# Hardwired Smoke Detectors



## WNYcarpenter (Mar 2, 2007)

Is there a way to prevent false alarms?

Most of our new projects have hardwired systems...smokes, high water, low temp connected to an alarm system.

The alarm company calls the home owner, the fire company, and down the list of contacts. The biggest problem we have, the only one really, is the smoke detectors are too sensitive??

The day before yesterday, there was another alarm at one of our prominent clients' properties...Nothing was wrong.... The client called kinda upset about the disruption. It happens more than it should, its embarrassing and expensive. 

I also talked to one of our guys on the crew who volunteers with the fire company and said they're tired of all the false alarms with these security systems. This is a pretty common occurrence/annoyance and is more frequent when additional homes are upgraded each year. I believe it's code to have hard wired systems... and an optional alarm service. Most if not all HOers opt for the alarm system since theses are vacation properties. 

The client wants the alarm company to solve the problem since they subscribe to the service and don't want to continue paying for service calls when the system is possibly malfunctioning.. Seems legitimate....a technician came today and monkeyed with the wiring on one of the units and said it was fixed. I don't know what they did, and I have no reason to doubt them.....It's kind of a wait and see I guess.

I'm doing the service calls, and winter surveillance...Is there any regular maintenance I can do?? Maybe carry a can of compressed air to blow the detectors out. I also carry a stock of 9volt batteries. 

Any thoughts?


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## Tinstaafl (Jan 6, 2008)

Are the falses occurring in empty houses, or occupied? If occupied, there's always a certain percentage of falses that aren't really false; just someone cooking, smoking or whatnot. Not much you can do about that unless it's due to a cheap brand just not being well enough calibrated.

If they're happening in empty properties, you might want to look for a common element like the type of heating system they have--and what it's set for. Interesting problem. Glad it's yours. :laughing:


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## WNYcarpenter (Mar 2, 2007)

Tinstaafl said:


> Are the falses occurring in empty houses, or occupied? If occupied, there's always a certain percentage of falses that aren't really false; just someone cooking, smoking or whatnot. Not much you can do about that unless it's due to a cheap brand just not being well enough calibrated.
> 
> If they're happening in empty properties, you might want to look for a common element like the type of heating system they have--and what it's set for. Interesting problem. Glad it's yours. :laughing:


There's a 9 week summer season that these residences are occupied 24/7, then throughout the year they're vacant, aside from holidays and such. Then there's me walking through once a month, so I feel kinda responsible....

during the season it's burnt toast etc...but it isn't uncommon to have such calls in the middle of January, though not as frequent.


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## Tinstaafl (Jan 6, 2008)

Well, I assume that like any good cowboy you take a shower every Saturday, so it's probably not you. :laughing:


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## 480sparky (Feb 1, 2009)

I got a nickle that says the units are older ones, and have a ton of dust built up that could easily be removed by taking a vacuum brush to them. :whistling


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## WNYcarpenter (Mar 2, 2007)

Tinstaafl said:


> Well, I assume that like any good cowboy you take a shower every Saturday, so it's probably not you. :laughing:


Now ya got me thinkin':whistling


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## WNYcarpenter (Mar 2, 2007)

480sparky said:


> I got a nickle that says the units are older ones, and have a ton of dust built up that could easily be removed by taking a vacuum brush to them. :whistling


would compressed air set them off if I blew them all out on my surveillance route?


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## 480sparky (Feb 1, 2009)

WNYcarpenter said:


> would compressed air set them off if I blew them all out on my surveillance route?



I would be more concerned with physical damage than a nuisance trip.


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## Tinstaafl (Jan 6, 2008)

480sparky said:


> I would be more concerned with physical damage than a nuisance trip.


Translation: Compressed air could conceivably damage components or drive the dust even deeper into places it shouldn't be. Vacuum is much less likely to do either. :thumbsup:


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## flashheatingand (May 3, 2008)

480 the dust build-up makes sense, but, wouldn't the dust act more of an insulator? Don't get me wrong, It would be a good service to vacuum all the sensors / detectors. Just, for troubleshooting purposes, pointing out that I believe dust and the insulation thing. Been wrong before, not afraid of it, if so, I appreciate the heads up.


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## WNYcarpenter (Mar 2, 2007)

480sparky said:


> I would be more concerned with physical damage than a nuisance trip.





Tinstaafl said:


> Translation: Compressed air could conceivably damage components or drive the dust even deeper into places it shouldn't be. Vacuum is much less likely to do either. :thumbsup:



I hope you understand when I say, I'll change batteries and deal with "nuisance trips" instead of vacuuming all the smokes in 29 residences.:laughing:


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## WNYcarpenter (Mar 2, 2007)

is there a life expectancy for smokes...we know the date of the installs, should we recommend having them serviced/changed in x amount of years?


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## Tinstaafl (Jan 6, 2008)

flashheatingand said:


> 480 the dust build-up makes sense, but, wouldn't the dust act more of an insulator?


Many smoke detectors use optical sensors to decide there's smoke in the air. If it can't see the light, there must be a fire.



WNYcarpenter said:


> is there a life expectancy for smokes...we know the date of the installs, should we recommend having them serviced/changed in x amount of years?


Yep, every 8-10 years.


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## SemiRetiredEL (Nov 24, 2009)

Smokes may be optical or nuclear. As pointed out dust between the light or nuclear source and the detector will be interpreted as smoke and set them off.

I would expect the most false trips would occur on homes that have resistive strip heat that have accumilated dust on the strips. The first time the strips (emerg. heat or aux. heat on a heat pump) are energized after the summer rest you can smell the dust balls burning off and hear the alarms sounding.

A little vaccuum in the Fall, changing the batteries and replacing the 10 year old units, would probably save lot of grief.


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## 480sparky (Feb 1, 2009)

flashheatingand said:


> 480 the dust build-up makes sense, but, wouldn't the dust act more of an insulator? Don't get me wrong, It would be a good service to vacuum all the sensors / detectors. Just, for troubleshooting purposes, pointing out that I believe dust and the insulation thing. Been wrong before, not afraid of it, if so, I appreciate the heads up.




It's not an issue of insulation/conducting. It's a matter of the transmission of light. Photo-electric smokes use a beam of light across an open space and measure it with a photocell at the other side. If the light isn't as bright as it should be, it assumes there's smoke and sounds the alarm. 

Dust inside a unit has the same effect.... it merely cuts down on the light the photocell receives.


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## ABLE1 (Apr 30, 2005)

Ok guys it is time to make your brains like a sponge. Education Time!!

The majority of Smoke Detectors that are used on Residential Alarm panels use a photoelectric beam technology for sensing smoke. 

This far different than those that you buy at Kmart or HD that are either battery operated or those that are FCC (interconnected) with battery backup. Those units use a ionization chamber that ionizes the air by a small bit of radioactive material. These units are cheaper to produce and are more prone to an alarm due to cooking fumes and such. Since they only make audible inside the house this is not a big deal, just a PITA.

The alarm panel P/E type have a chamber that has a photoelectric emitter (infrared) and a photoelectric receptor. These are positioned at about 90 degrees to each other and are inside of a black chamber. During normal conditions the infrared light that is produced is absorbed by the black. However when smoke enters the chamber the light bounces off the particles and into the receptor. The amount that is picked up is important to understand. If the amount reaches say 50%-80 or even 90% nothing happens. But when it hits 100% it is alarm time. 

Now if you have followed the process to this point you should see that these detectors are not as sensitive as you might think. What is confusing to most people is that they don't see any smoke and it went into alarm. Well there is a simple reason. The smoke detectors can't tell the difference between dirt, dust and SMOKE. Over time the sensor chambers get dusty and dirty. It is recommended by the NFPA that the detectors be cleaned every 12 months. (aka 1 year). If this is followed the odds of a false fire alarm is minimized. The problem is that most people do not want pay for the service call, that is until after a false alarm. 

End of Chapter One

Les


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## flashheatingand (May 3, 2008)

Learn something new everyday. Thanks guys.


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## ABLE1 (Apr 30, 2005)

Ok,

Where were we.

It is obvious that the smokes need to be cleaned. But how to do it??

This all depends on the manufacture model of the detector. Some can be disassembled and the chamber blown out and reassembled. Some provide replacement chambers that just pop in and your done. There was one model from years ago that had a procedure of taking a bucket of water with a amount of soap. Throw in the smoke detector for 10 minutes, and then rinse in a bucket of fresh water and then let dry for 24 hours before re-install back into the system. Really hated that one.

I have suggested to my customers to do the following. Not that they all do it but I did tell them. In a residence I tell the "vacuum cleaner person" that as they in vacuum mode to place the brush on the wand and just run it around the detector. It will not give it a 100% cleaning but it will help. For commercial applications (schools) I have helped design a PVC cup that fits of a specific detector. Holes are drilled in the circumference that directs jets of air toward the sensing chamber. This is then necked down to the size of their vacuum cleaner. (back pack mounted). They have a person twice a year on smoke clean duty. Raise the vacuum to the smoke put it in place and suck for 1 minute. This procedure has greatly reduced their false alarms. 

Now there is one other detector that can communicate to the panel or Central Station that it is getting dirty and need cleaned. To take advantage of this you really need to be in the alarm business.

A last issue that needs to be discussed and that you will have little control over. And that is SPIDERS Smoke detectors do have bug screens to keep them out but I have seen spiders that are so small (babies) that think the dark chamber is a good place to make a home. They themselves reflect the light just like smoke. And when they decide to build a web.......... well do I need to explain that part??

Locally, when a customer is having any kind of construction going on I suggest that they bag the smokes in the morning before for the dust starts and then after clean up at the end of the day remove the bag. This is not 100% but it sure does help.

Ok, I think that is end of Chapter 2 and end of the education session.

Hope that helps.

Les


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## WNYcarpenter (Mar 2, 2007)

Thanks ABLE1...:thumbsup: I guess I'm the "vacuum cleaner guy"

great info!!


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## ABLE1 (Apr 30, 2005)

One more point that needs to be made. If you are going to get into this it is very important to avoid the WHOOPS, is to place the system ON TEST with the central station while you are doing your thing. This will require authorization to do so. 

You can not just assume that calling the alarm company or the central station and telling the person that answers that you need the account on test so you can do some cleaning or what ever. To them you are just a voice on the other end of the phone line. You will be asked your name, the account number and your central station passcode. You don't have that you are consider a non-person and may get the police dispatched on your butt.

You can tell them you life story but with out the proper information you will get no where.

The rule would be to place on test of a time frame that when it times out will go back to normal. The customer needs to authorize you with a special code and you need to understand and accept the responsibility and liability of what you are doing. This is the serious stuff. Mistakes happen and if there is a false and it is your fault the liability rest on you after your customer. I would suggest a conversation with the alarm dealer to get their opinion.

Concerning the vacuum sucker, make sure it fits the smoke you are cleaning. And the air flow does the most good. If not, it is not worth the time. It will take some trial and error to get it right.

End of Chapter 3


Les


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