Too many false alarms - please help

peteuk · 7 Nov 2010

Hi,
Hopefully the people on this wonderful site can help me again.

When we bought our bungalow in 2005 one of the 1st things we did was get a burglar alarm installed. Unfortunately the installer has retired.
PIRs were installed in each room except where internal.
Over the years we have had 'false' alarms from our dining room during the night.
They rarely happen when we are at home, but mostly in the early hours of the morning when we are away.
It has happened on the last 2 occasions and we really can't expect our neighbour to switch off the alarm any more. (Age and health are against her)
Our 1st countermeasure will be to omit that zone in future but obviously we'd like a permanent fix.
Thinking it may be a spider we spray all our rooms with insect killer before we go away. This obviously doesn't work.
The PIR faces diagonally across the room but there is a large South facing window opposite. Our neighbour has a security light that unfortunately shines into the room (protected by vertical blinds only). However my understanding is that this is unlikely to be the cause.
I am struggling with the fact that the problem is intermittent and that it mainly occurs when we are away. (Or could that just be coincidence?)

Because the room is South facing with a large window could it be that temperature changes means we have a faulty PIR? If so, is replacement a DIY job and is there a preferred PIR type or make?
Failing that, if I ask another installer to look at the alarm system will they be able to find an intermittent fault?
Thank you

joe-90 · 7 Nov 2010

What kind of PIR is it? It may have an adjustable pulse count.

Spraying the room is no use it won't get to the spider.

Try this: Smear a very small amount of Vasalene around the edge of the sensor - spiders won't walk on it. If it still plays up then replace it.

Alarm · 7 Nov 2010

Spider could be inside the pir. Open it up and clean it out. Seal the cable entry with blue tac to prevent egress.
Then as suggested thin layer of vaseline around the edges.
The freznel lens on the pir could not be blocking the light correctly due to age.
What time do you know when the activations are.
One preventitive measure is to close the blinds or have them set to deflect the light when activated.
All of the above should cure the problem. If not time to replace with something new. If you are capable a decent hardwired pir ( I assume this is hard wired) can be picked up on the web for £15 for a honeywell one.
Google security suppliers and you will get a good selection.
As far as I know we cannot give direct links to suppliers in the rules here.

joe-90 · 7 Nov 2010

You can if you don't own it.

mryoung · 7 Nov 2010

Your problem sounds more environmental, sun hitting the detector or cold/warm drafts, even an insect inside the pyro chamber.

To be 100% sure, you need the services of an alarm company to test.

Would recommend changing to quads or dualtecs if the problem is environmental.

Alarm · 7 Nov 2010

In that case www.securitywarehouse.co.uk

Alarm · 7 Nov 2010

mryoung said:
Your problem sounds more environmental, sun hitting the detector or cold/warm drafts, even an insect inside the pyro chamber.

To be 100% sure, you need the services of an alarm company to test.

Would recommend changing to quads or dualtecs if the problem is environmental.

Why I asked the time of activations, seen this before in winter with a low sun.

mryoung · 7 Nov 2010

Alarm said:
mryoung said:

Your problem sounds more environmental, sun hitting the detector or cold/warm drafts, even an insect inside the pyro chamber.

To be 100% sure, you need the services of an alarm company to test.

Would recommend changing to quads or dualtecs if the problem is environmental.

Click to expand...

Why I asked the time of activations, seen this before in winter with a low sun.

Me slow typer

Alarm · 7 Nov 2010

yaleguy3 · 7 Nov 2010

Does the dining table have a glass top?
This might be reflecting the light and focussing it more on the pir.
You could move the pir to a corner facing 'into' the room.

I once had the local council call me out to an alarm I had installed because it kept going off every half an hour or so.

Turns out two young ladies who share the house had gone on holiday and left their hair straighteners plugged in creating a wave of warm air that kept switching on and off with the thermostat. I was able to disable their alarm without entering the property so goodness knows what their electricity bill would have been when they returned.

Alarm · 7 Nov 2010

yaleguy3 said:
I was able to disable their alarm without entering the property

OUCH TMI

Know how you did it too.

peteuk · 7 Nov 2010

Thanks to all for the quick replies so far

I have unintentionally given you the wrong idea I think.
The alarm has never gone off during the day - that we know of. Our neighbour says it has been the early hours of the morning, and when we have been in the house that's when it goes off too.
i.e. the heating is off and it's dark. Therefore the sun and it's possible reflections are not likely to be the culprit.
The dining table is solid wood and at night the vertical blinds are closed (all the time when on holiday)

The PIR is hard wired. I've had a quick look and cannot see a makers name (but I haven't tried to get into it). Iassume it is just a movement sensor, nothing particularly fancy.
Could it still be spiders?
I think I might just go for replacing it to be sure.

But I'm a DIY novice and know nothing about alarms. Can I just disconnect and reconnect.
Do I have to do anything other than switching the power off / on before / after swapping the PIR out?

Thanks again,

Pete

Pete

joe-90 · 7 Nov 2010

You've not got to short out the positive 12v supply or you'll blow a fuse in the control box.

mryoung · 7 Nov 2010

Ok so you could have cable/device issues. still think you need an engineer imo.

Any good with a meter?

No point swapping out things if its not the problem.

Edit:- just to clarify, is the system set or unset when it alarms.

Any system logs. ?

what indications a present after an alarm ie alarm, tamper, fault?

mryoung · 7 Nov 2010

joe-90 said:
You've not got to short out the positive 12v supply or you'll blow a fuse in the control box.

Sorry joe, i dont understand that. wrong post perhaps?

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Too many false alarms - please help

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