Flue Temp

Flue Temp

PostBy: tcalo On: Mon Dec 19, 2011 10:49 pm

I have a Coal Chubby stove with about 6 feet of single wall black pipe out the back of the stove and straight up into the support box in the ceiling. My old stainless steel chimney was only 4' above the roof and did not clear the peak, way to short. I was having issues with smoke in my house on windy days. I recently had a new insulated double wall stainless steel chimney installed. My chimney is now 10' above where it exits the roof and clearing the peak by 3 feet. It's been working great! There's a noticable improvement in my draft and I haven't had any issues with smoke...but my flue temp seems low. I recently picked up a magnetic thermometer for my flue pipe to keep an eye on the temp. It's been staying around 225* with stove temps around 550*. Flue temp rarely goes above 225*, often times is below the 225* mark. I've run my stove with the mpd fully open to try to raise the flue temp, but there isn't much of a difference. Haven't had a temp gauge on the flue with the old chimney, but it seemed to have higher temps. I burn wood during the day and supplement with coal at night so my concern is creosote buildup with these low temps. I have a barometric damper on my flue, but close it off when burning wood. Could these low temps be from the added height of the new chimney? Not too concerned since the stove seems to run great. Any input would be appreciated...thanks!
tcalo
 
Hand Fed Coal Stove: Chubby Coal Stove
Coal Size/Type: Nut Anthracite

Re: Flue Temp

PostBy: McGiever On: Tue Dec 20, 2011 1:00 am

Results w/ magnetic thermometers are usually a crude approximation...especially w/ a flat magnet on a round pipe. I do have one magnet type I use on a flat location and I calibrate it w/ a infra-red laser type, I pick a spot and shoot it w/ laser, then adjust the needle after the magnetic one has stabilized...you wouldn't believe how much it was off. My adjustable magnetic is an older model...newer ones may not be able to be adjusted. ;)

A inserted bi-metallic probe type is hands down the best way to go, if it is an accurate one and you have a hole to insert it in. :)

Another tidbit...At the same internal flue gas temperature, a black pipe's surface is less hot than a silver pipe's surface. Anything black radiates much better than the silver. :o
McGiever
 
Stoker Coal Boiler: AXEMAN-ANDERSON 130 "1959"
Hot Air Coal Stoker Stove: HARMAN MAGNUM
Hand Fed Coal Stove: RADIANT HOME AIR BLAST
Baseburners & Antiques: OUR GLENWOOD 111 BASEBURNER "1908"
Coal Size/Type: PEA / ANTHRACITE, NUT-STOVE / ANTHRACITE
Other Heating: Ground Source Heat Pump
Stove/Furnace Make: Hydro Heat /Mega Tek

Re: Flue Temp

PostBy: grumpy On: Tue Dec 20, 2011 1:28 am

Lower temps will cause creosote build up much faster. However I am told burning coal will dry it out and it should fall off the pipe and down into the ash pit. I burn wood and coal also, I try to burn the wood fires on the hot side to keep the chimney cleaner. I dont burn coal unless I can keep it going for a few days at least. Get a probe type and keep the temps above 300* If your getting 225* on the outside I'm sure its hotter on the inside.

But with that said, I have three and they all read different, go figure..
grumpy
 


Re: Flue Temp

PostBy: tcalo On: Tue Dec 20, 2011 9:42 am

Thanks for the replys. I try to burn my wood fires hot to keep the flue clean, just thought 225* was a bit low for single wall. Stay warm!
tcalo
 
Hand Fed Coal Stove: Chubby Coal Stove
Coal Size/Type: Nut Anthracite

Re: Flue Temp

PostBy: CapeCoaler On: Tue Dec 20, 2011 11:29 am

My magnetic thermo reads about 150* on the stove pipe...
Normal stove temps of 350*
CapeCoaler
 
Stoker Coal Boiler: want AA130
Hand Fed Coal Stove: DS Machine BS#4, Harman MKII, Hitzer 503,...
Coal Size/Type: Pea/Nut/Stove

Re: Flue Temp

PostBy: I'm On Fire On: Tue Dec 20, 2011 11:38 am

CapeCoaler wrote:My magnetic thermo reads about 150* on the stove pipe...
Normal stove temps of 350*


That's what mine reads too.

350° on top of the stove, about 260° at the stove outlet and 140-160° 24" up the pipe.
I'm On Fire
 
Hand Fed Coal Stove: DS Machines DS-1600 Hot Air Circulator

Re: Flue Temp

PostBy: tcalo On: Tue Dec 20, 2011 9:17 pm

I'm On Fire wrote:
CapeCoaler wrote:My magnetic thermo reads about 150* on the stove pipe...
Normal stove temps of 350*


That's what mine reads too.

350° on top of the stove, about 260° at the stove outlet and 140-160° 24" up the pipe.


Are those temps from burning coal or wood? I have my magnetic thermo about 18" above the stove pipe outlet. My 225* is from wood. The temps are much lower when I burn coal...about 150*.
tcalo
 
Hand Fed Coal Stove: Chubby Coal Stove
Coal Size/Type: Nut Anthracite

Re: Flue Temp

PostBy: CapeCoaler On: Tue Dec 20, 2011 10:49 pm

Coal...
Only when I crank the stove up to 500* will the pipe temps go above 200*...
Trying it with just the MPD...
It was so warm this "winter" that I pulled the Baro...
CapeCoaler
 
Stoker Coal Boiler: want AA130
Hand Fed Coal Stove: DS Machine BS#4, Harman MKII, Hitzer 503,...
Coal Size/Type: Pea/Nut/Stove

Re: Flue Temp

PostBy: tcalo On: Tue Dec 20, 2011 11:44 pm

How does pulling the baro help? Isn't the stoves draft regulated better with a baro...like when it's over drafting the baro will open?
tcalo
 
Hand Fed Coal Stove: Chubby Coal Stove
Coal Size/Type: Nut Anthracite

Re: Flue Temp

PostBy: CapeCoaler On: Tue Dec 20, 2011 11:50 pm

The DS has a bimetalic thermo air control...
So...
Some say a baro is not needed...
Going to find out for myself...
Just using a MPD and the bimetalic to control air flow...
So far so good...
It was really warm this "winter" and the baro was a draft parasite...
CapeCoaler
 
Stoker Coal Boiler: want AA130
Hand Fed Coal Stove: DS Machine BS#4, Harman MKII, Hitzer 503,...
Coal Size/Type: Pea/Nut/Stove

Re: Flue Temp

PostBy: tcalo On: Wed Dec 21, 2011 12:13 am

Interesting...good luck!

So I was splitting wood today with a maul. Hit a knot in the stump I was splitting and the stump drilled me in the shin...OUCH! I may have to switch to coal just to keep from getting injured. But the smell of burning wood is oh so good!
tcalo
 
Hand Fed Coal Stove: Chubby Coal Stove
Coal Size/Type: Nut Anthracite

Re: Flue Temp

PostBy: CapeCoaler On: Wed Dec 21, 2011 12:17 am

Put some wood chips on top of the coal...
Wood smell no splitting ;)
CapeCoaler
 
Stoker Coal Boiler: want AA130
Hand Fed Coal Stove: DS Machine BS#4, Harman MKII, Hitzer 503,...
Coal Size/Type: Pea/Nut/Stove

Re: Flue Temp

PostBy: I'm On Fire On: Wed Dec 21, 2011 3:28 pm

tcalo wrote:
I'm On Fire wrote:
CapeCoaler wrote:My magnetic thermo reads about 150* on the stove pipe...
Normal stove temps of 350*


That's what mine reads too.

350° on top of the stove, about 260° at the stove outlet and 140-160° 24" up the pipe.


Are those temps from burning coal or wood? I have my magnetic thermo about 18" above the stove pipe outlet. My 225* is from wood. The temps are much lower when I burn coal...about 150*.


Yes, with coal. I don't burn wood anymore; well, very little wood.
I'm On Fire
 
Hand Fed Coal Stove: DS Machines DS-1600 Hot Air Circulator