In article , Jon Weaver
writes
My Conservatory is finally finished (Which I am sure you will be glad
to hear means no more questions)

I am thinking of fitting a PIR sensor off of my house alarm, just to
give me that extra bit of protection.

Is a PIR a good idea in a construction like this.

As the temperature will fluctuate, could this trigger the PIR.

But more imporantly, because its almost entirely glass, can a PIR "see
through" the glass, to anything moving outside?

I haven't tried it, but would have thought that you would get lots of
false alarms due to sunlight & temperature changes. PIR's always say
"don't point at a window", well you can't really avoid that in a
conservatory.

You can get "dual technology" detectors which combine doppler radar &
PIR, that might work.

--
Tim Mitchell

Tim Mitchell wrote:
Is a PIR a good idea in a construction like this.

As the temperature will fluctuate, could this trigger the PIR.

But more imporantly, because its almost entirely glass, can a PIR
"see through" the glass, to anything moving outside?

I haven't tried it, but would have thought that you would get lots of
false alarms due to sunlight & temperature changes. PIR's always say
"don't point at a window", well you can't really avoid that in a
conservatory.

You can get "dual technology" detectors which combine doppler radar &
PIR, that might work.

Our shops used to suffer false detection due to large plate glass windows
and thermal effects, but we never pointed PIRs at the plate glass they were
usually mounted above.

In your case a 'break glass detector' coupled to door contacts may be the
way to go.
I don't mean the silver tape you see applied to large commercial windows;
the BGD is more of an audio device. The combination of an impact & the
breakage will trigger it, a single sensor will cover a 16m2 area easily.
Sadly alarms didn't seem to bother the ram raiders we were prone to.

Toby.

"Jon Weaver" wrote in message
om...
My Conservatory is finally finished (Which I am sure you will be glad
to hear means no more questions)

I am thinking of fitting a PIR sensor off of my house alarm, just to
give me that extra bit of protection.

Is a PIR a good idea in a construction like this.

As the temperature will fluctuate, could this trigger the PIR.

But more imporantly, because its almost entirely glass, can a PIR "see
through" the glass, to anything moving outside?

You would have to fit a dual-tech microwave passive infra-red if it's in a
situation like that. A dual-tech must have a moving heat source to be
activated properly and is designed for such an environment such as
conservatories and areas where wide temperature and lighting variation
occur. There are many different styles and sizes on the market now, so you
can pick one that will suit your surroundings.

Here's an example of just one from Pyronix:

http://tinyurl.com/n49n

A web search for dual-tech PIR will bring up many more.


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"Jon Weaver" wrote in message
om...
My Conservatory is finally finished (Which I am sure you will be glad
to hear means no more questions)

I am thinking of fitting a PIR sensor off of my house alarm, just to
give me that extra bit of protection.

Is a PIR a good idea in a construction like this.

As the temperature will fluctuate, could this trigger the PIR.

But more imporantly, because its almost entirely glass, can a PIR "see
through" the glass, to anything moving outside?

You can get PIR sensors specifically designed for harsh environments like
conservatories, have a look at www.tlc-direct.co.uk

Jon Weaver wrote:
My Conservatory is finally finished (Which I am sure you will be glad
to hear means no more questions)

I am thinking of fitting a PIR sensor off of my house alarm, just to
give me that extra bit of protection.

Is a PIR a good idea in a construction like this.

As the temperature will fluctuate, could this trigger the PIR.

But more imporantly, because its almost entirely glass, can a PIR "see
through" the glass, to anything moving outside?


I Have had a dual-tec pir sensor in my conservatory for three years
now and never had a false alarm.

Paul.