Jump to content
Security Installer Community

A Strange Pir Problem


Alarm boy

Recommended Posts

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.

cheers

Ryan Williams - South coast service engineer for Banham Fire & Security Group*

*Comments are my own and do not reflect those of Banham Fire & Security Group.

Link to comment
Share on other sites

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.

.

.

.

PM me for access to the SSAIB members discussion area.

Link to comment
Share on other sites

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

THE BLACK KNIGHT

"Any comments / opinions posted are my opinion only and do not represent those of my employer or Company."

Link to comment
Share on other sites

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!

Link to comment
Share on other sites

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.

Link to comment
Share on other sites

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.

cheers

Ryan Williams - South coast service engineer for Banham Fire & Security Group*

*Comments are my own and do not reflect those of Banham Fire & Security Group.

Link to comment
Share on other sites

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!.

post-17665-1234892462_thumb.jpg

Link to comment
Share on other sites

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!.

post-17665-1234892462_thumb.jpg

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"

cheers for the replys

Ryan Williams - South coast service engineer for Banham Fire & Security Group*

*Comments are my own and do not reflect those of Banham Fire & Security Group.

Link to comment
Share on other sites

Hi,

Just a quick question...

Is the PIR wired using common wiring? i.e. + & - and one zone wire?

(This was often used in the old days, to save on wiring)

Similar problems can also be encountered using keypad zones.

What happens is that when the one PIR triggers, it effects the voltage on the other. Because this is connected to the zone, it can effect the zones resistance (V=IxR), causing the 2nd PIR to go into alarm.

Probably not the case...

n

Link to comment
Share on other sites

Hi,

Just a quick question...

Is the PIR wired using common wiring? i.e. + & - and one zone wire?

(This was often used in the old days, to save on wiring)

Similar problems can also be encountered using keypad zones.

What happens is that when the one PIR triggers, it effects the voltage on the other. Because this is connected to the zone, it can effect the zones resistance (V=IxR), causing the 2nd PIR to go into alarm.

Probably not the case...

n

Good point. Did Alarm Boy mask off the hall detector during the process of elimation steps to ensure it was the not the hall PIR influencing the kitchen PIR before looking for the reflections, etc?

There's no substitute for experience .......... so all opinions welcome!

Link to comment
Share on other sites

Good point. Did Alarm Boy mask off the hall detector during the process of elimation steps to ensure it was the not the hall PIR influencing the kitchen PIR before looking for the reflections, etc?

Run that past me again?

How can one PIR influence another PIR?

Link to comment
Share on other sites

Run that past me again?

How can one PIR influence another PIR?

I think (though I shouldn't assume) that he means that the hall pir is triggering thus drawing more load which in turn is causing a voltage drop to the pir in the kitchen causing it to trigger.

I can't think of a better explanation (apart from reflection as mentioned earlier) but I think it's highly unlikely given the tiny ammount of current that the average pir uses.

First thing I would do is mask the kitchen pir, if it cures the problem then it's got to be reflection.

Bear in mind most solid objects don't allow infra red to penetrate or at least not in the frequency range that pirs are sensitive to, on this basis solid objects must either absorb or reflect the ir.

Link to comment
Share on other sites

Run that past me again?

How can one PIR influence another PIR?

He's talking about an unconventional way of wiring PIR's .... At each pir fit a link from + to C, then connect zone wire to NC. This would mean that the common + wire is supplying 12v to several PIR's and the + to each positive alarm terminal, thus when one PIR goes into alarm there is a possibility of a volts drop to the positive alarm terminal in other PIR's.

Clear as mud?

.

.

.

PM me for access to the SSAIB members discussion area.

Link to comment
Share on other sites

Hi,

Just a quick question...

Is the PIR wired using common wiring? i.e. + & - and one zone wire?

(This was often used in the old days, to save on wiring)

Similar problems can also be encountered using keypad zones.

What happens is that when the one PIR triggers, it effects the voltage on the other. Because this is connected to the zone, it can effect the zones resistance (V=IxR), causing the 2nd PIR to go into alarm.

Probably not the case...

n

So why is it ok with the door shut?

The opinions I express are mine and are usually correct!

(Except when I'm wrong)(which I'm not)

Link to comment
Share on other sites

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"

cheers for the replys

Yes, either move back plate to see if picking up reflected IR, or re-site detector within same room. As you have swapped for a known good detector (& presume no probs with where you swapped from) so better to use proven than get new unproven if you see what i mean.

Cost = nil also :)

Link to comment
Share on other sites

So why is it ok with the door shut?

I did not recall reading that it was ok with the door shut? But you seem to be an expert, so I will bow to your superior knowledge, and the fact that you may be more literate than me. Your tag line clearly states that you are more knowledgeable than me..."The opinions I express are mine and are usually correct! (Except when I'm wrong)(which I'm not)" I just wish I knew as much as you do. And I just hope that when I do, I am able to stay humble....

All I asked was, was it wired right? I had a similar problem once, and this was the problem.

I was just trying to help. I have learn't that I don't know everything, and that I can learn every day, sometimes from surprising sources....

Sorry, for my suggestion. I retract it. Perhaps you can assist in solving the problem, as opposed to just critising suggestions?

NN

NN

Link to comment
Share on other sites

I did not recall reading that it was ok with the door shut? But you seem to be an expert, so I will bow to your superior knowledge, and the fact that you may be more literate than me. Your tag line clearly states that you are more knowledgeable than me..."The opinions I express are mine and are usually correct! (Except when I'm wrong)(which I'm not)" I just wish I knew as much as you do. And I just hope that when I do, I am able to stay humble....

All I asked was, was it wired right? I had a similar problem once, and this was the problem.

I was just trying to help. I have learn't that I don't know everything, and that I can learn every day, sometimes from surprising sources....

Sorry, for my suggestion. I retract it. Perhaps you can assist in solving the problem, as opposed to just critising suggestions?

NN

NN

Sorry if you took offence and threw your toys out of your pram, It wasn't a personal criticism of you, just an observation.

Had a bad day???

The opinions I express are mine and are usually correct!

(Except when I'm wrong)(which I'm not)

Link to comment
Share on other sites

Sorry if you took offence and threw your toys out of your pram, It wasn't a personal criticism of you, just an observation.

Had a bad day???

now now children

Ryan Williams - South coast service engineer for Banham Fire & Security Group*

*Comments are my own and do not reflect those of Banham Fire & Security Group.

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.