Stoker Low Temp Shutdown Switch

Looking for some direction.
I've yet to light my Koker for the first time so I've got a lot to learn and this site is making that easier to do.
One thing I have learned recently is that a power outage of more than about about 15 minutes may cause my direct vent furnace to go out. Once power is restored, my stoker will be busy pushing coal into my ash bucket until I get home from work. I'd like to prevent that from happening by installing a Thermodisc 60T snap-action low temp control switch in the vent pipe above the direct vent blower. My problem is I have been unable to locate a vendor to buy the switch from.
Question: where have you guys been finding these switches?
-Len

Just do a google search on SNAP SWITCH or THERMAL SNAP SWITCH, many companies sell these, probably an 80-100 degree, Close on Rising Temp (or open on falling temp). Probably around $20-30

Just get one rating for 110VAC, probably 1-5 amps would be plenty.

basically like this:

http://www.thermodisc.com/

My previous design.

Flue Temperature Sensor Interlock Device

Been there done that.
I've found quite a bit of information on the Therm-O-Disc thermal snap switch, but have yet to find anyone that will sell me one. I've "googled" this from every angle I can think of but haven't come up with a source yet.

Check out pellet stove and corn stove dealers. Most of these stoves from just about any mfg. use the thermo disc switches for proof of fire.

Outstanding Rick!
Thank you all very much.
I'll see what I can do with this.
-Len

http://www.grainger.com/product/2E245?BaseItem=2E247

WEll this session will not last so once on the web page search for 2E247
if you want something a little hotter use the 2E245

about 10 bucks and freight

Thank you Sting.
That looks exactly like what I need.
I'll follow up with Grainger.
You guys are are a wealth of knowledge, that's for sure!
-Len

I forgot where I got mine, I think it was a Solar or Woodstove website.? It know it was around $25, need to hook it up for this winter, only had one mishap of a full ash pan of coal.

Thanks to you guys I think I've got what I need.
I'm going to go to Grainger and buy one of two switches:

http://www.white-rodgers.com/wrdhom/pdfs/06_Cat_p ... pg0091.pdf
or
http://www.white-rodgers.com/wrdhom/pdfs/06_Cat_p ... pg0090.pdf

I'll probably go with the fixed 90 deg-110 deg switch.
I'm going to wait until I have a chance to run the furnace before I make a final decision. I want to measure some temperatures while it's running. I've got a thermometer on order and winter will probably be here before ya know it.
-Len

What about on a boiler? I have a friend that's thinking of something like this for his Keystoker and wants to put it on the exhaust pipe but I think that would get far too hot during operation. Any ideas?

Freddy

My boiler has the 90- 110 version of this switch in the upper smoke chamber - I monitor that.

Under HARD burn I see surface temperatures exceeding 375 - occasional spikes 10% more -- the switch lasts fine in that environment.

But I will report that early on --- to fool it and get fuel to a new fire --- I would hit it with my propane torch so it would see 110 a bit sooner -- once I hit it too hard and it didn't like that. Grainger had me a new one the next day

Kind Regards
Sting

Sting wrote:temperatures exceeding 375 - occasional spikes 10% more -- the switch lasts fine in that environment.

Oh, neato! I'll tell him. I thought that a bypass switch would be needed to get things up to temp, but a (gentle) propane seems like a good idea.

it really doesn't take much of a kindling fire and combustion air to get the snap switch to register and to close

At least in my baby boiler

but after the last debacle with my propane torch on the snap switch ( three seasons past now) --- well I leaned to be patient another 35 seconds or so for it to heat up on its own.

Yeah -- it don't take to many 15 dollar mistakes to catch my attention!!!

Len, keep in mind that with a mechanical vent furnace/stove there is a WMO or other venting safety switch which will generally trigger in a power outage of more than a minute or two, which will prevent the stove from feeding when the power comes back on. The posts you've seen in other threads about adding a low temp cutoff switch is typically for chimney vented stoves where there is no venting safety switch installed.

My keystoker is a direct vent and the safety interlock doesn't trip out on power outage. The Direct Vent safety plume switch has never tripped. I think if there is a blockage or the DV fails and it keeps stokings, the gases/ashes get out the hole to the sensor, it may trip. That is the one I have had problems with the coal continuing to be pushed after flame out.