So I got a thermocouple error on my Quadrafire 1200i pellet stove. When I was taking it out of the ceramic tube the twisted end busted off. Probably had enough of 7 years worth of heat cycles. I had nothing to loose so I cut off some of the sheath and twisted a new section. I then tried some solder and my stainless glass soldering iron on it, no dice wouldn't get hot enough. But I decided to measure the mV with a lighter and it got to 10mv with just barely any solder sticking to it. But I didn't trust it, so I hit it with my little mig welder and some steel wire. I don't know how to weld very well so the outcome was not very pretty and it doesn't look like it penatrated one of the wires very much. I decided to hook it back up and well it's working and measures 28mV when the stove is hot. I am not sure how good my weld is going to hold up and not sure how many more trimmings and if it would start changing the mV the shorter it gets. Got me looking and they sure do want a bunch of money for new ones. Anyone know where to get one that is rated the same and is long enough? Just thinking pellet stoves cant be the only thing using themocouples, anyone know another source?
Welded my thermocouple. It works, but want to find a generic replacement
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silverfox103
Feeling the Heat
I think I would replace it with one from Quadrafire. You just got 7 years out of the one you had.
Tom C.
Tom C.
Jaymaine34
Burning Hunk
- Jan 5, 2013
- 247
Haven't seen another option and I did look ! I know they are pricey but like silverfox said 7 years is pretty good ! I went with the Quad one as a spare .
FYI. Had a buddy of mine do the samething you did 3 years ago and it's still running fine ! He bought his stove used after seeing mine in action bought it for 400 because it wouldn't run and we took it all apart and cleaned it from the bottom up . The only thing we he has replaced on it 4 yrs is gaskets ( all homemade ) he always jokes if he needs a part he can always harvest it from one of mine ! Also his weld was pretty ugly also !
FYI. Had a buddy of mine do the samething you did 3 years ago and it's still running fine ! He bought his stove used after seeing mine in action bought it for 400 because it wouldn't run and we took it all apart and cleaned it from the bottom up . The only thing we he has replaced on it 4 yrs is gaskets ( all homemade ) he always jokes if he needs a part he can always harvest it from one of mine ! Also his weld was pretty ugly also !
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Harvey Schneider
Minister of Fire
Welding thermocouples isn't that difficult. The one thing that is important is not to add any other metals to the wires.The typical way to do it is to make one tight twist of the wires to hold them together and then arc against a graphite block with a small depression in it. The wires are connected together and tied to the hot electrode and the graphite block is tied to the return. What you want to aim for is a small bead at the tip with no other parts of the thermocouple wire touching.
this may help:
http://www.instructables.com/id/Making-A-Thermocouple/
A mechanical bond made by just twisting the wires tightly together will work, but it is more prone to fail due to exposure to gases from the fire.
this may help:
http://www.instructables.com/id/Making-A-Thermocouple/
A mechanical bond made by just twisting the wires tightly together will work, but it is more prone to fail due to exposure to gases from the fire.
Jaymaine34
Burning Hunk
- Jan 5, 2013
- 247
Harvey Schneider
Minister of Fire
By the way, If it is a type K thermocouple, you can get a welded but unterminated (bare wire ends) thermocouple on ebay for about $5
Thanks, tonight looking I thought I had narrowed it down to a type K looking at the charts. Just couldn't find anything as think, I was guessing 14 gauge going off of memory last night when welding. I'll look on ebay, not as critical tonight as it's still working fine. Last night I was a little flustered, and didn't really expect to see it working again tonight. I guess that weld isn't really going anywhere. I might hit you up for a link if I can't find what it on ebay, I did a quick search and see mostly test probes, nothing as heavy duty or thick of gauge. Thanks for the info though.
I used plain steel wire on my mig and it seems to be working fine so far. Only on second night so who knows. I know it would be best your way and that's the right way, but hey in a pinch it seems to work with steel wire on my welder. When looking at the charts tonight, I saw type K had roughly the temp/mv values and it is made of Chromel-Alumel, guessing I was probably lucky to get the steel wire to fuse to it. It sure didn't want to stick, but I've never welded small wire and was half guessing on my welders amperage and wire feed setting.
Having same issue on my 1100i , regular solder doesn't work what was your final fix? Or is it still working? $112.00 is what they want for mine around here. Also I'm curious how your stove acted with it broken just to compare my issues, some say that fixing the thermocouple wire won't fix my stove that I need a control box.
Everything you ever wanted to know about thermocouples.
http://www.advindsys.com/ApNotes/tcfundamentals.pdf
And here are the tables that tell you the voltages they generate at different temperatures
http://www.pyromation.com/Downloads/Data/temperature-tables.pdf
http://www.advindsys.com/ApNotes/tcfundamentals.pdf
And here are the tables that tell you the voltages they generate at different temperatures
http://www.pyromation.com/Downloads/Data/temperature-tables.pdf
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IIRC
The Quads ECM is somewhat fussy about the mv reading.
I would bite the bullet and get a factory unit.
Our 1000 uses the same TC I think, and it broke the same way a while back.
Good luck
The Quads ECM is somewhat fussy about the mv reading.
I would bite the bullet and get a factory unit.
Our 1000 uses the same TC I think, and it broke the same way a while back.
Good luck
woodmakesheat
Feeling the Heat
I was going to post similar. I have a large capacitor that I charge to some relatively low voltage, say 12V (basically you connect a power supply or 12V battery to the +/- terminals of the capacitor for those unfamiliar), then have a wire with an alligator clip connected to one terminal of the capacitor that I use to hold the two thermocouple wires side-by-side (touching each other.) On the other terminal of the capacitor I use a motor brush (easiest way to find a block of graphite with a wire attached to it for connection) and quickly "spark" the ends of the thermocouple wire pair against the graphite block. If all goes well, you'll get a nice ball on the end that looks like it did before it broke. I often have to cut and re-weld until I get a clean ball connection. I then separate the wires so they only touch at the weld.
What does somewhat fussy mean?
The service manual only states that the thermocouple may make up to 30mv when the stove is running. When it makes 2.5mv the green light in the control box comes on and at 12.1mv the red light comes on. Looking at the thermocouple picture in the manual shows a red and yellow wire which are the colors for K thermocouple wire. Looks like a inexpensive way to manufacture an analog input to the control board to control the pellet feed .I would think any K thermocouple would work.
Harvey Schneider
Minister of Fire
My mig welded original thermocouple is still going strong, knock on wood. I can't recall the symptoms when I found out it was bad. I do recall after working on it the original twisted end had become so brittle it all broke off. I trimmed it back and re-twisted it a bit and welded the end. I think I was somewhat lucky the weld actually took to the disimilar metals, so it's kind of a barnyard fix. I ended up ordering a cheapo $5 one off of ebay for when this one finally goes. That terminal block that the wires connect to below the logic board are about the cheapest thing I have seen, I remember when I re-attached the wires, the screws didn't go in correctly as they were half stripped from the factory. Can't wait till I have to fix that.
That's some pretty cool info, was wondering what made it so easy, I couldn't for the life of me imagine where/how to weld it using a chunk of graphite. Guessing you wouldn't want to pre-twist the ends of the thermocouple wires or it might arc before touching the graphite?
Harvey Schneider
Minister of Fire
You twist the leads together and arc the pair of them against the graphite. Then you untwist the leads leaving only the bead as the point of contact.
Incidentally if you are in a real bind, you can get a thermocouple to function for a while with just a twist and no weld. Keep the twisted portion short and very tightly twisted. You may have to trim off the damaged ends of the tc wire before you twist the leads together.
woodmakesheat
Feeling the Heat
Yes, that was the only issue I had with the video you posted, other than that it was "spot" on.
Thanks,bought new one, started stove manually and after it got warm enough the green light came on then red. So that issue us resolved. Thanks again.
Bought one of these for a dollar on fleabay. Makes millivolts just fine with a heat gun. Need to try it on the stove when it gets cold enough.
(broken link removed to http://www.ebay.com/itm/screw-high-temperature-thermocouple-k-type-6mm-thread-probe-sensor-1meter-3-3ft-/111546882095?tfrom=141500904133&tpos=top&ttype=price&talgo=undefined)
(broken link removed to http://www.ebay.com/itm/screw-high-temperature-thermocouple-k-type-6mm-thread-probe-sensor-1meter-3-3ft-/111546882095?tfrom=141500904133&tpos=top&ttype=price&talgo=undefined)
Harvey Schneider
Minister of Fire
You couldn't buy the materials for that price, and they pay the shipping.
For a stove, you don't need a precision, calibrated thermocouple. This should do just fine. If the life of it is less than ten years, you can certainly afford to replace it.
The only thing that seems questionable, it the 6mm screw end. Will that match the thread on your stove?
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