Heat detector - what does it do?

[Cameronl]

I have a couple of these in my house (pic not mine):

It's an older house (built 1947), and I've been staring at one over my bed for the last 8 years...

It says it a heat detector, but what I don't know is, what does it do? Some sort of alarm? Is it powered? Is it connected to an buzzer somewhere in the house or does it make its own noise? Is there a way to reset it if it goes off for some reason?

I've done some google searches, but can't find any info about how they work.

 

[Buckgnarly]

Subscribed...they are all over my school too!

 

[mx185sw]

if they are part of the alarm system.. they detect rapid rise in temp (example: 25 degrees in a min).. which would indicate a potential fire issue. Since smoke detectors are not to be used in rooms with fireplaces.. installers will use heat detectors for fire alarm triggers.

Note: the numbers in the example are just that.. not real life numbers or "Rate of Rise" that varies with the model and option you choose.

Hope that helps.

 

[n8n]

Pull it down, short the terminals together and find out

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[Milton Shaw]

Some of those early heat detectors were non electrical. They had a spring wound up that would ring that bell when the heat link melted. As mentioned above they respond to the heat rise and would go off when they hit somewhere around 135 degrees.

 

[Cameronl]

I am not aware of any larger alarm system in the house. I have just two, one in the living room (with a fire place), one in the master bedroom. I guess I could unscrew one and see if it's hardwired of has a spring.

We of course have modern one alarms through out the house.

 

[Jlbc212]

If you have hard-wired smoke detectors in the house, the heat detectors should be wired in with the smoke detectors. Some heat detectors are rate-rise-detectors as other posters have described. Some heat detectors are fixed heat detectors, that is, the heat detector will trip an alarm when the temp at the detector reaches a set temp, such as 185 degrees. Other heat detectors are a combination of both rate-of-rise and set temp.

 

[DenisG]

Looks like this one:
http://www.iowaind.com/Manufacturin...thermodetector-thermostatic-switch-4255-2.asp
or
http://dan.calvinet.com/html/simplex_4255-1.html

 

[Kaizen]

if there are wires test for voltage. guessing they were from an old system. never seen spring ones before. those would be cool to see. probably didn't want to deal with the hole in the ceilings so they left them there.

 

[n8n]

If they're not being used and you want to demo them, someone who does FA systems professionally might want them as desk toys (ahem...)

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[Cameronl]

Thanks all for the input. I'll investigate closer. I have no idea if they are active.

 

[djjsr]

Those are cameras. Your neighbor installed them before you bought the house. You may be an internet star.

 

[KRB52]

My first thought was, "hmmm...what does a heat detector do?...Just what does a heat detector do." Most of the time, I see those in office or commercial buildings.

 

[cowboyjosh]

Any old fire bells in the house? I remember going to a old *** Catholic School growing up and they had the exact heat detectors in all the classrooms and from what I remember the fire bells were 120 or 240 volt systems, different then what we obviously have today. The only thing the system did was trip, ring the fire bells. They obviously were only local alarms and didn't summon the Fire Department or anything.

Take it down, meter any wires attached.

 

[LS6 Tommy]

That's definitely an old Simplex-Grinnell 4255-1 heat detector. IIRC, they are Electro-pneumatic and are both rate-of-rise & fixed temp in one unit. They're also a one-time use device. I can't count how many of those I 've seen torn out in the last 15 years...

Tommy

 

[plow]

^^^Yep.^^^^


LS6, Are you in Fire protection?


I work here.

http://firetechsystems.com/

 

[6768rogues]

Some heat detectors are rate of rise and some are fixed temperature. Rate of rise is triggered by the temp rising a determined number of degrees in a certain time frame. They work well in areas with widely varying temps, such as under an outdoor gas canopy. Fixed temp have something that melts or fuses at a specific temperature. They work well in controlled environment conditions.
I would bet that yours is a fixed temp where something melts or fuses and a spring rings a bell.
Heat detectors are not life safety devices and smoke detectors are life safety devices. Heat detectors are used in areas where smoke detectors would be prone to false alarms. Forget about those crappy old detectors and buy some modern smoke detectors, they might save your lives.

 

[Garage5.9]

It's a camera and it's been broadcasting to the Web for the last I years

 

[dowmace]

That's definitely an old Simplex-Grinnell 4255-1 heat detector. IIRC, they are Electro-pneumatic and are both rate-of-rise & fixed temp in one unit. They're also a one-time use device. I can't count how many of those I 've seen torn out in the last 15 years...

Tommy

Beat me to it.

This is also the same unit used inside Diebold safe alarms.

 

[BFBOB]

Obsolete. Modern heat detectors reset, can be tripped multiple times. Those oldies were time bombs. Bad enough if they trip and stay tripped - finding the tripped one on a loop of dozens or scores is enough to try anyone's patience. Worse, they could trip and then open up, but not be able to trip again. To the system it looks like it's ready, and no non destructive way to tell.
The last system like this I had the misfortune to work on required testing (to destruction, of course) 10 percent of the detectors each year. If any failed to trip, we would have had to replace them all. Against all advice from us techs, we had to replace the tested units with exactly the same model. Something about how the service contract had been written... fortunately they were still in production then.
Ahhhh, the bad ol' days.
In a home, the only appropriate use for heat detectors is in close proximity to a device that could produce dangerous heat levels without smoke: furnace, water heater, maybe fireplace. Even then, they should only be used to supplement smoke detectors. People killed in fires are very seldom burned to death; it's the smoke that kills them, sometimes without even waking them up.
Heat detectors are also appropriate in areas that would be subject to false alarms from dust or moisture but still need fire detection - garages, washrooms, kitchens.

And, yeah, others beat me to much of this. Just couldn't resist.

 

[LS6 Tommy]

^^^Yep.^^^^


LS6, Are you in Fire protection?


I work here.

http://firetechsystems.com/

Nope. Facilities Maintenance Management for the last 18 or so years.

Tommy

 

[Cameronl]

Wow, some great info here. Thanks, guys.

Just to recap: Yes, I have smoke and CO detectors throughout the house.
There are two of these heat detectors; one in the living room (fireplace) and one in the bedroom. Don't know why one in the bedroom, but because it's been said that they tend to be used where there's a likelihood of false smoke alarms, I am reminded of the joke:

Q. Do you smoke after ***?
A. I don't know, I never looked.

I am not, nor have I ever, relied on these things, mainly because I didn't know anything about them. I'll just leave them be, I guess.