I installed a flu probe late in the season. When I start a cold stove and want to get the stove hot fast, the flu temps will rise up to the red zone around 1000 + f before even the stove gets to 600f. Nothing is turning orange and this is an internal temp, so I'm sure this is ok. How high does your stove pipe go into the red? I know cast iron (which is what I have) takes longer to heat compared to a steel stove.
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Backwoods said:
I don't like to go over 900 I get worried at the point. 1000 is really pushing the limit of stove pipe it is not intended to burn that hot for long without failure. It does not need to turn red just cause stress failure from internal heat.
Pete
Well I run 500 to 600 surface temp on single wall on startup all the time, I think you guys are worrying about nothing, 1000 degrees internal is no where near glowing.
So my question was, is it normal getting slightly into the red with a probe thermo during a cold start, waiting for the stove to get up to temp. Before getting the probe, I run the stove to 600f then start shutting it down. This is what I still do, except probe is reading 1000f+. I just want to see if this is normal and if this is what others are seeing. . I'm not really concerned with high flu temps, just watching the fire is all I really need.
WES999
Minister of Fire
I like to keep the flu temps under 900 °F . The manufactures recommended continuous operating temperature is 1000 °F .
Also you are sending a lot of heat up the chimney. The stove would probably heat up quicker if you start
closing the air in small increments when the flue temp reaches 900 °F .
Also you are sending a lot of heat up the chimney. The stove would probably heat up quicker if you start
closing the air in small increments when the flue temp reaches 900 °F .
HotCoals
Minister of Fire
I wonder when flue temps get much over 1000f if secondary flame can happen higher up in the flue?
Could be how some chimney fires start..I dunno.
I rarely see 400 surface temp 18" up..on start up.
Could be how some chimney fires start..I dunno.
I rarely see 400 surface temp 18" up..on start up.
certified106
Minister of Fire
I have a flue probe and I think I might have seen 700° once this year. For the most part I keep my temps 600° or under and have no problems whatsoever. I think it's all a matter of how soon you start cutting the air back. For the most part the only temperature reading I look at when getting a load going is the flue probe and on a full load I run it up to 600 and then start cutting it back to keep it there until the load is going good at which point I shut it all the way down and it usually settles in around 500° for the hottest part of the burn and tapers off from there.
Todd
Minister of Fire
Is it a condar flue probe? There's been some tests here comparing them with a more accurate thermocouple probe and we found the Condar to read a little on the high side especially at higher temps. I think the radiant heat off the pipe effects the coil spring on these probes and doesn't give a true accurate internal temp.
You have to have cresote to have a chimney fire, good burning practices will prevent that, I am not afraid to run my flue as high as is safe with no fear of any chimney fires what so ever.HotCoals said:
tfdchief
Minister of Fire
I like to keep mine at 800 or below, but I have seen 1000, even 1200 once, for just a short time, then back down. I don't think it hurts anything for short periods.
Treacherous
Minister of Fire
My Excel ICC has these numbers:
Allowable Flue Gas Temperatures
Max Continuous 650°C (1200°F)
Brief Forced Firing 925°C (1700°F)
Tested To 1150°C (2100°F)
http://www.icc-rsf.com/en/icc/technical-information-ultrablack
Allowable Flue Gas Temperatures
Max Continuous 650°C (1200°F)
Brief Forced Firing 925°C (1700°F)
Tested To 1150°C (2100°F)
http://www.icc-rsf.com/en/icc/technical-information-ultrablack
Is there a "rule of thumb" for converting outside temps on a double wall pipe to the internal temps that you would get with a probe thermometer?
I usually get the outside pipe temp (about 5" above the flue collar on the stove) up to about 240 before I start shutting the stove down in increments. I've read somewhere that for a rough estimate you double the outside temp (on a dbl wall pipe) to get the internal temp. Therefore, 240 outside would be about 480 inside...etc.
How accurate is this? Anyone out there with a probe thermometer and a magnetic outside pipe thermometer interested in checking this for me? Thanks!
I can't find a probe thermo at any of the local dealers...they actually give me kind of a funny look when I ask! "What would you need one of those for?"
I usually get the outside pipe temp (about 5" above the flue collar on the stove) up to about 240 before I start shutting the stove down in increments. I've read somewhere that for a rough estimate you double the outside temp (on a dbl wall pipe) to get the internal temp. Therefore, 240 outside would be about 480 inside...etc.
How accurate is this? Anyone out there with a probe thermometer and a magnetic outside pipe thermometer interested in checking this for me? Thanks!
I can't find a probe thermo at any of the local dealers...they actually give me kind of a funny look when I ask! "What would you need one of those for?"
jimbom
Combustion Analyzer
Yes. My flue thermometer probe temperature leads the stove top temperature on start up. Sounds normal for all installations. There is little mass in the flue gas and much more mass in the cast iron stove top. The flue gas should be much hotter on start up.Backwoods said:
I might consider, were I in your shoes, to start adjusting primary air at a lower stove top temp - say 400°F . Might still work and would save energy otherwise streaming up the flue, minimize thermal stress on the system, and slow temperature abetted corrosion of steel components.
Not accurate at all. I checked a while back and found that the surface temp of our double wall diminished with distance from the stove top. I think the best you are going to see is a relative reading. If you want a true indication of the flue gas temps in double-wall pipe a probe thermometer is required.
tfdchief
Minister of Fire
I find that the outside of the double wall is less than half of the probe flue temps. Between a third and a half.
Treacherous
Minister of Fire
Checking with my IR.... it shows 200 degrees on external surface and probe says around 500 degrees at 18 inches above stove.
WES999
Minister of Fire
The rule is that there is really is no rule. On a fast start up from cold, the inside temp can be close to 1000 °F, the outside may be only warm to the touch. (This is probably when flu temps are highest).
I can’t find a probe thermo at any of the local dealers…they actually give me kind of a funny look when I ask! “What would you need one of those for?â€
Probes are available from e-bay or http://www.condar.com/
An internal probe is really the only way to get a meaningful reading on double wall pipe.
HotCoals
Minister of Fire
How important is it to have a probe thermometer in the flu? I have an IR thermometer, and monitor my stove top temperatures. My flue is a double, 25 ' straight up, with the first 15' in the house. Also, if I decide that I need one, is it just a matter of drilling a hole and inserting it?
Treacherous
Minister of Fire
Ash Man said:
Easy install.
http://www.condar.com/probe_meters_dir4use_woodstoves.html
"Condar's FlueGard (3-39) Thermometer is designed for insertion into the stovepipe, with the end of the probe approximately centered inside the flue for accurate readings.
To install a FlueGard Thermometer, drill a ¼-inch hole in the flue pipe at least 18 inches above the top of the stove or furnace. For double-wall pipe, drill a ¼-inch hole in the outer wall, and a 3/16-inch hole through the inner wall. Position so the thermometer can be read easily at a glance. Slide the eyelet and magnet onto the stem of the thermometer; and insert into the hole.
When properly installed, the FlueGard accurately reads flue-gas temperatures, with an error margin less than 5%. If placed closer than 18-inches from the top of your stove or furnace, the thermometer will read slightly higher. Creosote on the stem of the thermometer will have little effect on the readings. When used on horizontal stovepipes, add 6% to temperature readings due to lower heat transfer. Before cleaning your flue pipe, remember to remove the thermometer."
WES999 said:
Thank you for all the replies.
I know that the flue probe thermo is readily available in the U.S. - but not so much in Canada.
I've got "cold feet" about having something shipped from the States. My last purchase was a seat cushion for an old car I am working on. I paid over the phone with my MC, and gave them clear directions to send it by "snail mail" via the US postal Service.
They didn't follow my directions, and sent it by United Parcel Service (I think that's the correct name!). UPS automatically transfers it to a brokerage firm at the border. Long story short, the $175 dollar cushion cost me close to $300
Easy install yes, but I found that even though I drilled a perfectly straight hole, the pipes will expand at different rates. When cool, probe is as straight as a nail, but when the pipes heat up, the outer expands one bit and the inner another, at different rates causing the thermo to tilt a bit. I have strong draft and maybe with an OAK, my flu is hot until I get the stove where I want it to begin shutdown. My stove usually runs perfect, stove top@ 650 and flu about 550f, 18"up with a probe. When I start cold, stove is cold and, stove pipe will heat up triple as fast as the stove, therefore high flu temps. If I gauge turning down the stove based on flu temp, I feel that the stove will lag, wood won't be at that sweet spot for shutdown. My jotul is very temperamental, as they are, and I need to be precise.
Treacherous
Minister of Fire
Maybe this shop in Langley would sell you one through the mail?
http://www.northweststoves.ca/accessories/condar-thermo.html
http://www.northweststoves.ca/accessories/condar-thermo.html
nelraq said:WES999 said:
Thank you for all the replies.
I know that the flue probe thermo is readily available in the U.S. - but not so much in Canada.
I've got "cold feet" about having something shipped from the States. My last purchase was a seat cushion for an old car I am working on. I paid over the phone with my MC, and gave them clear directions to send it by "snail mail" via the US postal Service.
They didn't follow my directions, and sent it by United Parcel Service (I think that's the correct name!). UPS automatically transfers it to a brokerage firm at the border. Long story short, the $175 dollar cushion cost me close to $300
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