PIR sensor triggered by boiler steam plume....

mmm forgot abt this until last couple of days....
new boiler exhaust sited under a well-positioned PIR for (seperate, distantly mounted) outside lights.
When the boiler's burning and outside light level is low (i.e. all winter!) the steam plume/exhaust triggers the PIR and all the outside lights come on like a f-in Xmas tree....
Now that particular PIR sensor's wiring goes through the boiler room/ area -
What would it take to dream up some sort of "interlock" to temporarily switch off/disable that PIR when the boiler is firing...or is moving the PIR from it's favoured location the only way?
NB there is another PIR on the same circuit and having that and the lights still operational would be preferred
TIA cheers JimK
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JimK submitted this idea :

That would not be too difficult to accomplish, but it would not really help....
Most PIR's when they are first powered up, will turn the light on until they have settled back down.
The easy way, if it can be done is to mask the sensor with a bit of black tape so it can't 'see' the plume.
--
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Harry (M1BYT) (L)
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On Oct 23, 6:45 pm, Harry Bloomfield

I suspect that masking it enough to escape the plume would mean it may as well be removed, it's above and looking down and partially across the plume....
Is there any way to interrupt the switched live (or equiv) of the PIR when the boiler is firing - so whilst PIR still powered up (and so avoiding the startup prob) it's "false" triggers would not actually switch any lights on?
Ta JimK
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On 23 Oct, 19:05, JimK wrote:

Yes. Wire the coil of a relay to the 'call for heat' terminal of the boiler, and its contacts to interrupt the PIR output.
Owain
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ah sounds promising - can you point me to a likely looking relay somewhere please and any tips/notes on installation would be gratefully appreciated.
cheers JimK
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wrote:

At an electrical level Owain is right but I think you might hit problems with the PIR detecting the residual hot air movement after the boiler has finished firing. Remember that the PIR detects Infra Red pattern changes and to it the hot air from your boiler will look like movement.
Lot of places sell lots of suitable relays. Maplin are good for one-off DIY stuff. Look for a relay which plugs into a base just in case you ever need to replace it. You need a 230V coil SPST (single pole, single throw) with contacts rated plenty high enough for your lamp. Ideally 5A contacts would be nice as they would then be protected by the lighting circuit protection. I'd also buy a box to put it in and personally I'd mount it all on a bit of stripboard (vero) along with some screw terminals. If you do use vero you need to remove every second strip of copper by heating it and peeling it away as the inter-copper gap isn't really spec'd for mains. Consider also that your boiler circuit and your light circuit really should be kept separate, including the N.
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Look on Ebay for a contactor, eg, Square-D 25A 2-pole 5. Then stick it in a DIN enclosure. From the OP questions, playing around with veroboard & mains could get "interesting" :-)
Far simpler to move the PIR, or put the PIR on a local/spur/CU-DIN- rail timer, or fit a time-limited dusk-to-dawn photocell switch with fluorescent lighting in place of what sounds like 150-300-500W halogen "christmas tree".
The police supposedly say a photocell light is more effective than PIR, depends on your neighbours re whether a constant low level night light would make them moan... the extra's for the original Dawn Of The Dead around here.
Our neighbour blamed me for fitting interior wall lights which shone into her bedroom. Her bedroom is around the side; the wall light is far above the window so creates a 60W light-fall which goes downwards obstructed by a roller blind & obscured glass; her hall window is 9ft above ours and 20ft away so way above the light-fall path; the interior wall light is original and about 57yrs old; the sodium street light outside her driveway on the other hand... (sigh :-)
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indeed :>)) vero board etc would involve lots more guidance from you guys :>) as it is you'll have to hold my hand a bit on the practical aspects of contactor - I am confident with domestic wiring circuits, principles, practices etc but this is a (interesting) new avenue to me...
e.g. how do i interrupt the PIR switched live output with a normally open contactor?

nah don't fancy the "on all night" thing, if they are gonna have a go they can bring their own torch (and trigger the xmas tree! as long as the boiler's not on where that PIR is (etc...))
thanks JimK
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wrote:

Well the first practical aspect is that you need a normally closed contactor ("contactor" is really just another name for relay) not a normally open one.
You probably already know this but I'll cover it anyway... A contractor or relay is a switch which is turned on or off by a control current through it's coil. You're going to use a switch which is a simple single-pole (ie. one circuit), single-throw (ie. it just opens and closes), this is abbreviated to SPST. The control coil will be 230V and when a relay is controlled by 230V it often gets called a contactor.
You need to take a LN pair of wires from your boiler "calling for heat" input, (that is the switched live wire which goes live when the boiler is being told to fire up and an associated N) and connect these to the coil of the contactor. The "normally closed" bit in the contactor description says that the switch side of it is closed when the coil is de-energised and open when there's current through the coil so when the boiler is being told to fire up the switch will be open and your lights will be off and when the boiler is turned off there won't be any current through the coil so the switch will be closed.
You need to cut (break into) the switched live (only) between the PIR and the light and connect the cut ends to the switch outputs of the contactor. You need to break the output from the PIR rather than the input to it because of the tendency of PIRs to switch on when first powered up.
That's it really, easy. In fact the hardest bit will probably be the physical arrangements for getting the wires to the right place. If you can't find a suitable NC contactor it's perfectly possible to use a SPDT (the D means double or dual), also called a "changeover", and only wire to two of the three switch terminals. If you do that the switched live from the PIR goes to one of the output terminals and the wire to the light goes to the common - it's a tiny bit safer that way.
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JimK wrote:

Obviously not!
Moving it is the best long term solution - Owain's solution will work but what's the use of a PIR that only works half the time?...
--
Scott

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my boiler's not on half the night - off by 9pm plus I'm a yorkshireman - where TF do you live then?
Can we presume the Northern Lights illuminate your drive?
Cheers JimK
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JimK wrote:

Nine O'Clock or not, it gets dark in Yorkshire at 4.00p.m. in the middle of winter. If your heating system is designed, set-up and maintained for maximum efficiency, then it should be running with "long-burns", which means that, as Scott quite rightly pointed out, your PIR will regularly be out of action for minutes at a time over a period of up to five hours a night (and that's not allowing for a similar situation in the early morning if your boiler comes on before it gets light).
I would have thought that re-thinking the location of your PIR is a much more sensible option. In fact, the first thing I would do is replace the PIR - I wouldn't actually expect it to go off under these circumstances.
TLC Direct have a wide choice of Mains PIRs:
http://preview.tinyurl.com/yz94lbo
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Dave Osborne wrote:

I've got one on the drive that detects the warm body of a car engine arriving and then, if you wait for the light to go off again, will be triggered by the warm air let out by opening the door.
--
Scott

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Scott M wrote:

Ours comes on by the heat of the car engine as well as it happens.
I would, none the less, and depending on how much of a pain it would be to re-do the cables, be thinking about replacing the PIR in-situ and if that doesn't cure it, then move the existing/new PIR so it is not affected by the boiler.
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Since OP lacks the electrical skills, refit the PIR in a new position with new cable run to it.
If the cable is run on an outside wall use TLC FP200 (white) or HO5/ H07 rubber cable of 1.0mm (black). If the cable enters from the rear, use a IPx4 rated junction box, gland & run cable to the new position.
Disabling the PIR for a time is just pointless.
Relocate it as necessary, simple maintenance in view of spurious performance due to unexpected interaction with boiler exhaust plume, write out your own MWC.
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NB:- OP more than happy to expand knowledge based on that profered - hence query in 1st place :>))
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you assume the boiler is on from 4pm and that it's the only heat source.... remember there is more than PIR...

but until I explore the other options courtesy of this NG and it's contributors I won't be able to decide will I?
PIRs not responding to steam and exhaust fumes from a boiler - how's that work then?
JimK
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JimK wrote:

Soz, should have put a smiley on the first bit. South coast and also, no heat after 9pm, but as Dave says it's dark from 4pm by the solstice.
--
Scott

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