monitoring attic and fire

[Desert_AIP]

From reading the instructions, it seems these are mechanical.

From the instructions:

As the temperature rises, the air within the sealed chamber expands. Should the chamber air expand faster than it can escape through the cali- brated vent, the diaphragm is depressed, and the electrical contact closes the circuit.

This part will reset but the high temp limit is a one shot deal.

The fixed temperature element reacts to heat by re-sponding to a specific temperature setting (135oF or 194oF). The detection method is based on the spring action of a metal contact, held to the metal chamber by a fusible alloy. When the temperature reaches the alloy’s melting point, the metal contact will depress the diaphragm, causing the electrical contact to close the circuit.

I didn't get that from reading the spec sheets, but I think now that you pointed it out you are correct.
The distinct lack of power supply and current draw should have been a dead give away.

Who the heck knows what an "eutectic metal" is anyway...

Thanks!

 

[WayneW]

If 12VDC, what is the current draw?

These are simple open-circuit devices, therefore their current draw is normally zero. The contact ratings are the max current the device is capable of.

 

[v1rtu0s1ty]

So folks, how do we address the fire burning the wire that we used for the heat sensor? Should it be inside a metal conduit pipe? If so, looks like it would be very difficult to install a conduit from basement then passing through first floor, then second floor.

 

[apostolakisl]

I put regular smoke/heat detector in my attic. However, my attic has spray foam insulation on the underside of the roof deck so it is part of the "enevelope" of air that is the whole house. In other words, it never even gets to 90 degrees up there and the dust levels aren't really any different than elsewhere in the house.

 

[beelzerob]

So folks, how do we address the fire burning the wire that we used for the heat sensor? Should it be inside a metal conduit pipe? If so, looks like it would be very difficult to install a conduit from basement then passing through first floor, then second floor.

It's recommended to use firewire, specially rated for withstanding the flames long enough for your sensor to work. No conduit needed. You would otherwise also use an EOL resistor so that if the wire is cut or shorted, that would also be an alarm condition

 

[v1rtu0s1ty]

It's recommended to use firewire, specially rated for withstanding the flames long enough for your sensor to work. No conduit needed. You would otherwise also use an EOL resistor so that if the wire is cut or shorted, that would also be an alarm condition

Awesome!

By the way, I opened my ELK Keypad 2 days ago and I couldn't remember why I put/provisioned a firewire there. So there's a LAN and firewire cable waiting. Hmmm, I'll have to reread my 2006 thread. I'm pretty sure someone suggested to me to put a firewire cable there. Any ideas?

 

[JimS]

Who the heck knows what an "eutectic metal" is anyway...

Thanks!

Eutectic refers to alloys that melt at a single temperature as opposed to alloys that go from liquid to solid over a range of temperatures. 63/37 tin lead solder is Eutectic. 60/40 solder is not and has a "plastic" region - a small range of temperatures where it is partly liquid and partly solid. My guess is they use eutectic elements to make sure they melt at a precise temperature.


http://en.wikipedia.org/wiki/Eutectic_system

 

[paw500]

For mounting heat detectors in finished rooms, are there also similar limitations that apply to mounting locations for smoke detectors (such as not within 4 inches of a corner/wall/ceiling)?

For unfinished spaces, should the detector be mounted on the 2" edge or the 10" side of a 2x10 joist or rafter?

 

[Del91574]

Finished spaces would technically be best in the center of the protected area up to the typical 30' radius most heat detectors cover.

In an asthetically perfect world, that doesn't work, so I try to go close to the area of concern if it's an appliance etc. without exceeding the detector's rating.

In an unfinished space, exposed joist, would be installed on the 2" edge. In an attic, there's variables, including the collar ties (if present) and distance to the ridge.