Are these Pyronix PIR’s really this unsophisticated?

[Jupiter01]

I have a number of Pyronix KX15DQ 15m Digital Quad PIR Grade 2’s installed in my home on a Texecom Premier Elite system.

I’ve had a couple of false alarms recently (and have had much support from people on this forum - thanks). I’ve checked voltage, wiring, insects, etc. but discovered something much more profound today...

My lounge has two wooden doors. I wanted to check if these doors flapping around (or similar objects) could activate the PIR. I placed my camera in the room facing the PIR. I then tied a string to the door handle and stood outside the room, behind a block built wall. I learnt that this door fully closing, activated the PIR every time. I tried the same test with both doors and got the same results! I.e. no heat or human movement

This is completely contrary to what I’ve read about the workings of Quad PIR’s and I now wonder what else maybe triggering these PIR’s.

Can someone please provide their expertise as this feels very inadequate to me.

 

[sparkymarka]

What makes you think the doors are not a different temperature to the background ...and that they don’t move cooler or hotter air ...

 

[Jupiter01]

Perhaps they are?
Would you expect that to trigger the alarm? I wonder what other moving (non-human) objects could be producing a similar effect. I am longing for something much more sophisticated than this

 

[scott1980]

It's doing what all PIRs do, detecting a movement of anything with a differing infra red energy to the background between the "zones" of the PIR (created by the fresnel lense in the cover of the detector) Curtains blowing around due to windows left open, boxes falling over in warehouses, Christmas decs hanging from school classroom ceilings, a sudden cold draught, spiders crawling across the front of the detector. This is why a professional installer will always advise that all windows and doors are secure when arming the system (even if those particular doors and windows are not directly protected by the system)

Your PIR is doing what it is designed to do.

 

[AdrianUK]

If you want something that is more immune....then use a "dual-tech" sensor. These use a PIR combined with a microwave sensor & only go into alarm when both detect something.

 

[Jupiter01]

Thanks for the responses guys. Much appreciated.
Would a dual-tech sensor "definitely" behave differently under the same conditions? I ask, as I have a DT in my garage and loft. I've had a false alarm in the garage over the course of the year too. The most obvious cause appeared to be a flapping bubble wrap near the sensor. This is just what I observed in the immediate aftermath!

As a layman, I am surprised that house alarms which are hardly cutting edge given how long they have been on the market haven't developed beyond their current state. I can't be the only house owner who is after an accurate detection of an intruder without having to invest in commercial grade/exorbitantly priced systems...

I take the earlier point on how a PIR works and that the "door flapping" case is handled expectantly but is there any empathy for my point of view? Or should I just suck it up!

Thanks again.

 

[sparkymarka]

Suck it up

 

[Ian J]

My Pyronix installer put the PIR/Microwave sensors in the garage to allow for the possible greater temperature difference and draughts.

 

[sparkymarka]

Any decent installer would anyway

 

[Jupiter01]

Thanks for the responses guys.
I also have DT in the garage and loft.

Returning to the Quad PIR's and my current experiences, I don't think that replacing all of these to DT resolves my gripe either? In a different post, I've had individuals suggesting that spiders and other crawlies "could" still trigger a alarm? I genuinely, can't see how people cope with these Quad PIR's... I had two false alarms yesterday and noticed that a moth was flying in the room in question!

 

[AdrianUK]

Well, if your asking "Is there a sensor which will never ever give a false detection, guaranteed" then the answer has to be a resounding NO! You can take measures to prevent spiders etc getting inside a sensor (eg. make the cable entry hole as small as possible and/or seal it with mastic), but if a spider does crawl over the front of the senor, its probably gonna trigger it - housekeeping is the only way to deal with that.

DTs requires both the PIR & the microwave to give a yes before the detector triggers. Since these technologies rely on different principles to operate then its the best your gonna get. If you want to go to the next level you could use two DTs and configure them in a "double knock" pair on the panel - meaning that both must go into alarm within a certain time window for the system to go into alarm.

 

[Jupiter01]

Thanks @AdrianUK. That was very helpful and you set out the options very clearly.

A few questions please.
- how would a DT cope with the spider crawling across the sensor?
- with “double knock” (not considering yet!) can it run off a single cable to the panel? I only have one cable coming to each zone currently and it wouldn’t be easy to bring another cable to each zone. It also feels impractical to have two sensors everywhere...
- how are others coping with Quad PIR’s as despite the housekeeping measures, it’s very difficult to keep the crawlers at bay and especially this time of the year!

As an update, I’ve used my paranoia to go through each PIR today and double check cables, seal the holes and terminate unused cables into these connectors.

 

[Jupiter01]

Hi, can someone help me with the above please? Thanks again

 

[bernardgreen]

how would a DT cope with the spider crawling across the sensor?

In theory and good design the microwave sensor would ignore echos from objects close to the sensor. So the spider would not ( should not ) trigger the alarm. BUT by being on the sensor the spider could prevent the micro-wave from reaching an intruder.

Break beam detectors are less prone to false alarms and if well placed will reliably detect intruders. They just cost more.

 

[steveo44]

As a layman, I am surprised that house alarms which are hardly cutting edge given how long they have been on the market haven't developed beyond their current state. I can't be the only house owner who is after an accurate detection of an intruder without having to invest in commercial grade/exorbitantly priced systems...


Thanks again.

What do you expect for a tenner!

I’d fit a Pyronix TMD set up as tri-mode.