Stove and flue temps too high?

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Sconnie Burner

Sconnie Burner

Feeling the Heat
Aug 23, 2014
488
Western Wi
Running a quadra fire 3100 step top at my friends house I'm renting from him. Wood is 2 yrs seasoned. Never had this problem last year, mainly because my wood was sub par I'm sure.

The stove is in the basement with an exterior stainless chimney running to about 3 ft above the peak on the gable end of a 2 story house. My pipe temp will creep upwards of 500 degress surface temp and stove hits 700-750 on reloads and hang there for a good hour or so even with stove closed to as far as factory will allow. I know the quads are built for the heat but this is with the secondary (tube) inlet half blocked and the primary blocked so when its closed all the way there is just a sliver of air coming in. I do leave it open a little more knowing this. Thats just a precationary step to shut down an over fire.

Problem is once it starts dropping I loose flame and end up with a bunch of coals as the air is shut down so far. Am I closing too fast (takes about 10 mins with good rolling flames) not allowing the off gassing to escape up the chimney some and forcing it all to burn really hot really fast in the stove? It seems all my wood turns to coal in about 2 hours from the secondaries burning it up as they go acrossed the top. A full load of 6 splits stacked fairly tight will pretty much hold their shape but be all coal with a little that has fallen off the ends with barely any flame unless I open the air back up. Seems like it is obviously overdrafting in these colder temps <20. Any suggestions greatly appreciated!
 
How does one measure the flue temps?

Do you think it's best to NOT leave the air intake valve fully open at all times?
 
oska said:
How does one measure the flue temps?

Do you think it's best to NOT leave the air intake valve fully open at all times?
Click to expand...

Either a magnetic stove thermometer for single wall stove pipe or a probe style thermometer for doublewall pipe.

No ... air intake generally should be open at start up and then progressively closed to achieve longer burns ... plus with a secondary burning stove it will burn cleaner and get more heat from the burn.
 
butbutbut I read elsewhere that keeping it open maximally will prevent the wood from smoldering and wasting all the precious wood gasses?

I was also informed that the wood burns just as quickly with the air port fully open as it does with just a smidgen open.

Is that just nonsense propaganda?
 
Keeping the air open will waste the wood gases right up the chimney. The only condition where that might be necessary is trying to get damp wood to burn. Wood is going to burn differently in a pure coal stove. The air supply was not intended for wood burning because it puts the air below the firebed. This is good for coal, not so good for wood as it tends to burn it up quickly and inefficiently.
 
Last edited:
begreen said:
Keeping the air open will waste the wood gases right up the chimney. The only condition where that might be necessary is trying to get damp wood to burn. Wood is going to burn differently in a pure coal stove. The air supply was not intended for wood burning because it puts the air below the firebed. This is good for coal, not so good for wood as it tends to burn it up quickly and inefficiently.
Click to expand...

Thank you for your reply, I really really appreciate your expertise on this subject :)
 
Last edited by a moderator:
A thermometer on the stove pipe is a useful instrument for burning safely. You don't want the fire to smolder, it should have a lazily active flame once it is going well and the air is turned down. The stove pipe (if single wall) should not get over 500::F.
 
And I believe most wood stoves can easily exceed that 500f if run with the air intake fully open all the time. It's not something I ever do or I believe it would either destroy the stove or burn the house down.

I've burned my whole life(41yeads old) and have learned more about fireplaces and burning since signing up here than in all those decades beforehand. But a lot of what I learned about the basics confirmed that I have always been on the right path.

That being said I'd never go without a stovepipe thermometer again. Cheap and easy.
 
Squisher said:
And I believe most wood stoves can easily exceed that 500f if run with the air intake fully open all the time. It's not something I ever do or I believe it would either destroy the stove or burn the house down.

I've burned my whole life(41yeads old) and have learned more about fireplaces and burning since signing up here than in all those decades beforehand. But a lot of what I learned about the basics confirmed that I have always been on the right path.

That being said I'd never go without a stovepipe thermometer again. Cheap and easy.
Click to expand...

How would that destroy your stove or burn the house down?
 
Overfiring the stove can warp components and/or cause cracks to develop. Too high flue temps will exceed the rating of the pipe. If the stove pipe dumps into a masonry chimney very high temps can cause wood that is touching the chimney to pyrolize which lowers it's ignition temperature. High temps also weaken mortar which further increases the risk of failure.

Is the chimney lined with clay or stainless steel?
 
Getting back to the OP, those temps seem a little high to me. The 3100 isn't a huge stove and running a 500 stove pipe temp will blow through wood pretty quickly I would think. I would aim more for 300-350. Have you done the dollar bill test on the door gasket?
 
What do you estimate the chimney length to be? Sounds like it could be pretty long. If you're having trouble controlling the burn even after limiting the air you may be a candidate for a key damper.
 
Sounds like every time I reload the 30-NC. Except that when all hell breaking loose is over you open the primary air a bit to keep the fire burning. 500 exterior pipe temp is 1,000 or so interior and on any of my stoves I see that when a fresh load is offgassing. Do what you are doing but let that puppy have a little air for the long burn.
 
So what temperature should the flue be, exactly - for the most efficient burn? (on a single pipe)?
 
Where exactly are you all measuring pipe temps? 12" above stove outlet? 18" above? What is the ideal place/location for measuring temp with a magnetic thermometer on single wall pipe?
 
oska said:
So what temperature should the flue be, exactly - for the most efficient burn? (on a single pipe)?
Click to expand...
For coal follow the manual's guidance.
 
I did a full reload and kept the flames lightly dancing while tunimg it down rather than waiting for a rolling inferno on the first step. Much better results! Might have been having a brain fart and was just waiting to long to start shutting down the air. Or just had a couple loads that offgassed really fast. I will bet the chimney is nice and clean after 2 loads that got that warm!

If I owned the place I would surely put in a key damper. He always burned wood that was on the wetter side (only c/s/s for a summer) so he never had overfire issues. Probably wouldn't believe me that it needs a damper unless I have him come over and see it for himself.
 
Sconnie Burner said:
I did a full reload and kept the flames lightly dancing while tunimg it down rather than waiting for a rolling inferno on the first step. Much better results!
Click to expand...
If you can control the fire then you're in good enough shape. See what happens as the temps drop.
 
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