Thats a bit to cryptic for mr eng

Can you elaborate

I have also edited my previous post

Thats a bit to cryptic for mr eng 

Can you elaborate 

I have also edited my previous post

38588[/snapback]

if you have a pir facing the door,you have to watch out for the postie posting the letters at 100 mph into the hallway which can cause false alarms....

Thats a bit to cryptic for mr eng 

Can you elaborate 

I have also edited my previous post

38588[/snapback]

It is possible that when Postman Pat chucks his wad through the box it can trigger the PIR so dont point it at the door. Point it back into the hallway.

Edited January 29, 200521 yr by ian.cant

OK thanks, but dont they look for a heat signature as well as movement.

OK thanks, but dont they look for a heat signature as well as movement.

38594[/snapback]

that depends if its recorded mail..

OK thanks, but dont they look for a heat signature as well as movement.

38594[/snapback]

Nice one Gaz!

How a PIR works isnt the way your thinking. It see's IR energy and uses that as a reference, then if anything changes rapidly using its processors it decides if its big enough a change of reference and acts accordingly.

So Imagine your nice warm floor and suddenly theres a big wet cold envelope on it. Depending on the quality of your PIR and the sensetivety set up will depend on wether you get false alarms or not. Plus a bit of luck and the weather and ............

OK thanks so it can trigger from a rapid reduction in temperature as well as an increase, learn something every day.

OK thanks so it can trigger from a rapid reduction in temperature as well as an increase, learn something every day.

38606[/snapback]

Which is why when on a cloudy but sunny day, when the sun pops from behind a clound and creates a hot spot on a floor it can trigger a PIR. Also if a spider walks across the sensor it will trigger because it see's a major change in its reference picture.

Thanks for all your help Ian (and everyone else) I really appreciate it. I am looking at PIR's from TLC. Wonder if you could make some reccomendations.

360 deg ceiling PIR for the garage. Either of these any good. We do have a Chincilla in the garage in a cage, could this possibly cause false alarms with these PIR's.

http://www.tlc-direct.co.uk/Main_Index/Ala...cial/index.html

Then I need one for the hallway, one for the kitchen and one each for the Living room, Dining room and study. Not really sure what I should be looking for out of these ones.

Kitchen ?

http://www.tlc-direct.co.uk/Main_Index/Ala...arsh/index.html

Should I be looking at standard or dual tech for the rest ?

http://www.tlc-direct.co.uk/Main_Index/Ala...larm/index.html

http://www.tlc-direct.co.uk/Main_Index/Ala...Tech/index.html

Edited January 29, 200521 yr by Chewie