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Flue pipe temperature

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by higginscl, Nov 5, 2013.

  1. higginscl

    higginscl Member

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    So im posting this in the hearth room because my furnace is basicly like a wood stove with a metal cabinet around it. Its a US Stove company wood/ coal furnace. My question is what should I be running for temp on the outside of the single wall pipe. The setup is 6 ft of 6 inch single wall with two 90s into a masonry chimney lined with 25 ft of 6 inch stainless insulated liner and 5 ft of class A out the roof (some jackwagon knocked the chimney down just below the roof line so that was interesting making that transition.) I get killer draft with this setup and dont want to over fire so I havnt been pushing it too hard but I can still get it to 80 in the house in about 3 hours. Here are some pics of the furnace.

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    Last edited: Nov 5, 2013

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  2. Joful

    Joful Minister of Fire

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    The subject of outside vs. inside flue temps on single-wall pipe has been debated many times here, and several tests have indicated that the inside flue temps are very close to double the outside flue temps, as measured on single wall connector pipe. Knowing that, and reading up on the maximum sustainable flue gas temperature permitted for your chimney / liner, will give your answer. A common max operating temperature for liners is 1000F, meaning you don't want to see more than 500F continuous on the outside of your single-wall pipe, anywhere close to the liner.

    My pipe exterior runs around 200F, when the stove is cruising.
    Redcloud5400 likes this.
  3. higginscl

    higginscl Member

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    Thanks joful I have been reading around 250 to 300 with my IR gun and wanted to make sure it wasnt too low. The firebox is huge on this thing so maybe hotter is better?
  4. Joful

    Joful Minister of Fire

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    Yeah, and I think it's normal for a catalytic stove to have a lower flue temp than an EPA-exempt stove.
  5. Backwoods Savage

    Backwoods Savage Minister of Fire

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    Sounds like you are doing fine. Just remember that all chimneys still need heat in them in order to keep that good draft and not cake up. On our horizontal we aim for 400-500 to engage the cat. Once the cat is engaged, the flue temperatures drop to between 300-400 in winter months.
  6. Joful

    Joful Minister of Fire

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    Backwoods, just for clarity, are you measuring external or probe temps?
  7. HotCoals

    HotCoals Minister of Fire

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    I'm curious also.
    I'm like you ..when cruising I'm at 200-250f outside of the single wall.
  8. blades

    blades Minister of Fire

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    Hi , you got a wood eating monster there ( i have one also) when I was using it I tried to keep surface temp on the single wall under 500. Best I could ever achieve was about a 4 hour usable heat cycle. You likely will have to add a barometric damper to get a handel on that draft. The units tend to runaway on ya otherwise. Keep an eye on that automatic damper they like to stick mostly wide open. I never was fully comfortable to have it running and leave for the day. Never trusted it. Which model is yours.
  9. Backwoods Savage

    Backwoods Savage Minister of Fire

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    External single wall. One thing to keep in mind is that our readings will be a bit different. That is because if a flue goes vertical, vs one that goes horizontal, the only way you would get the same readings would be with a probe. Remember that heat does rise and with a horizontal pipe, the hottest part will be the top, and, of course, that is where we are measuring the temperature. I wish I could tell you how much difference there is but without some way to duplicate, I can not do it. I would suppose the best way would be to attempt to have two stoves ; both with probes and both with external gauges and then keep some records to compare. I would say one would need perhaps 20 different checks and then take an average and one could come close. But, it would take a lab or a manufacture to do some testing like that.

    EDIT: Like HotCoals, we do see a lot of temperatures below 300 but when in mid-winter, we usually are adding wood a whole lot sooner than during this time of the year. Now if I remember, I will try to write down temperatures this winter so I have record on paper rather than my failing memory. Dang, this is perhaps the worst of growing older; the memory banks seem to wear out.
    sappy and Joful like this.
  10. Log farmer

    Log farmer New Member

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    Hey backwoods, how far away is your thermometer from the stove? Mine is located about 18" above the stove (keystone) and mine ranges from 300* air set at .5 and 400* set at 1! And is single wall pipe.
  11. Joful

    Joful Minister of Fire

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    On a recent trip overseas, I was waiting in line to be processed by US security with a very friendly retired couple. We got to talking about several things, since the line was very long, including some of the yachts they had owned over their years. The man mentioned once or twice during this conversation that he had memory troubles, due to a head injury, but seemed so sharp that I didn't really think anything of it.

    At one point, the man was telling me about his favorite boat, which was actually a little insignificant Hobie Cat. He went thru the fun stuff they did with that boat, and places they took it, having much more fun with it than any of their larger yachts. At one point his wife said, "we never owned a Hobie, honey." His response was, "gee... thanks for ruining the memory for me. I really enjoyed that one."
  12. Backwoods Savage

    Backwoods Savage Minister of Fire

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    Just measured it and it is 8" from the collar. I do remember trying it at varying distances and this is where we decided at that time to put it. But we're not really fussy as it can get moved, like when you wipe dust off it may not get put back exactly the same spot but will be close.
  13. Backwoods Savage

    Backwoods Savage Minister of Fire

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    And yesterday I was at Home Cheapo and just about the time I was going to get in the car something came to mind that I had to call my wife. So, my mistake. I got in the car before pulling out my phone. Dialed the number then suddenly thought, "What was I going to ask her?" She answered the phone but even right now I have no idea why I called.... Disgusting at times; funny most of the time though.
    PapaDave likes this.
  14. higginscl

    higginscl Member

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    Its a 1602r I actually filled mine up half way yesterday with some oak and ash (maybe 6 large splits) on a hot coal bed at 5 pm and it was still putting out heat by morning. I figured out that if I shut the combustion fan off and close the flap on it, as well as close the air control on the ash door all the way down it cruises nicely at 450 on the firebox and 240 on the outside of the single wall without eating me out of house and home.
  15. Backwoods Savage

    Backwoods Savage Minister of Fire

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    Higginscl, I'd for sure save that ash until January! It is very rare here for us to put in any oak until usually around the 10th of January each year. That is when the real cold normally sets in around here. However, as we all know, our winters have been far from normal for several years now.
  16. Joful

    Joful Minister of Fire

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    I'm so OCD that I must use the wood in the order it was split and stacked. FIFO. I have a problem.
    PapaDave likes this.
  17. higginscl

    higginscl Member

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    I know I need to save the hardwoods for later in the season but I wanted to try a load of good wood to see how it performed. I work odd hours so I need to know how to tell the wife to load it when im not here. I have plenty of ash so a few pieces wont break me. As for the oak I just couldnt resist throwing a couple on (finally got to year 4 :)).
    PapaDave and Backwoods Savage like this.
  18. sappy

    sappy Member

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    I have a double wall pipe. The temp is about 18 inches from the bottom of the vertical pipe.
    When it is going well it cruises aroind 190 to 200. Now with double wall I have foind that you need to add around 100 degrees to that figure. Now it is like 290 to 300 on a single wall.
    We generally clean once a year and gray lite fluffy to some black soot.​
  19. higginscl

    higginscl Member

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    Thanks sappy. Sounds like im right on track with temps. Now if I can just talk the FIL in to checking his out and not just guessing at it or just plain not caring. After looking at his last Christmas I am very cautious with everything I do. He had something like a half inch of soot built up on the inside of the barometric damper and I told him he should think about cleaning it. His response was "yeah I know ill PROBABLY clean it this spring" !!! He burns stuff he splits in the fall:(
  20. Woodman

    Woodman New Member

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    Ok I am a first year wood burner. I am using the U.S. stove model 1537g. I hooked mine up as ether stand alone or in conjunction with my gas furnace. So far I have only used wood cause I shut the gas furnace off. we have had a very cold November and so far December here in Wisconsin. As far as I can see it looks like I will not need any gas to heat my home this year. I will however need about 4.5 cords of wood, thank god I split 15 cords this past spring with my neighbors. I damper back my flue every night so I get about a 9 hour burn. My flue temps over night never get above 250 outside temp on the 6 inch flue pipe. my day time flue temp runs just under 300. my home stays at 70 deg. or so in the day time and about 62 over night.

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