PIR's

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r.bartlett

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Hi guy's

Do PIR's 'see' through windows??

I'm looking to fit one PIR looking towards the conservatory doors at a distance of 3 metres but wondered if someone passed by would the PIR sense movement and alarm?

Cheers

Richard
 
NO.

PIR stand for Passive Infra Red (note the Passive bit)
They see the movemrnt of heat, you and I see light

a pir can not see through glass

never put a pir in a conservatory, if its in the room adjoining the conservatory , put it on the same wall as the doors looking into the room
 
breezer said:
NO.

a pir can not see through glass
Click to expand...

But it can sense a moving heat source through glass. As proven by the sensors in an estate of new house where cars slowly passing houses trip the sensors that are placed on the wall of the living room opposite the window.

The alarms are either never used or have had the sensors re-sited.
 
bernardgreen said:
breezer said:
NO.

a pir can not see through glass
Click to expand...

But it can sense a moving heat source through glass. As proven by the sensors in an estate of new house where cars slowly passing houses trip the sensors that are placed on the wall of the living room opposite the window.

The alarms are either never used or have had the sensors re-sited.
Click to expand...

nope, they can not see through glass. that is 100% true. PIR's can NOT see through glass

how ever was this at night?
 
It depends on the Sensitivity, the heat source and the positioning of the PIR, just tried an experiment with a spare PIR from my alarm system I left the PIR in the porch (only place that has single glazed glass) and went outside into the front garden ( the things we do to try to help others get answers, hate to think what the neighbours must think :lol: ) and I can get the walk test LED to light as I wave my hand passed the window.
So some heat must be being detected through the glass?
 
nope, try again.

Pirs can not see through glass, no matter how elcheapo the pir is.

are you sure it was a pir and not a duel tech?

see my new post
 
If PIRs saw through glass - the window cleaner would be a thing of the past.
 
joe 90 is 100% right, RF Lighting is 50% right.


a dueltech is, by its name dueltechnology.

one half is a pir which can not see through glass, the other is a microwave which can see through glass. But for an activation both technologies need to activate at the same time, so if one sees something but the other doesnt, the detector does not activate.
 
breezer said:
nope, try again.

Pirs can not see through glass, no matter how elcheapo the pir is.

are you sure it was a pir and not a duel tech?

see my new post
Click to expand...
definitely a PIR not microwave.read your new post but it didn't mention anything more than I already knew about them, I've had experience with PIR's from the early days when they gave false readings if you flinched at them :wink: to the sophisticated versions like the one I used in my experiment that has to sense movement across adjacent zones within a time period before it responds to eliminate false readings.
All I can say is it does seem to sense through glass so there must be transmission of heat through it and the movement of my hand is being detected. Just to clarify my hand movement was deliberate in a horizontal plane so as to trigger multiple zones within the PIR. The limitations of my experiment was the size of the test area I cannot measure at 3 metres like the OP was talking about my experiment was utilizing the width of my porch (approx 5')
 
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