Flue is always hotter than stove?

  • Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.

    We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.

    We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil.
Status
Not open for further replies.

jasong

New Member
Oct 23, 2008
51
Palestine, Tx.
I have an Englander 13. My flue pipe is double wall and chimney is class A. My interior flue temperature is always at least 100 degrees higher than the stove. That's with secondaries or without. I have seen on the forum where everyone's stove is usually hotter than the flue when the secondaries start and the primary is turned down. It just seems like I'm loosing a lot of heat. Anyone else have this issue or have any solution?
 
Is the baffle in place and w/out damage?

I assume you know both thermometers are correct?

Are you using a probe or magnetic type? If it's a probe, then i wouldn't be surprised.

pen
 
Baffle is in its proper place and undamaged. I have two thermometers in the flue one is a condar probe the other is a thermocouple attached to a PID.
 
What temps are you seeing at both points? I'm wondering if it's possible that the thermocouple is not making good transfer contact with the stove top. Where is it located on the stove top?
 
I have had a problem with the thermocouple on the stove and haven't got that corrected but stove top temps were taken with ir gun. Right now the fire has died out the primary is shut all the way and stove at hottest point is 210 and internal flue is 234. usually with secondaries going primary shut down enough to maintain some flames on the wood the flue will be anywhere from 100 to 150 degrees hotter than the stove top.
 
The stove top is radiating heat off it. This is cooling it down. The flue isn't since it's class A and insulated. I notice a drop in temp when I turn the blower on.
 
Of course the flue is hotter, always will be. I would expect nothing different unless you have a cat stove. Consider that the stove is heating all air that passes through it to the stove temp and then the fire is adding even more heat. This is true all the time.

I have a condar probe meter for the flue and a surface meter for the stove top and there is not a time when the flue is colder than the stove.
 
It varies with the stove, the flue setup, wood being burned and stage of burn. Right now the Condar probe thermometer says 400 °F and the stove top reads 600 °F. This is with a couple very big splits burning. Stove was fueled about 90 min. ago.
 
Highbeam said:
Of course the flue is hotter, always will be. I would expect nothing different unless you have a cat stove. Consider that the stove is heating all air that passes through it to the stove temp and then the fire is adding even more heat. This is true all the time.

I have a condar probe meter for the flue and a surface meter for the stove top and there is not a time when the flue is colder than the stove.

I have stove top therm and flue probe. When stove is up to cruising the flue temp drops below the stove temp presumably because I have cut the airflow back.

edit - my flue is single wall
 
jasong said:
I have an Englander 13.

Just realised we have same stove. I loaded up at 7am this morning & haven't added anything more.

Now, at about 2.30pm, the flue probe isn't registering any temp and I can wrap my hands around the flue & feel a tiny bit of warmth.

Stove top is registering 200, for what it's worth. I can't leave my hands on the stove top for more than a moment.

As an aside...it's a nice sunny day and with 14,000 sq inches of window we're making a bit of solar gain :coolsmile:
 
Hmmm, I wonder why mine is always warmer. Of course you folks are talking about 200 degree stoves which only happens hours after the fire has gone out and I haven't looked at that point but if there was ever a time when the flue temp was cold it would be then. I'm impressed with the T6 at 600 stove top and 400 flue, can't imagine how that can be really. How can the stove be hotter than the fire or the heated gasses in the stove? Where is it getting the energy?

Maybe there is a flywheel effect where the fire can be squashed with water and the flue goes cold but the stove is still hot. We should only be considering actual running temps I would think.
 
Carinya's stove is the same model as mine but if my stove top was 200 my flue would a little higher not much. The hotter the stove or more active flames I have the larger the temperature difference. This would be true all the way down to a total cool down. It's like mine is letting more of the heat out of the stove into the flue than others with the same stove do.
 
Given the meticulous approach of Hearth community members......I kept meticulous notes of temps this afternoon.

Inside 66, outside 38

Loaded up with elm, top down start with door open.

10 minutes - door just about closed, realise air supply is closed :red: ..... open air supply

15 min - flue probe 900, stove top 750 start closing down air hellfire

20 m - flue 750, top 850 close air - aurora australis :)

25 m - flue 600, top 750 open air a bit

35 m - flue 400, top 600

1 hour - flue 400, top 600

I have found that the 13 and my retired Kent raise lower floor 1 degree each hour. (about 900 odd sq ft each floor with lower floor half set in hillside)
 
Her are mine.

Loaded up with 1 round 3 splits all oak on coals and door cracked.

10 min. stove 343, flue 507 shut door air open
15 min. stove 375, flue 510
18 min. stove 409, flue 600 close air 1/3 open
25 min. stove 426, flue 568 close air to 1/4" open
35 min. stove 528, flue 568
1 hour stove 583, flue 651
8 1/2 hour later stove 155, flue 182
 
Flue temps sound a little high and the stove temps seem low. Reconfirm that the baffle is correctly in place and sealing well in the back of the stove. From the temps described it sounds like hot gas is getting straight up the flue behind the baffle. Look for ways this could be happening. Check that the baffle has no cracks or gaps.
 
Highbeam said:
Hmmm, I wonder why mine is always warmer. Of course you folks are talking about 200 degree stoves which only happens hours after the fire has gone out and I haven't looked at that point but if there was ever a time when the flue temp was cold it would be then. I'm impressed with the T6 at 600 stove top and 400 flue, can't imagine how that can be really. How can the stove be hotter than the fire or the heated gasses in the stove? Where is it getting the energy?

Maybe there is a flywheel effect where the fire can be squashed with water and the flue goes cold but the stove is still hot. We should only be considering actual running temps I would think.

Im with you still on this Highbeam, even with the damper I installed my flue is still always hotter (450-500 top, 700-900 internal flue, sometimes 1000 for a while). I can find no way to change this and am of the belief that I cant!
 
Highbeam said:
Maybe there is a flywheel effect where the fire can be squashed with water and the flue goes cold but the stove is still hot. We should only be considering actual running temps I would think.

Would your idea of the flywheel effect extend for an hour or more ? BG & I seem to have the differential running for quite a while.....

A confusing item would be a stove top that is similar to a heat shield. I noticed on my daughter's Buck 80 that the stove top is a sheet above the firebox plate - it pumps heat out at the front of the stove . Her "stove top" temp would be lower than the actual firebox top.
 
Highbeam, what height is your probe off of the stove top? Mine is a bit high at 24" because I have a double-45 offset coming right off of the stove. Thinking about probes, this just occurred to me.
 
I have the same problem with hotter flue or same temp flue as stove. I have tried everything you can think of. What works for me now is a box fan place about 10-15ft from stove blowing at the flue. I have given up on everything else. Fespo
 
My probe is 15" above the stove top. I spoke with the tech guy at condar and he said that this is fine and readings will be nearly identical (higher if anything) to those from the normal 18" spec. I do have double wall pipe which if anything should give me lower temps on the probe meter.

I think that the soapstone is going to be an issue here too. I read the stove temps that you guys run and my stove never gets that hot but my fire is still a wood fire and just as hot.

I suppose it isn't a problem to have a hotter flue than stove, it seems to make sense that it would be that way.
 
carinya said:
Given the meticulous approach of Hearth community members......I kept meticulous notes of temps this afternoon.

Inside 66, outside 38

Loaded up with elm, top down start with door open.

10 minutes - door just about closed, realise air supply is closed :red: ..... open air supply

15 min - flue probe 900, stove top 750 start closing down air hellfire

20 m - flue 750, top 850 close air - aurora australis :)

25 m - flue 600, top 750 open air a bit

35 m - flue 400, top 600

1 hour - flue 400, top 600

I have found that the 13 and my retired Kent raise lower floor 1 degree each hour. (about 900 odd sq ft each floor with lower floor half set in hillside)

Wow, that's some high temps. How do you only burn 2 cords a year in OH?

RD
 
Motor7 said:
Wow, that's some high temps. How do you only burn 2 cords a year in OH?

RD

To be honest it's probably only a chord and a half....

House was built in 1984 and is well insulated. Living area has rear half (northside) built into hill with 14,000 sq inches of window facing south for good solar gain. House temperature is reasonably stable

Today I built a fire at 8am adding nothing until I stoked up another small one at 8pm for friends who were visiting.
 
Status
Not open for further replies.