Smoke Detection Configuration Help Needed

[chrisexv6]

Yeah, I forgot to make it clear...I did not put a CO at every smoke. I put 1 CO on each floor of the house including the basement. I have smokes all over the place, but only 3 CO detectors total.

I never thought about a CO directly in the ductwork...all of the detectors I looked at said not to put them near vents/returns, presumably because of dust messing with the sensor. Ive seen a few duct-based CO detectors and they were far from inexpensive. Might be good for a commercial install, but even I think it might be overkill for my average size house.

 

[apostolakisl]

Yeah, I forgot to make it clear...I did not put a CO at every smoke. I put 1 CO on each floor of the house including the basement. I have smokes all over the place, but only 3 CO detectors total.

I never thought about a CO directly in the ductwork...all of the detectors I looked at said not to put them near vents/returns, presumably because of dust messing with the sensor. Ive seen a few duct-based CO detectors and they were far from inexpensive. Might be good for a commercial install, but even I think it might be overkill for my average size house.

It would be nice if they had smoke/co in one detector to avoid the clutter. But it would be a little complex since they would have to alarm independently. You would need an extra conductor and an installer who does mix them up.

 

[newalarm]

Just to recap, I have my CO in the hallway just outside of the furnace/utility room. I figure this is more of a living space and therefore more critical. Is that the best location? They are separated by a door. I could add one in the furnace room, but would like to avoid cost...

 

[chrisexv6]

I *dont* have a CO detector in my utility room on purpose. Id worry it would false (granted, if you are getting enough CO from it to set it off, you might want to get out of the house). Granted, I have one on each of the other floors as well, so if CO made it there then we'd be alerted, and I think thats more important because you are going to be on your living/sleeping floors for longer periods than your utility room.

Do you have any more CO detectors in the house? If so, I dont think Id worry about putting one IN the utility room.

 

[newalarm]

Yes, one on each floor. I had the same reasoning.

Thanks.

 

[apostolakisl]

Just to recap, I have my CO in the hallway just outside of the furnace/utility room. I figure this is more of a living space and therefore more critical. Is that the best location? They are separated by a door. I could add one in the furnace room, but would like to avoid cost...

CO should not leak out of any heating equipment. So co in your furnace room would not be a false alarm, it would indicate malfunction.

 

[Del91574]

CO should not leak out of any heating equipment. So co in your furnace room would not be a false alarm, it would indicate malfunction.

First, in regards to another post, NO DETECTOR, should be installed in supply or return air unless it is specifically listed for such, no exceptions. The plastics typically used for the detectors and housings would contribute to another problem, hazardous fumes being distributed throughout a house. Even duct detectors are not installed within the detectors, only the sampling tubes/ports.

Second, the assumption above is not true.

CO is produced by incomplete combustion, so unless you have a furnace or HWH that is 100% efficient (they don't exist) some form of CO is always going to be produced. Where that CO goes depends on plenty of other factors, however, most of the detectors I know of have a minimum installation distance from any fossil fuel burning appliance, as well as away from drafts and breezes/windows.

Heat exchangers in furnaces crack relatively often and in the case of other units that vent directly out the side of the house via PVC pipe, it's the same item, granted the exhaust gasses are cooler than the older units, but there were large problems with a bunch of them causing the piping to overheat and crack.

 

[apostolakisl]

First, in regards to another post, NO DETECTOR, should be installed in supply or return air unless it is specifically listed for such, no exceptions. The plastics typically used for the detectors and housings would contribute to another problem, hazardous fumes being distributed throughout a house. Even duct detectors are not installed within the detectors, only the sampling tubes/ports.

Second, the assumption above is not true.

CO is produced by incomplete combustion, so unless you have a furnace or HWH that is 100% efficient (they don't exist) some form of CO is always going to be produced. Where that CO goes depends on plenty of other factors, however, most of the detectors I know of have a minimum installation distance from any fossil fuel burning appliance, as well as away from drafts and breezes/windows.

Heat exchangers in furnaces crack relatively often and in the case of other units that vent directly out the side of the house via PVC pipe, it's the same item, granted the exhaust gasses are cooler than the older units, but there were large problems with a bunch of them causing the piping to overheat and crack.

CO is never supposed to be in the house. It is two different things to make co and to let it go anywhere but out the exhaust. And modern furnaces produce very little co. The air/gas mixture is tightly controlled. But by all means, don't you worry about CO in your furnace room OK. . .just let it hang out there it is normal right.. . at least according to you.

And yes, duct detectors are duct detectors. Sampling tubes and all. I have two of them.

But again, furnaces have the exhaust fan on the outbound side (they suck from the heat exchanger), and the air handler blows into the heat exchanger (positive pressure). This is not an accident. .. it is absolutely on purpose. It designed that way so should a small crack occur, combustion byproducts don't get into the household air.

So, if your furnace was designed prior to 1980, you probably have a passive flu that goes up because hot air rises. Otherwise you have a system like I described. Since it is the odd furnace that hasn't been replaced after 30 years of service, you probably don't have that kind.

 

[Del91574]

Lou, again, you know best.

Keep in mind, about 5 posts up you were suggesting installing a CO detector inside a plenum or a system, with the air velocity and no regard to introducting plastic and wiring to the air supply. Strange how every manufacturer of commercially sold detection equipment specifically says to not install them in an enviroment like that, as well as the danger of introducting the plastic (and cable insulation, plenum rated is still not supposed to be installed within ductwork) into a duct system. Shudders.

Talk to the guys with the jackets, axes, and funny hats and let them bring a meter in to any furnace room. CO will exist in some shape or form in an extremely high percentage of perfectly functioning systems, whether it goes out the chimney or exists in a very trace amount, it's there. It's the nature of the beast. Don't want CO, then you're looking at all electric as a "fuel". I don't have the money to purchase a sampling meter as expensive as them, but I've been around plenty of times on plenty of certifications, as our state has a mandate for new construction. There's a difference in ppM of "trace" vs. what sets off a CO detector, as well as the type of sensing element within the detector itself. There's a reason why furnaces get red tagged because of their HE's, and it's not just because the design is "inherently safe" they don't.

 

[apostolakisl]

Lou, again, you know best.

Keep in mind, about 5 posts up you were suggesting installing a CO detector inside a plenum or a system, with the air velocity and no regard to introducting plastic and wiring to the air supply. Strange how every manufacturer of commercially sold detection equipment specifically says to not install them in an enviroment like that, as well as the danger of introducting the plastic (and cable insulation, plenum rated is still not supposed to be installed within ductwork) into a duct system. Shudders.

Talk to the guys with the jackets, axes, and funny hats and let them bring a meter in to any furnace room. CO will exist in some shape or form in an extremely high percentage of perfectly functioning systems, whether it goes out the chimney or exists in a very trace amount, it's there. It's the nature of the beast. Don't want CO, then you're looking at all electric as a "fuel". I don't have the money to purchase a sampling meter as expensive as them, but I've been around plenty of times on plenty of certifications, as our state has a mandate for new construction. There's a difference in ppM of "trace" vs. what sets off a CO detector, as well as the type of sensing element within the detector itself. There's a reason why furnaces get red tagged because of their HE's, and it's not just because the design is "inherently safe" they don't.

Dell,

You are plain wrong.

CO should not be in a furnace room at levels unfit for human respiration. In other words, a CO detector should not sound an alarm in a furnace room. In fact, I just read where commercial building codes are requiring CO detectors in any room with a permanently installed fuel burning device (ie the furnace room)

Trace amounts of CO exist everywhere even without humans. CO detectors don't detect trace amounts because they would always alarm. . . even on a sailboat in the middle of the ocean. That would make them quite useless. CO detectors detect levels of CO that are unfit for human habitation. If your furnace room has levels unfit for human habitation, well that is bad.

Sorry if I didn't say put a plenum detector in a plenum. Perhaps not as self-evident as I thought.

Ive seen a few duct-based CO detectors and they were far from inexpensive.

Holy smokes. I just priced one. I thought they would be like the smokes . . . wow. .. $500.

 

[newalarm]

I did not see any guide for the CO1224T about how far from appliances it should be located. Here is quote from manual:

For example, Chapter 5.5.5.3.1 states that carbon monoxide detectors
shall be installed in accordance with manufacturers published instructions
in the following locations:
(1) On the ceiling in the same room as permanently installed fuel
burning appliances
(2) Centrally located on every habitable level and in every HVAC zone
of the building

I guess I will install one on the ceiling of the utility room. the furnace is in a separate room, but I would like to avoid installing two. the furnace room opens into main utility room where gas heater is installed, and where I want to install CO.

 

[chrisexv6]

I did not see any guide for the CO1224T about how far from appliances it should be located. Here is quote from manual:

For example, Chapter 5.5.5.3.1 states that carbon monoxide detectors
shall be installed in accordance with manufacturers published instructions
in the following locations:
(1) On the ceiling in the same room as permanently installed fuel
burning appliances
(2) Centrally located on every habitable level and in every HVAC zone
of the building

I guess I will install one on the ceiling of the utility room. the furnace is in a separate room, but I would like to avoid installing two. the furnace room opens into main utility room where gas heater is installed, and where I want to install CO.

System Sensor has a general CO detector guide on their site, in it are some recommendations for placement. You can also Google CO detector placement and see a ton of info.

It may be that no one document stated no detector near sources of combustion, but to me its similar to putting a smoke detector in a kitchen. At some point along the line its going to false. In my case, the CO detector in my basement is about 15-20' away from my combustion utilities. If they really are leaking that much, it will get to that detector pretty quickly. Plus I have forced air heat, so chances are the CO would make it to the other floors in the house pretty quickly as well.

 

[ddennerline]

Why is hasn’t any CO2 sensor manufacturer created an alarm compatible CO2 detector with a digital level display? The current CO2 sensors will not trip until there’s a clear health risk. I wanted to add CO2 alarms to my Elk, but place them closer to potential risk sources – such as hot water heater, furnace, range etc. I could not find any CO2 alarm with digital displays similar to Kidde Nighthawk. Even better combination gas and CO2 (http://www.firstalert.com/detectors/plug-in/explosive-gas-co/gco1cn). I really want one of these with form-C relays.

 

[Del91574]

Dell,

You are plain wrong.

CO should not be in a furnace room at levels unfit for human respiration. In other words, a CO detector should not sound an alarm in a furnace room. In fact, I just read where commercial building codes are requiring CO detectors in any room with a permanently installed fuel burning device (ie the furnace room)

Trace amounts of CO exist everywhere even without humans. CO detectors don't detect trace amounts because they would always alarm. . . even on a sailboat in the middle of the ocean. That would make them quite useless. CO detectors detect levels of CO that are unfit for human habitation. If your furnace room has levels unfit for human habitation, well that is bad.

Sorry if I didn't say put a plenum detector in a plenum. Perhaps not as self-evident as I thought.



Holy smokes. I just priced one. I thought they would be like the smokes . . . wow. .. $500.

Lou,


Yep, you're right regarding the trace amounts, but then again, once that furnace or HWH fires...nope, nothing changes in the enviroment. Of course, now you're going to argue that CO stratifies in the air. I also would wager that you didn't look into the levels and time periods prescribed within the standard and detectors for an alarm in addition to what is considered trace, elevated, and hazardous for human respiration.

Prior to soapboxing on what is incorrect or wrong, I'd recommend taking a look at the installation documents and standards. I would direct you to page 3 of SS's 1224T, left hand side of the page for starters that directly contradict your statements....in the manufacturer's own words. I'll point out these links for you to review at your leisure. http://www.systemsensor.com/pdf/SCFL001.pdf http://www.systemsensor.com/co/pdf/CO-5-things-to-know.pdf.

I forget, what do you do for work with regarding system design, installation and maintenance? I must be missing something in what I deal with on a daily basis? I'd fax or email my trade licenses and NICET certifications and my company's OEM status, maybe have a fire marshal provide you some information also, but honestly, I've got nothing to prove to you

@ NEW/Chris: CO installation criteria is covered in NFPA 720.The installation instructions can't be used as a design criteria, they only provide the enviromental and general information, like smoke detectors. I can't find the hard numbers on the present versions of the CO1224's, however the equivalent (same element and technology) 250-CO list 10'.

@ dennerline, for CO (assuming the extra oxygen molecule is in error) I believe, if you look at the chart on the CO1224's, I'd call the response appropriate to provide a valid alarm and keep nuisance alarms at a minimum, since in the end, we're dealing with a chemical element that can't be electronically compensated for drift like a PE detector. The Nighthawk units are better than nothing, however their sensing element is a different technology than an alarm system CO.