? Had that recenly when they move RX40 picked them up even though they not visable to it!.

[Alarm boy]

When you swapped PIR for another known ok in the building I take it you just swapped the pcb. It might be worth turning the back plate slightly so the "fingers" arnt looking down the same lines.

Fitting a different type/make of detector would in effect be doing the same, (unless your unlucky).

Just one other poss, - do they have one of those plug in rodent deterents thingymejigs in the hall? Had that recenly when they move RX40 picked them up even though they not visable to it!.

Dont remember seeing a rodent detector although will check on next visit. but as i say i have stood still away from the detector and its fine (no LED indication at all) as soon as you slightly move in the hall behind it the LED comes on every time! yes i did just change the PCB in the detector. Are you saying i should slightly relocate the detector?

even pyronix dont know.

Im starting to belive the saying "iv got eyes in the back of my head"

for the replys