Alarm advice - PIRs vs contact/inertia sensors

gizmo555

I've just got a quote from Eircom Phonewatch for a wireless system which includes a large number of contact/inertia sensors on all ground floor windows. There are just two PIRs - in the hall and upstairs on the landing

In my last house, I had a wireless system which had no sensors on windows at all - just the external doors. Instead, there were more PIRs.

The rationale of the installer there was that window sensors are prone to false alarms in windy weather and burglars have been known to repeatedly activate the alarm by rattling windows. When the exasperated homeowner deactivates the alarm after a couple of days, they strike.

I believe with the new Garda requirements for monitored alarms, PIRs can also be useful for verifying an activation, if they detect someone moving around the house.

Has anyone - especially someone with experience in the trade - got any advice/views which type of setup is most effective?

Thanks!

Stoner

gizmo,

IMO a combination of the two is best, keeping perimeter protection is a good thing and even better when layered with PIRs. Personally I'd like to know if someone was trying to get into my house rather than someone being in my house. I'd work with the window sensors until i had them working correctly.

you are correct about the new alert regulations.

KoolKid

If money and wiring is not an issue the ideal system would be all openings protected by contacts & every room have a PiR incl hall & landing.

DublinDilbert

gizmo555 wrote: »

I've just got a quote from Eircom Phonewatch for a wireless system which includes a large number of contact/inertia sensors on all ground floor windows. There are just two PIRs - in the hall and upstairs on the landing

In my last house, I had a wireless system which had no sensors on windows at all - just the external doors. Instead, there were more PIRs.

The rationale of the installer there was that window sensors are prone to false alarms in windy weather and burglars have been known to repeatedly activate the alarm by rattling windows. When the exasperated homeowner deactivates the alarm after a couple of days, they strike.

I believe with the new Garda requirements for monitored alarms, PIRs can also be useful for verifying an activation, if they detect someone moving around the house.

Has anyone - especially someone with experience in the trade - got any advice/views which type of setup is most effective?

Thanks!

On your last system what happened when you were in the house and put on the alarm?? surely it must of gone off with all the PIRs?

PIR's are typically only good as a last resort. As others above have said best to have contacts on windows/doors. In most systems when the part guard is on the PIR's are disabled...

KoolKid

PiRs are only good as a last resort??? Please explain. They are the most reliable device for detecting someone in a given area. When you are in the house PiRs can be set for Part Guard, Access or entry so surly the Alarm would not go off.

DublinDilbert

koolkid wrote: »

PiRs are only good as a last resort??? Please explain. They are the most reliable device for detecting someone in a given area. When you are in the house PiRs can be set for Part Guard, Access or entry so surly the Alarm would not go off.

No problem. when the PIR activates this means someone is already in your house, hence its a last resort.

PIRs are not very reliable at detecting people, but are quite cheap, hence are used in domestic alarm systems. There are more reliable technologies out there for detecting people.

So when the system is set to part guard the PIRs are de-activated. If you have a system which solely relies on PIRs, like you suggested, when the system is on part guard all of the PIRs will be disabled. So what's protecting your house?

gizmo555

DublinDilbert wrote: »

On your last system what happened when you were in the house and put on the alarm?? surely it must of gone off with all the PIRs?

The system was in two zones - upstairs and downstairs. I could set it to cover the downstairs while we were upstairs. It had a delay after being set to allow you get upstairs and you also had, I think, 1 minute when you went downstairs to disarm it. Of course, this meant any intruder who got in would have had 1 minute before it went off - possibly enough to, say, grab the car keys and leg it.

I take the points made about detecting an intruder before he's inside the house, but what about the issue with inertia detectors on windows and doors being set off by gales, etc.? Is this really a problem with current systems?

Thanks again to everyone for their advice!

DublinDilbert

gizmo555 wrote: »

The system was in two zones - upstairs and downstairs. I could set it to cover the downstairs while we were upstairs. It had a delay after being set to allow you get upstairs and you also had, I think, 1 minute when you went downstairs to disarm it. Of course, this meant any intruder who got in would have had 1 minute before it went off - possibly enough to, say, grab the car keys and leg it.

I take the points made about detecting an intruder before he's inside the house, but what about the issue with inertia detectors on windows and doors being set off by gales, etc.? Is this really a problem with current systems?

Thanks again to everyone for their advice!

So if you wanted to go for a drink of water you had to turn off the alarm? :eek:

If the threshold levels are set correctly, the inertia detectors should be fine...

northdublin

the wirefree inertia sensors phonewatch use have gross and pulse count adjustment, which is adjusted via the dil sitches on the pcb so false alarms can be sorted quickly.
phone watch also use pirs as curtain beams by placing them in the reveal of the window on a narrow beam that projects across the inside of the glass. this is usually done where there is a risk of false alarm with inertia sensors, like if your house opens out onto a main st. this also means you can walk into a room while the alarm is on but cant go withing 2/3 feet of the window.

when a system is set up for part gaurd the motion sensors in the rooms off the main hall would be active but the motions in the main hall and landing would be inactive allowing for some movement, ie to get to the rkp to switch it off. this means that only the front door is protected but if you do go wire free you can get fobs and wireless remotes for opperating you system from the bedroom

KoolKid

DublinDilbert wrote: »

No problem. when the PIR activates this means someone is already in your house, hence its a last resort.

PIRs are not very reliable at detecting people, but are quite cheap, hence are used in domestic alarm systems. There are more reliable technologies out there for detecting people.

On what are you basing PiRs are not reliable?
Where are you getting they are cheap compared to a contact they are 7-10 times the price
Compared to a inertia they are between the same & 3 times the price

DublinDilbert wrote: »

So when the system is set to part guard the PIRs are de-activated. If you have a system which solely relies on PIRs, like you suggested, when the system is on part guard all of the PIRs will be disabled. So what's protecting your house?

Please read my post before answering .. Where did I suggest a system relying totally on PiRs?
On Partguard individual PiRs can be deactivated so no, ALL PiRs would not be deactivated. Whats protecting the house when the PiRs are deactivated??? The contacts like I suggested

koolkid wrote: »

If money and wiring is not an issue the ideal system would be all openings protected by contacts & every room have a PiR incl hall & landing.

fishdog

I think Stoner put it quite well with this remark:

a combination of the two is best, keeping perimeter protection is a good thing and even better when layered with PIRs. Personally I'd like to know if someone was trying to get into my house rather than someone being in my house.

Koolkid:

Whats protecting the house when the PiRs are deactivated??? The contacts like I suggested

I assume you mean the inertia sensors. Contacts alone offer little protection on windows.

KoolKid

Contacts alone are fine when combined with PiRs in every room as suggested above.
I know this would not be practicable in most cases, I am simply stating what is the most reliable system . Remember large commercial buildings would very rarely use inertia sensors.

fishdog

Remember large commercial buildings would very rarely use inertia sensors.

I agree, but the OP said:

There are just two PIRs - in the hall and upstairs on the landing

Therfore he is not talking about a commercial building.

Most installers would reccomend installing inertia sensors when alarming the average house (contacts and PIRs too).


I will be doing this myself in the morning!

I still think stoner summed it up best.

KoolKid

You are missing my point. In a house yes inertias are what I would normally recommend.
But what I was explaining was the best & most reliable system If money and wiring is not an issue..

Ofcourse in mose houses money & wiring is an issue. And in that situation I would be recommending all POE be protected by inertai/contact & a minimum of 2 PiRs especially if monitored.

fishdog

Fair enough KoolKid, the commercial bit just seemed out of context.

Perhaps the best thing to do is to save up and do the job right if money is an issue. Or go basic first and upgrade later.

BTW I would only go wireless if I had no other option.

KoolKid

Why do you feel the wireless is unreliable?

fishdog

Why do you feel the wireless is unreliable?

That is not what I said. I said:

I would only go wireless if I had no other option.

Although I agree that wireless sensors have their uses if there is a cable there I will use it.
On the down side wireless sensors:

1) Cost more duing the initial install (generally) and to replace.

2) They require a battery each (which has a finite life, although this has improved). 20 sensors = 20 sensor batteries, that will all need to be replaced someday.

3) They are more bulky by their nature.

4) They are not as reliable as hard wired sensors.

5) If the signal can not penetrate various walls etc additional equipment is required, more expense.

6) Compared to a standard inertia sensor, there is a lot of complex electronics. There is simply more to go wrong. I do admit they have improved.

I could go on.....


Many new builds come prewired. In such houses a wireless alarm is not the best option. If a hard wired alarm is installed properly it should do all you want at a far better price than a wireless system.

Sometimes simplicity is best. Other times a wireless sensor is the only sensible choice.

gizmo555

koolkid wrote: »

But what I was explaining was the best & most reliable system If money and wiring is not an issue..

Well, wiring is not an issue. Since the house is not pre-wired and I don't want the hassle of installing a wired system now, I will go wireless. I take fishdog's point about the added bulk and need to replace batteries on wireless systems, but I'll have to live with that.

On the money side, it's not a huge issue - Phonewatch are pricing wireless PIRs at €80. I could add half a dozen to cover all the ground floor rooms and only add about 18% to the overall system cost, but have a considerably more effective system with the ability to verify alarms for the purposes of Garda callouts.

Thanks again to everyone for their input!

KoolKid

your welcome.

fishdog

Thanks again to everyone for their input!

No bother. If you have no wiring in perhaps wireless is the way to go.

You should shop around. Paying for the system is only part of the cost. There are other charges too and prices vary alot!

northdublin

on the subject of wireless alarms, they are not completely wireless so do expect some cabling even on a very neat install
firstly mains has to be supplied to the panel from a socket or fuseboard and wired trough a spur.
second....if connecting a monitored alarm a patch to the phoneline is needed.
thirdly .......if you require an exterior ringing bell which i would recomend this will also need a cable from the panel to the exterior, usually trough the attic.
and finally if you hve a large house the system might need a second sounder incase the one in the panel cant be heard from other parts of the house and this would require a cable.
i have had ppls jaws drop as soon as i mentioned cables when installing wire free alarms, and its just down to the sales ppl not informing the customer about it

fishdog

they are not completely wireless

That is a good point.

if you require an exterior ringing bell which i would recomend

Yes I agree 100%. I think this should be a mandatory for all alarms. This is often left out to make installation quicker, neater and cheaper. The cost: reduced security.

if connecting a monitored alarm a patch to the phoneline is needed.

This is normally the case.

You could install a GSM module (or radio link). True it is more expensive, but unless you are going to protect the phone line from attack you are not offering much security by relying on it. Phone lines are so vulnerable to attack is a joke. But I agree with northdublin because very few installations have this.

mains has to be supplied to the panel from a socket or fuseboard and wired trough a spur.

The best way would be to install the panel in the attic and supply it from a lighting circuit. It could then supply the outside bell box with no mess or fuss. A GMS module would give it a phone line and then multiple sounders could be installed upstairs with ease and neatness. Wireless keypads are available, so wiring the key pad would not be an issue.

But in the real world very few installers will go to this sort of effort and very few customers know that this is possible. The result is what northdublin described, wires for your “wireless” alarm!

northdublin

The best way would be to install the panel in the attic and supply it from a lighting circuit. It could then supply the outside bell box with no mess or fuss. A GMS module would give it a phone line and then multiple sounders could be installed upstairs with ease and neatness. Wireless keypads are available, so wiring the key pad would not be an issue.

But in the real world very few installers will go to this sort of effort and very few customers know that this is possible. The result is what northdublin described, wires for your “wireless” alarm!

most of the major alarm companys will not allow their installers to fit panels into attics. the reason i was given by one of the major installers is for various health and safety reasons ie fibreglas, risk of falling trough the ceiling ect.
they said this mainly applies when the system is to be serviced.
my response was its ok for installers to go up there but not service engineers, they basicaly said yes.
they also stated that the panel would be in an unprotected area of the premises and if someone lifted slates they could get in and access the panel without tripping the alarm.
my response was........duel tech pir.
ive put a few panels in attics but most have been wired systems where ive had to pull the cables out of the insideof a hot press where you cant fit panels anymore but for some reasons builders and sparks keep wiring them to the hot press. so rather then breaking trough into one of the bedrooms the attic is te better option.

also on the topic of the gsm it needs cabling too and the company i installed them for insisted that they be away from the main panel.
as you know the rkp is built into the main panel on the wire free and its usually in the hall or a closet downstairs so having the gsm under it was a no no, so it had to be out of sight of the panel incase a theif targeted it for destruction

fishdog

as you know the rkp is built into the main panel

Take the Eircom "wireless" alarm for example, the keypad is on the panel (a giant step backwards!), but a remote wireless keypad is also available.

most of the major alarm companys will not allow their installers to fit panels into attics

I know, how convenient saving all that time!

the reason i was given by one of the major installers is for various health and safety reasons ie fibreglas, risk of falling trough the ceiling ect.

I think you believe that as much as I do! How do us sparkies manage to wire houses? Did they ever hear of dust masks?

they also stated that the panel would be in an unprotected area of the premises and if someone lifted slates they could get in and access the panel without tripping the alarm.
my response was........duel tech pir.

My reply too! They are alarm installers FFS if they are worried about an area being unprotected, simply protect it! It does not seem to bother them much that the phone line is unprotected!

also on the topic of the gsm it needs cabling too and the company i installed them for insisted that they be away from the main panel.

This is a "makieuprule" that should not apply when the panel is in the attic as it will have "rung out" before an intruder could possibly get to it.

If a thief destroys the panel, which most installers put in an easy to find and get at location it does not matter if the GSM module is attacked or not so why bother having it remote to the panel??? BTW Eircom recently put the GSM module on top of the panel in my neighbour's house.

northdublin

they also do a wired rkp for the larger concord panel......this imo is much better then the wireless remote for the reason that to know if you have opperated the alarm propperly the panel tells you via an audio message which if you are not in hearing range of the panel is a waste of time. to combat this they fit a wired speaker which is seriesed in with the speaker on the panel.
so if you have to run a wire for the speaker why not just run a wire for the rkp?

eire-kp

Im also building a house at the moment and installing an alarm. Im currently thinking of puting in just pirs. The ony contacts will be on a gun safe. Any jobs i have been on eg schools have just pirs, the only contacts have been on door access/realese systems this seems to work fine. Another reason is i dont feel like drilling contacts on to the new alluminum windows . Maybe im wrong?

KoolKid

If possible you should be looking at all accessible openings at least

Stoner

eire-kp wrote: »

Im also building a house at the moment and installing an alarm. Im currently thinking of puting in just pirs. The ony contacts will be on a gun safe. Any jobs i have been on eg schools have just pirs, the only contacts have been on door access/realese systems this seems to work fine. Another reason is i dont feel like drilling contacts on to the new alluminum windows . Maybe im wrong?

well as you know, with places like schools or open plan offices there are too many Windows to cover with contacts so PIRs are an economical option

fishdog

Im currently thinking of puting in just pirs. The ony contacts will be on a gun safe

A basic alarm system and safe is generally enough to satisfy the local crime prevention officer (CPO) for a small rifle (.22) or a shotgun. But not using inertia sensors will seriously reduce your security.


If you are looking for a firearm that is on the restricted list (this would be mainly centre fire rifles or pistols/revolvers of any calibre) your alarm system will have to be much more comprehensive. A few years ago I installed systems for several individuals that were applying for restricted firearms certificates. The CPO was very fussy (rightly so) about the standard of the alarm system. Clearly he had received special training on intruder alarm systems. I spent about an hour showing him the system and demonstrating its operation. He insisted on back up protection for the phone line, every possible entry point had to be covered with an inertia sensor and more than 1 PIR was required. The gun safe required a separate code to be entered so as the safe could be opened as well as being on its own 24 hour zone.

That was just for starters!