Heat Detectors for the Attic

[Mike]

This one is easy (I think), are 135 degree heat detectors ok for attic use or do you need the 200 degree ones in general? I know attics get hot in general but not more than 135 degree without 'help', right?

 

[upstatemike]

While I understand your logic I have never heard of anyone putting 135 degree heat detectors in an attic. I guess it depends on the type of roof you have and what part of the country you live in. Maybe also a regulatory issue?

 

[AutomatedOutlet]

They certainly get over 135 degrees here in Texas!

 

[Mike]

Maybe I was off, I thought I read it was recommended (several considering the space involved), I also thought putting heat detectors in the garage as well.

I'll see if I can remember the source, but if this is not generally recommended or done, I have more than enough projects...

 

[upstatemike]

I have 135 degree rate of rise devices in the garage but use 200 degree fixed devices in the attic.

 

[HighTest]

Just curious, what are the sensors for? Is there concern that your asphalt shingles are going to melt? Fire concern?

Or is this for controlling a vent fan that would turn on in high temps?

If you have high temps on average, you may wish to read this article:

http://www.naturalhandyman.com/iip/infattf...nfattfan3a.shtm

While insulation is our friend, if your attic isn't properly vented it'll radiate heat back into the living space through the night from that hot attic. Many compensate by turning up their AC system and spend more $ when a properly vented attic may save them $ by reduced AC costs in the summer. When done properly it doesn't necessarily make you colder in the winter either.

 

[WayneW]

My understanding is that heat sensors are a more reliable way to detect fire than smoke detectors since heat detectors have a very low false alarm rate. Although I have heard that smoke detectors may be faster to respond, which is why they are used in the prime life safety areas. Heat detectors are great in the garage where auto exhaust fumes and in the kitchen where cooking fumes, etc may create false alarms.

 

[Mike]

Just curious, what are the sensors for? Is there concern that your asphalt shingles are going to melt? Fire concern?

I'll have to find where I read this, but I was just trying to cover all the bases on smoke/fire/co2 detection, and heat detectors for the attic and garage had been mentioned so I was looking to cover those aspects.

It is not to control an attic fan (these detectors are generally one-time use anyway, you replace them if they trigger).

I had thought it was recommended to use heat detectors in those areas as they are prone to false alarms and would cover the condition of a fire starting in those areas (as unlikely as that may be, also noting the detectors are fairly inexpensive so I was not worried about the cost (less than $100 for everything even if using a bunch of them).

I'll look around to see if I can find the source. It sounds like it is definitely not standard practice from the reactions I am getting.

 

[upstatemike]

Just curious, what are the sensors for? Is there concern that your asphalt shingles are going to melt? Fire concern?

Or is this for controlling a vent fan that would turn on in high temps?

If you have high temps on average, you may wish to read this article:

http://www.naturalhandyman.com/iip/infattf...nfattfan3a.shtm

While insulation is our friend, if your attic isn't properly vented it'll radiate heat back into the living space through the night from that hot attic. Many compensate by turning up their AC system and spend more $ when a properly vented attic may save them $ by reduced AC costs in the summer. When done properly it doesn't necessarily make you colder in the winter either.

Attic fire detectors are very important because attics have a lot of exposed dry wood that will cause any fire to escalate quickly. Also attic areas are common to large areas of a house so a fire spreads much more quickly to engulf the entire building than would be the case of a fire down in one of the segmented living spaces. Protecting asphault shingles is not the issue (although much of the roofing in my area is wood shingle, even brand new ones).

Attic venting is always a requirement to prevent condensation buildup irrespective of any energy concerns. This will not guarantee that temperatures will stay below 135 degrees however so 200 degree detectors are a good idea.

Heat detectors are cheap so use plenty of them. They will work on a 4-wire fire zone so you can use any spare zone on an Elk or other fire/security panel. You should probably make the attic an isolated zone so you will know right where to go if there is a problem. Always use end of line resistors on fire zones so you know right away if there is a wiring problem and protection has been compromised.

 

[AutomatedOutlet]

I'm planning on adding a temp sensor to my attic. That way, based on time of year and outside temperature, I can adjust the ventillation.

 

[jlehnert]

Like many things, usage varies depending on were you are.

As has been mentioned before, the heat sensors mentioned in this thread are the security system type. Usual practice is to use 135 in the garage and living areas, and 190 in attics. The main reason for heats in the attic is early detection of fire in that area. The usual fire causes are lighting strikes, and chimney fires.

 

[Mike]

Thank you. Mine are on order. Great point on the 135 for the garage, I had 194 degree detectors in mind and forgot that the lower heat value is more appropriate for the garage.