Thermocouple symptoms.

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downtime

New Member
Hearth Supporter
Mar 5, 2007
13
TX
I have a Quad 1100i insert that starts without error but only runs 10 minutes and shuts off the auger and shuts down. Call light is still on. I can press reset button and the cycle starts again. We bought the house with the stove in it, so I'm sure no warranty exists. I downloaded an owners manual from Quad hoping for some answers. The manual says replace thermocouple and if that doesn't work check control box (see dealer of course.) I've found the thermocouple online for around $70 and don't want to waste the money if this doesn't fix the problem only to spend a couple hundred more to replace the control box. So that being said, do any of you think this is a thermocouple problem? If so, do you know of any cheaper places to get one? Anyone know how to test the control box?
 
Take the cover off the thermocouple very carefully. Check it for cracks or missing chunks. If the cover is damaged your thermocouple is toast. Check the two wires for the thermocouple near the bulb on the end. If either has a break in it, it is done.

Do you have a multimeter that can read DC voltage available to use? I can give you further instruction if you do.
 
Welp I am going to work so I will offer my extra advise briefly. I'm sure you want to figure this out ASAP.

Check if your thermocouple gets hooked to a terminal block under the control box. That's how a 1200i I worked on recently was. Set your meter to the lowest possible DC setting, should be 200 or 20. I use gator clips and clip one on each thermocouple wire (while still hooked up). You should get a reading off it when the fire gets going. 2.5mV is supposed to be the next sequence in the startup and then 12mV its it into the normal burn cycle.

If you don't get anything at all then its probably shot.
 
I'm getting more than I should if your numbers are correct. 6-7 mV on start and 55 mV when the fire is a full blaze. Not sure if that is good or bad. I'll probably call the local dealer and see if I can try a new t/c and perhaps bring it back if it doesn't fix it.
 
Yeah 55mV at full go is normal. I was just giving you the minimum readings for the control box to recognize the fire. Now that I think about I think they are supposed to top out at like 30mV but you probably have a pretty old one so who knows.

Do you have a clear control box in your unit or the old grey one?

Next thing I would check is the vacuum switch. As a simple test you can unplug the stove and then take the two wires off the switch and jumper them together. Then try running it as normal. If the stove works fine you have pinpointed the problem. Take the tube off and blow it out. Also take something small and try to clean out the hose barb welded to the auger tube.
 
I pulled the tube off and blew it out. Lots of dust. Ran stove and it worked as normal. The whole time I've had this problem only one of the LEDs on the control box would stay lit. After blowing out the tube both LEDs are lit. I figured this was the problem. But now when I disconnect the vacuum switch tube while running, both LEDs stay on. Any ideas?
 
If you leave the VAC tube off for a little while the stove should shut down because it thinks it lost vacuum. The vac switch just closes the circuit when there is a vacuum applied to it. Most of the Quad units, this will cut power to the auger when "open". With the stove off you can test the continuity between the two contacts on the switch (with a multimeter set on Ohms). You should get an "infinite" reading. If you get continuity with the stove off or the hose disconnected the vac switch must be stuck closed. Did you blow into the tube with the switch connected at all? This would damage it and the diaphragm could be blown out.
 
I know this is an old thread but the problem came back earlier this month. Checked all the things suggested above and once again all checked good. I then decided to "field calibrate" the control box with my thumb and middle finger. Thump, thump, thump.....both lights came on and all is back to normal. I might be shopping for a new control box soon. If anyone has a schematic, or knows where I can get one, I may be able to put my education to work and fix it myself.
 
Take it apart anyways, check for cracked solder or loose part. No body seems to be able to get control box schematics, proprietary I assume.
 
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