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#1
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Alarm question - PIRs, window contacts or optical boundary?
When I re-furb'ed my last house I fitted window switches to all
accessible windows and external doors, so didn't need to bother with PIRs. The current house already has a "professionally installed" alarm with PIRs and door contacts, but no window contacts. I was going to replace the PIRs with (a large quantity of) window switches but am having second thoughts because of the unsightly wiring. SWMBO is concerned about staying with the PIRs because, if we set the downstairs ones at night, of what happens if someone goes down for a drink or a wander around in the night. How does everyone else cope with this? I'm wondering whether it's viable to set-up an external boundary around the house using infra red or laser beams/detectors (above animal height). Has anyone used this technique? |
#2
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Alarm question - PIRs, window contacts or optical boundary?
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#4
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Alarm question - PIRs, window contacts or optical boundary?
On 27/09/2017 15:10, Bill Wright wrote:
On 27/09/2017 14:57, wrote: When I re-furb'ed my last house I fitted window switches to all accessible windows and external doors, so didn't need to bother with PIRs. The current house already has a "professionally installed" alarm with PIRs and door contacts, but no window contacts. I was going to replace the PIRs with (a large quantity of) window switches but am having second thoughts because of the unsightly wiring. SWMBO is concerned about staying with the PIRs because, if we set the downstairs ones at night, of what happens if someone goes down for a drink or a wander around in the night. How does everyone else cope with this? I'm wondering whether it's viable to set-up an external boundary around the house using infra red or laser beams/detectors (above animal height). Has anyone used this technique? Personally I'd forget window contacts. They do false alarm if there's a gust of wind or a bird hits one. The actual units (Vipers etc) are prone to damp. The wiring is very labour intensive unless it's done at first fix stage in a new building. It is possible to make it invisible but it's hard work. PIRs are generally OK as long as they are wired (not wireless) and are dual tech (microwave as well as IR). I have external beams to protect the parking area. They're pretty good for that purpose, but not for protecting the house when you aren't there because of perfectly innocent callers (unless they send a silent alarm to your phone and/or run the CCTV). The type with two independent parallel beams are best. With all alarms remember that one false alarm means that everyone within earshot will ignore your alarm for the next ten years. Bill I was thinking of using sealed reed switches (which is what I used in the previous house) - how do they get affected by damp? The existing PIRs are wired, but aren't "animal proof" so I need to either replace them or change to switches. The problem is still what happens when people wander about in the night when the alarm is set. |
#5
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Alarm question - PIRs, window contacts or optical boundary?
On 27/09/2017 16:59, wrote:
On 27/09/2017 15:10, Bill Wright wrote: On 27/09/2017 14:57, wrote: When I re-furb'ed my last house I fitted window switches to all accessible windows and external doors, so didn't need to bother with PIRs. The current house already has a "professionally installed" alarm with PIRs and door contacts, but no window contacts. I was going to replace the PIRs with (a large quantity of) window switches but am having second thoughts because of the unsightly wiring. It is a lot of work for not much gain. Burglars tend to go for empty houses anyway and the PIR trigger will go off soon enough to deter them. My dad had external perimeter reed switches fairly neatly done but it was a lot of work and wiring to be hidden. I just have window locks. SWMBO is concerned about staying with the PIRs because, if we set the downstairs ones at night, of what happens if someone goes down for a drink or a wander around in the night. How does everyone else cope with this? I'm wondering whether it's viable to set-up an external boundary around the house using infra red or laser beams/detectors (above animal height). Has anyone used this technique? Personally I'd forget window contacts. They do false alarm if there's a gust of wind or a bird hits one. The actual units (Vipers etc) are prone to damp. The wiring is very labour intensive unless it's done at first fix stage in a new building. It is possible to make it invisible but it's hard work. PIRs are generally OK as long as they are wired (not wireless) and are dual tech (microwave as well as IR). I have external beams to protect the parking area. They're pretty good for that purpose, but not for protecting the house when you aren't there because of perfectly innocent callers (unless they send a silent alarm to your phone and/or run the CCTV). The type with two independent parallel beams are best. With all alarms remember that one false alarm means that everyone within earshot will ignore your alarm for the next ten years. Bill I was thinking of using sealed reed switches (which is what I used in the previous house) - how do they get affected by damp? They don't but they do sometimes end up stuck closed so that they don't actually trigger by opening when they should. The panic alarm button on my system is a magnet and reed switch and failed this way. The existing PIRs are wired, but aren't "animal proof" so I need to either replace them or change to switches. The problem is still what happens when people wander about in the night when the alarm is set. You mask out all the zones that you are likely to walk through for the night setting (and/or remember to switch it off when you get up). -- Regards, Martin Brown |
#6
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Alarm question - PIRs, window contacts or optical boundary?
On 27/09/2017 16:02, Brian Gaff wrote:
What about fog? Brian Good point (snow too) but the problem can be minimised by choice of power (I'm aware of the laser regs) and distance, and the gate passage detectors seem to work OK in practice. There's an interesting article he http://www.ece.mcmaster.ca/~hranilov.../spie2000b.pdf, although it's only slightly relevant. |
#7
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Alarm question - PIRs, window contacts or optical boundary?
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#8
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Alarm question - PIRs, window contacts or optical boundary?
On 27/09/2017 17:29, Huge wrote:
On 2017-09-27, wrote: When I re-furb'ed my last house I fitted window switches to all accessible windows and external doors, so didn't need to bother with PIRs. The current house already has a "professionally installed" alarm with PIRs and door contacts, but no window contacts. I was going to replace the PIRs with (a large quantity of) window switches but am having second thoughts because of the unsightly wiring. SWMBO is concerned about staying with the PIRs because, if we set the downstairs ones at night, of what happens if someone goes down for a drink or a wander around in the night. How does everyone else cope with this? This has the same answer as the old joke about the man who goes to his Doctor and says "It hurts when I do this". Don't do that, then. :-) I would like to control what some of my guests do in the night but I might get into trouble if I tried |
#9
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Alarm question - PIRs, window contacts or optical boundary?
On 27/09/2017 17:24, Andy Burns wrote:
wrote: I'm wondering whether it's viable to set-up an external boundary around the house using infra red or laser beams/detectors (above animal height). Has anyone used this technique? You can get dual-beam detectors, which are supposedly spaced so that animals/birds/trees in the wind etc will only break one beam, but humans will break both and set them off, then use corner reflectors to bounce the beam round your perimeter up to 100m, they use pulsed beams presumably for anti-tamper. Thanks, I'll look around. It reminds me of that old heist film where the actress (supposedly) had to learn to gymnastically gyrate around a room full of IR beams - Entrapment, I think. |
#10
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Alarm question - PIRs, window contacts or optical boundary?
On 27/09/2017 17:30, Huge wrote:
On 2017-09-27, wrote: [40 lines snipped] The existing PIRs are wired, but aren't "animal proof" None of them are. Some claim to only respond to the thermal image of an object over 30kg - that's a pretty large dog or moggy! |
#11
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Alarm question - PIRs, window contacts or optical boundary?
Huge wrote:
nomail wrote: Some claim to only respond to the thermal image of an object over 30kg - that's a pretty large dog or moggy! We have one of those in the garage. A bat set it off. We had it "adjusted". A bat set it off. Bats have the ability to get closer to the PIR than a dog down on the ground, presumably they're quite warm when not roosting? |
#12
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Alarm question - PIRs, window contacts or optical boundary?
On Wed, 27 Sep 2017 18:48:41 +0100, nomail wrote:
On 27/09/2017 17:30, Huge wrote: On 2017-09-27, wrote: [40 lines snipped] The existing PIRs are wired, but aren't "animal proof" None of them are. Some claim to only respond to the thermal image of an object over 30kg - that's a pretty large dog or moggy! Newfoundland. -- My posts are my copyright and if @diy_forums or Home Owners' Hub wish to copy them they can pay me £1 a message. Use the BIG mirror service in the UK: http://www.mirrorservice.org *lightning surge protection* - a w_tom conductor |
#13
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Alarm question - PIRs, window contacts or optical boundary?
Wrote in message:
When I re-furb'ed my last house I fitted window switches to all accessible windows and external doors, so didn't need to bother with PIRs. The current house already has a "professionally installed" alarm with PIRs and door contacts, but no window contacts. I was going to replace the PIRs with (a large quantity of) window switches but am having second thoughts because of the unsightly wiring. SWMBO is concerned about staying with the PIRs because, if we set the downstairs ones at night, of what happens if someone goes down for a drink or a wander around in the night. How does everyone else cope with this? I'm wondering whether it's viable to set-up an external boundary around the house using infra red or laser beams/detectors (above animal height). Has anyone used this technique? The PIR covering the route from the bottom of the stairs to the panel needs to be an entry/exit zone .. When you go downstairs, the panel bleeps to remind you to turn off the alarm before getting the midnight feast. -- ----Android NewsGroup Reader---- http://usenet.sinaapp.com/ |
#14
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Alarm question - PIRs, window contacts or optical boundary?
In article ,
Andy Burns writes: Huge wrote: nomail wrote: Some claim to only respond to the thermal image of an object over 30kg - that's a pretty large dog or moggy! We have one of those in the garage. A bat set it off. We had it "adjusted". A bat set it off. Bats have the ability to get closer to the PIR than a dog down on the ground, presumably they're quite warm when not roosting? Bats tend to fly up into corners of rooms (looking for something they can grab hold of), and that's exactly where PIR's are often mounted. -- Andrew Gabriel [email address is not usable -- followup in the newsgroup] |
#15
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Alarm question - PIRs, window contacts or optical boundary?
Andrew Gabriel wrote:
Bats tend to fly up into corners of rooms (looking for something they can grab hold of), and that's exactly where PIR's are often mounted. Maybe there's circuitry within the sensor (assuming it's not actually a combined PIR/ultrasonic one) which happens to oscillate in the bat's hearing range that they find "interesting" ... |
#16
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Alarm question - PIRs, window contacts or optical boundary?
"Bill Wright" wrote in message news On 27/09/2017 14:57, wrote: When I re-furb'ed my last house I fitted window switches to all accessible windows and external doors, so didn't need to bother with PIRs. The current house already has a "professionally installed" alarm with PIRs and door contacts, but no window contacts. I was going to replace the PIRs with (a large quantity of) window switches but am having second thoughts because of the unsightly wiring. SWMBO is concerned about staying with the PIRs because, if we set the downstairs ones at night, of what happens if someone goes down for a drink or a wander around in the night. How does everyone else cope with this? I'm wondering whether it's viable to set-up an external boundary around the house using infra red or laser beams/detectors (above animal height). Has anyone used this technique? Personally I'd forget window contacts. They do false alarm if there's a gust of wind or a bird hits one. The actual units (Vipers etc) are prone to damp. The wiring is very labour intensive unless it's done at first fix stage in a new building. It is possible to make it invisible but it's hard work. PIRs are generally OK as long as they are wired (not wireless) and are dual tech (microwave as well as IR). I have external beams to protect the parking area. They're pretty good for that purpose, but not for protecting the house when you aren't there because of perfectly innocent callers (unless they send a silent alarm to your phone and/or run the CCTV). The type with two independent parallel beams are best. With all alarms remember that one false alarm means that everyone within earshot will ignore your alarm for the next ten years. We dont do that with the neighbours alarms. We still turn out do check if its a false alarm or not, but its only me that does that at 2am etc. |
#17
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Alarm question - PIRs, window contacts or optical boundary?
On Wednesday, 27 September 2017 14:57:50 UTC+1, wrote:
When I re-furb'ed my last house I fitted window switches to all accessible windows and external doors, so didn't need to bother with PIRs. The current house already has a "professionally installed" alarm with PIRs and door contacts, but no window contacts. I was going to replace the PIRs with (a large quantity of) window switches but am having second thoughts because of the unsightly wiring. SWMBO is concerned about staying with the PIRs because, if we set the downstairs ones at night, of what happens if someone goes down for a drink or a wander around in the night. How does everyone else cope with this? I'm wondering whether it's viable to set-up an external boundary around the house using infra red or laser beams/detectors (above animal height). Has anyone used this technique? Window switches: Enamelled copper wire can be disappeared in a superficial scratch in plaster. Make sure to fit them to part of the frame where distortion & wind can't trigger them. Check the current is in range for the reed relay, they tend to fail if it's too high or too low. They don't of course detect broken glass. You can get glass break detectors too. PIR: they will sense you if you go there. Full stop. Beam break: used that long ago, very effective. Can sometimes be placed where you won't walk at night, and where any door shutting will trigger it. Make sure the detector & mirror can't ever slip out of alignment or it'll trigger. Personally I'd want to treat one detection event as a minor warning, and 2 as a person present rather than 1. NT |
#18
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Alarm question - PIRs, window contacts or optical boundary?
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#19
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Alarm question - PIRs, window contacts or optical boundary?
On 27/09/2017 17:30, Huge wrote:
On 2017-09-27, wrote: [40 lines snipped] The existing PIRs are wired, but aren't "animal proof" None of them are. It isn't possible. Bill |
#20
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Alarm question - PIRs, window contacts or optical boundary?
On 27/09/2017 18:48, wrote:
On 27/09/2017 17:30, Huge wrote: On 2017-09-27, wrote: [40 lines snipped] The existing PIRs are wired, but aren't "animal proof" None of them are. Some claim to only respond to the thermal image of an object over 30kg - that's a pretty large dog or moggy! Insensitive then to a crim in a donkey jacket and hood. Bill |
#21
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Alarm question - PIRs, window contacts or optical boundary?
"Bill Wright" wrote in message news On 27/09/2017 17:30, Huge wrote: On 2017-09-27, wrote: [40 lines snipped] The existing PIRs are wired, but aren't "animal proof" None of them are. It isn't possible. It is actually tho it wont register the baby on the floor either. |
#22
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Alarm question - PIRs, window contacts or optical boundary?
"Bill Wright" wrote in message news On 27/09/2017 18:48, wrote: On 27/09/2017 17:30, Huge wrote: On 2017-09-27, wrote: [40 lines snipped] The existing PIRs are wired, but aren't "animal proof" None of them are. Some claim to only respond to the thermal image of an object over 30kg - that's a pretty large dog or moggy! Insensitive then to a crim in a donkey jacket and hood. Nope. |
#23
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Alarm question - PIRs, window contacts or optical boundary?
In article ,
Bill Wright wrote: On 27/09/2017 17:30, Huge wrote: On 2017-09-27, wrote: [40 lines snipped] The existing PIRs are wired, but aren't "animal proof" None of them are. It isn't possible. Recentl;y I was in a "gents" which used a PIR to turn on the lighting - fine, but it only sensed you standing up. When I sat down, the light went out!! -- from KT24 in Surrey, England |
#24
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Alarm question - PIRs, window contacts or optical boundary?
On 27/09/2017 22:06, Andy Burns wrote:
Andrew Gabriel wrote: Bats tend to fly up into corners of rooms (looking for something they can grab hold of), and that's exactly where PIR's are often mounted. Maybe there's circuitry within the sensor (assuming it's not actually a combined PIR/ultrasonic one) which happens to oscillate in the bat's hearing range that they find "interesting" ... I think it is more that the bat explores all the available space in the room looking for a way out. If they ever end up on the floor then they can find it impossible to climb up again on painted skirting boards. In the wild they would climb the nearest rough piece of wood. -- Regards, Martin Brown |
#25
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Alarm question - PIRs, window contacts or optical boundary?
On 28/09/2017 04:07, Bill Wright wrote:
On 27/09/2017 18:48, wrote: On 27/09/2017 17:30, Huge wrote: On 2017-09-27, wrote: [40 lines snipped] The existing PIRs are wired, but aren't "animal proof" None of them are. Some claim to only respond to the thermal image of an object over 30kg - that's a pretty large dog or moggy! Insensitive then to a crim in a donkey jacket and hood. You can beat a PIR detector but that isn't the way. -- Regards, Martin Brown |
#26
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Alarm question - PIRs, window contacts or optical boundary?
"Martin Brown" wrote in message news On 28/09/2017 04:07, Bill Wright wrote: On 27/09/2017 18:48, wrote: On 27/09/2017 17:30, Huge wrote: On 2017-09-27, wrote: [40 lines snipped] The existing PIRs are wired, but aren't "animal proof" None of them are. Some claim to only respond to the thermal image of an object over 30kg - that's a pretty large dog or moggy! Insensitive then to a crim in a donkey jacket and hood. You can beat a PIR detector but that isn't the way. What is the way ? |
#27
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Alarm question - PIRs, window contacts or optical boundary?
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#28
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Alarm question - PIRs, window contacts or optical boundary?
On 28/09/2017 04:06, Bill Wright wrote:
On 27/09/2017 17:30, Huge wrote: On 2017-09-27, wrote: [40 lines snipped] The existing PIRs are wired, but aren't "animal proof" None of them are. It isn't possible. Bill Honeywell seem to think it is: https://www.security.honeywell.com/u...se/868366.html .... selectable up to 36kg. Another manufacturer says 30kg. |
#29
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Alarm question - PIRs, window contacts or optical boundary?
On 28/09/2017 12:01, Huge wrote:
On 2017-09-28, wrote: On 28/09/2017 04:06, Bill Wright wrote: On 27/09/2017 17:30, Huge wrote: On 2017-09-27, wrote: [40 lines snipped] The existing PIRs are wired, but aren't "animal proof" None of them are. It isn't possible. Bill Honeywell seem to think it is: They're wrong. "Is this the 5 minute argument or the full half hour?", to quote a Monty Python sketch ;-) Thanks for your opinion, but I'm happy to assume that Honeywell and other manufacturers know their products and would not make claims that could be easily demonstrated to be false, if they were. |
#30
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Alarm question - PIRs, window contacts or optical boundary?
On Thursday, 28 September 2017 16:26:02 UTC+1, wrote:
On 28/09/2017 12:01, Huge wrote: On 2017-09-28, wrote: On 28/09/2017 04:06, Bill Wright wrote: On 27/09/2017 17:30, Huge wrote: On 2017-09-27, wrote: [40 lines snipped] The existing PIRs are wired, but aren't "animal proof" None of them are. It isn't possible. Bill Honeywell seem to think it is: They're wrong. "Is this the 5 minute argument or the full half hour?", to quote a Monty Python sketch ;-) Thanks for your opinion, but I'm happy to assume that Honeywell and other manufacturers know their products and would not make claims that could be easily demonstrated to be false, if they were. now that's amusing NT |
#31
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Alarm question - PIRs, window contacts or optical boundary?
On Thursday, 28 September 2017 16:26:02 UTC+1, wrote:
On 28/09/2017 12:01, Huge wrote: On 2017-09-28, wrote: On 28/09/2017 04:06, Bill Wright wrote: On 27/09/2017 17:30, Huge wrote: On 2017-09-27, wrote: [40 lines snipped] The existing PIRs are wired, but aren't "animal proof" None of them are. It isn't possible. Bill Honeywell seem to think it is: They're wrong. "Is this the 5 minute argument or the full half hour?", to quote a Monty Python sketch ;-) Thanks for your opinion, but I'm happy to assume that Honeywell and other manufacturers know their products and would not make claims that could be easily demonstrated to be false, if they were. now that's amusing NT |
#32
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Alarm question - PIRs, window contacts or optical boundary?
In article ,
Martin Brown writes: On 27/09/2017 22:06, Andy Burns wrote: Andrew Gabriel wrote: Bats tend to fly up into corners of rooms (looking for something they can grab hold of), and that's exactly where PIR's are often mounted. Maybe there's circuitry within the sensor (assuming it's not actually a combined PIR/ultrasonic one) which happens to oscillate in the bat's hearing range that they find "interesting" ... I think it is more that the bat explores all the available space in the room looking for a way out. If they ever end up on the floor then they can find it impossible to climb up again on painted skirting boards. In the wild they would climb the nearest rough piece of wood. Many years ago in a previous house, I woke up in the middle of the night. Not sure what woke me, but there was enough residual light in the room for me to make out several things dive-bombing me in bed. Turned the light on, and they were bats, repeatedly swooping down in the middle of the room as they flew between opposite corners of the room, trying but failing to find something they could grab hold of in the corners near ceiling level. I was thinking if I sit up, I'm going to get hit, but then I thought they have good echo location for that, and sure enough they went around me. Wasn't much I could do to catch them, but they eventaully ran out of energy and dropped to the floor. Hadn't occured to me they can't take off from the floor, but I lifted the outside at that point and put them in a tree. They had come in where some large holes were left in the ceiling through to the loft the previous day. I fixed up the holes next day. I was often in that loft and it was all nice and clean with new insulation, and I never saw any sign of them in the loft, but presumably they were there somewhere. -- Andrew Gabriel [email address is not usable -- followup in the newsgroup] |
#33
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Alarm question - PIRs, window contacts or optical boundary?
wrote in message ... On Thursday, 28 September 2017 16:26:02 UTC+1, wrote: On 28/09/2017 12:01, Huge wrote: On 2017-09-28, wrote: On 28/09/2017 04:06, Bill Wright wrote: On 27/09/2017 17:30, Huge wrote: On 2017-09-27, wrote: [40 lines snipped] The existing PIRs are wired, but aren't "animal proof" None of them are. It isn't possible. Bill Honeywell seem to think it is: They're wrong. "Is this the 5 minute argument or the full half hour?", to quote a Monty Python sketch ;-) Thanks for your opinion, but I'm happy to assume that Honeywell and other manufacturers know their products and would not make claims that could be easily demonstrated to be false, if they were. now that's amusing Not with a claim thats so trivial to prove as that one. If their PIRs cant distinguish between pets and humans of more than crawling baby size, there would be hordes sayin that on amazon alone, and there arent. QED, their PIRs will do what they say. |
#34
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Alarm question - PIRs, window contacts or optical boundary?
In article ,
Bill Wright wrote: Personally I'd forget window contacts. They do false alarm if there's a gust of wind or a bird hits one. Eh? If you're talking reed switches you'd need a pretty terrible fitting window before wind would break the circuit. And if things like that are flapping around in the wind, a PIR might well trigger too. -- *If vegetable oil comes from vegetables, where does baby oil come from? * Dave Plowman London SW To e-mail, change noise into sound. |
#35
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Alarm question - PIRs, window contacts or optical boundary?
On Thursday, 28 September 2017 22:01:28 UTC+1, Rod Speed wrote:
tabbypurr wrote in message ... On Thursday, 28 September 2017 16:26:02 UTC+1, wrote: On 28/09/2017 12:01, Huge wrote: On 2017-09-28, wrote: On 28/09/2017 04:06, Bill Wright wrote: On 27/09/2017 17:30, Huge wrote: On 2017-09-27, wrote: [40 lines snipped] The existing PIRs are wired, but aren't "animal proof" None of them are. It isn't possible. Bill Honeywell seem to think it is: They're wrong. "Is this the 5 minute argument or the full half hour?", to quote a Monty Python sketch ;-) Thanks for your opinion, but I'm happy to assume that Honeywell and other manufacturers know their products and would not make claims that could be easily demonstrated to be false, if they were. now that's amusing Not with a claim thats so trivial to prove as that one. If their PIRs cant distinguish between pets and humans of more than crawling baby size, there would be hordes sayin that on amazon alone, and there arent. QED, their PIRs will do what they say. Promotional claims usually feature a list of conditions, which often don't fit typical use, often use weasel words and phrases like 'upto' or 'in tests' which the mfr designed specifically to avoid the issues etc. Fools take such claims at face value. Re PIRs specifically, it's not possible to design a PIR detector that won't detect a bat landing on it. Yes you can tell the difference between a cat and a human at say 5 yards, but when the human is 15 yards away and the cat 1 yard, it can't. It's basic physics. NT |
#36
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Alarm question - PIRs, window contacts or optical boundary?
wrote in message ... On Thursday, 28 September 2017 22:01:28 UTC+1, Rod Speed wrote: tabbypurr wrote in message ... On Thursday, 28 September 2017 16:26:02 UTC+1, wrote: On 28/09/2017 12:01, Huge wrote: On 2017-09-28, wrote: On 28/09/2017 04:06, Bill Wright wrote: On 27/09/2017 17:30, Huge wrote: On 2017-09-27, wrote: [40 lines snipped] The existing PIRs are wired, but aren't "animal proof" None of them are. It isn't possible. Bill Honeywell seem to think it is: They're wrong. "Is this the 5 minute argument or the full half hour?", to quote a Monty Python sketch ;-) Thanks for your opinion, but I'm happy to assume that Honeywell and other manufacturers know their products and would not make claims that could be easily demonstrated to be false, if they were. now that's amusing Not with a claim thats so trivial to prove as that one. If their PIRs cant distinguish between pets and humans of more than crawling baby size, there would be hordes sayin that on amazon alone, and there arent. QED, their PIRs will do what they say. Promotional claims usually feature a list of conditions, Yes, and those often say that you can dial up the weight of the animal above which it will register the detection of. which often don't fit typical use, These clearly do. often use weasel words and phrases like 'upto' Nothing weasel about that in this case. or 'in tests' which the mfr designed specifically to avoid the issues etc. Fools take such claims at face value. And those who get one of those animal insensitive PIRs which allow you to specify the weight of the animal, who find that the description turns out to be a lie and who have bought one on amazon are free to say its a lie and will do. Re PIRs specifically, it's not possible to design a PIR detector that won't detect a bat landing on it. Yes you can tell the difference between a cat and a human at say 5 yards, but when the human is 15 yards away and the cat 1 yard, it can't. BULL****. It's basic physics. Even sillier than you usually manage with the dual mode PIRs. |
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Alarm question - PIRs, window contacts or optical boundary?
On Friday, 29 September 2017 04:12:50 UTC+1, Rod Speed wrote:
tabbypurr wrote in message Re PIRs specifically, it's not possible to design a PIR detector that won't detect a bat landing on it. Yes you can tell the difference between a cat and a human at say 5 yards, but when the human is 15 yards away and the cat 1 yard, it can't. BULL****. It's basic physics. Even sillier than you usually manage with the dual mode PIRs. with respect I was discussing PIRs not dual technology detectors |
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Alarm question - PIRs, window contacts or optical boundary?
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Alarm question - PIRs, window contacts or optical boundary?
On 29/09/2017 00:05, Dave Plowman (News) wrote:
In article , Bill Wright wrote: Personally I'd forget window contacts. They do false alarm if there's a gust of wind or a bird hits one. Eh? If you're talking reed switches you'd need a pretty terrible fitting window before wind would break the circuit. And if things like that are flapping around in the wind, a PIR might well trigger too. Course I'm not talking about simple reed switches. I'm talking about break glass detectors. Bill |
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Alarm question - PIRs, window contacts or optical boundary?
wrote
Rod Speed wrote tabbypurr wrote in message Re PIRs specifically, it's not possible to design a PIR detector that won't detect a bat landing on it. Yes you can tell the difference between a cat and a human at say 5 yards, but when the human is 15 yards away and the cat 1 yard, it can't. BULL****. It's basic physics. Even sillier than you usually manage with the dual mode PIRs. with respect I was discussing PIRs not dual technology detectors The Honeywell PIRs being discussed that allow you to dial in the weight of the pet that they will ignore are in fact dual technology detectors. |
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