Comparing Temps Between Flue Pipe and Stove Body

Comparing Temps Between Flue Pipe and Stove Body

PostBy: Lightning On: Sat Oct 26, 2013 11:01 am

I am running a hand fed furnace which functions quite closely to a hand fed stove so I thought this topic would fit well here. At the start of a new fire, my temperature difference between the flue pipe and furnace will run a difference of 50-60 degrees.. For example, the pipe will be around 150 and the furnace above the load door will be around 205.. What I find really interesting is that as I get a few days into a new fire, with all other variables being consistent (outside temp, draft pressure, indoor temp, primary and secondary combustion air ratio) my difference between the flue pipe and furnace will grow.. In the picture you see the furnace temp at 257 and the pipe temp at 162.. This is approaching a 100 degree difference.. and after even more time, the difference will go over 100 degrees..

My deduction on this is that after several days of starting a new fire, ash settles into all the nooks and crannies where primary combustion air was bypassing the coal bed, such as between gaps in firebricks and around grate frames. After this settling of ash, the primary air is forced to burn more efficiently.

Anyone have thought or comments?
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Lightning
 
Hand Fed Coal Furnace: Clayton 1537G
Coal Size/Type: Nut Size / White Ash

Re: Comparing Temps Between Flue Pipe and Stove Body

PostBy: freetown fred On: Sat Oct 26, 2013 11:59 am

Yep, stove body'll be hotter :clap: toothy It's a friggin bar-b-que thermo
freetown fred
 
Hand Fed Coal Stove: HITZER 50-93
Coal Size/Type: BLASCHAK Nut/Stove mix

Re: Comparing Temps Between Flue Pipe and Stove Body

PostBy: Lightning On: Sat Oct 26, 2013 12:10 pm

Yeah man!!! I love my BBQ thermometer!! It's wireless, I also carry it all over the house to monitor my furnace, It sits at my bedside at night. It even has alarms for when it's running hot or cold. It's my hero :lol:
Lightning
 
Hand Fed Coal Furnace: Clayton 1537G
Coal Size/Type: Nut Size / White Ash

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Re: Comparing Temps Between Flue Pipe and Stove Body

PostBy: franco b On: Sat Oct 26, 2013 12:22 pm

Degree of radiant heat from the coal as opposed to burning gasses make a difference.

Right now after starting Vigilant about 3 hours the pipe is 200 and the stove top 500. Measured about a foot above stove for the pipe.
franco b
 
Hand Fed Coal Stove: V ermont Castings 2310, Franco Belge 262
Baseburners & Antiques: Glenwood Modern Oak 114
Coal Size/Type: nut and pea

Re: Comparing Temps Between Flue Pipe and Stove Body

PostBy: Lightning On: Sat Oct 26, 2013 12:32 pm

franco b wrote:Degree of radiant heat from the coal as opposed to burning gasses make a difference.

Right now after starting Vigilant about 3 hours the pipe is 200 and the stove top 500. Measured about a foot above stove for the pipe.


I agree that would be the case thru a typical 12 hour burn cycle partner, but what about after say a week of starting a new fire? Do you see a bigger temp difference between stove and flue pipe? My reading is also about a foot after outlet and on top side of the pipe. :D
Lightning
 
Hand Fed Coal Furnace: Clayton 1537G
Coal Size/Type: Nut Size / White Ash

Re: Comparing Temps Between Flue Pipe and Stove Body

PostBy: franco b On: Sat Oct 26, 2013 3:39 pm

Franco Belge remains the same except late in the season when stack temp goes up a bit. I believe because fly ash begins to insulate the heat exchange passages that wrap around the stove. Very low stack temp.

Glenwood Modern Oak 114 stays the same about 100 degree difference.

Too early to tell with Vigilant.
franco b
 
Hand Fed Coal Stove: V ermont Castings 2310, Franco Belge 262
Baseburners & Antiques: Glenwood Modern Oak 114
Coal Size/Type: nut and pea

Re: Comparing Temps Between Flue Pipe and Stove Body

PostBy: Lightning On: Mon Nov 04, 2013 8:46 am

So now its about 12 days since I've fired up. My temperature difference started out around 50-60 degrees between the pipe and over the load door. Since then, the gap has widened gradually daily. This morning I'm seeing 105 degree difference.

Although, today is colder, my draft is stronger, my secondary air is closed a little more and I have the primary open a little more. Maybe I'm burning more efficiently with these conditions.
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Lightning
 
Hand Fed Coal Furnace: Clayton 1537G
Coal Size/Type: Nut Size / White Ash

Re: Comparing Temps Between Flue Pipe and Stove Body

PostBy: franco b On: Mon Nov 04, 2013 12:16 pm

Good to see you are shining light on the subject.

With burning hotter it's bound to be more efficient.
franco b
 
Hand Fed Coal Stove: V ermont Castings 2310, Franco Belge 262
Baseburners & Antiques: Glenwood Modern Oak 114
Coal Size/Type: nut and pea

Re: Comparing Temps Between Flue Pipe and Stove Body

PostBy: Lightning On: Mon Nov 04, 2013 3:00 pm

franco b wrote:Good to see you are shining light on the subject.

With burning hotter it's bound to be more efficient.

Thanks Franco,
I would have to agree that there is a point at which the most efficient burn is produced. Running hotter would loose heat up the chimney and running cooler would loose un burnt gases up the chimney.
Lightning
 
Hand Fed Coal Furnace: Clayton 1537G
Coal Size/Type: Nut Size / White Ash

Re: Comparing Temps Between Flue Pipe and Stove Body

PostBy: ddahlgren On: Fri Nov 08, 2013 8:40 am

Lightning wrote:
franco b wrote:Degree of radiant heat from the coal as opposed to burning gasses make a difference.

Right now after starting Vigilant about 3 hours the pipe is 200 and the stove top 500. Measured about a foot above stove for the pipe.


I agree that would be the case thru a typical 12 hour burn cycle partner, but what about after say a week of starting a new fire? Do you see a bigger temp difference between stove and flue pipe? My reading is also about a foot after outlet and on top side of the pipe. :D


A magnetic thermometer reads surface temps and about one half of what a probe does inserted into the stack pipe.
It has worked that way since I started a couple of years ago at least with a wood stove and no reason to think not the same on coal.
Others that run both have found exactly the same thing so maybe qualify how the temperatures are measured would make some sense.
ddahlgren
 
Hand Fed Coal Stove: Crane 404

Re: Comparing Temps Between Flue Pipe and Stove Body

PostBy: ddahlgren On: Fri Nov 08, 2013 8:41 am

Lightning wrote:
franco b wrote:Degree of radiant heat from the coal as opposed to burning gasses make a difference.

Right now after starting Vigilant about 3 hours the pipe is 200 and the stove top 500. Measured about a foot above stove for the pipe.


I agree that would be the case thru a typical 12 hour burn cycle partner, but what about after say a week of starting a new fire? Do you see a bigger temp difference between stove and flue pipe? My reading is also about a foot after outlet and on top side of the pipe. :D


A magnetic thermometer reads surface temps and about one half of what a probe does inserted into the stack pipe.
It has worked that way since I started a couple of years ago at least with a wood stove and no reason to think not the same on coal.
Others that run both have found exactly the same thing so maybe qualify how the temperatures are measured would make some sense.
ddahlgren
 
Hand Fed Coal Stove: Crane 404

Re: Comparing Temps Between Flue Pipe and Stove Body

PostBy: CoalisCoolxWarm On: Fri Nov 08, 2013 9:55 am

Looking at your Dwyer pic, is there a reason you didn't zero your manometer?
CoalisCoolxWarm
 
Stoker Coal Boiler: Keystoker KA6
Hand Fed Coal Furnace: old Sears rebuilt, bituminous
Coal Size/Type: Kittanning Seam, Stove size
Stove/Furnace Make: old handfired bituminous

Re: Comparing Temps Between Flue Pipe and Stove Body

PostBy: Lightning On: Fri Nov 08, 2013 12:01 pm

CoalisCoolxWarm wrote:Looking at your Dwyer pic, is there a reason you didn't zero your manometer?


Uh. ...What? It's reading the negative pressure in the flue pipe in the picture. :?
Lightning
 
Hand Fed Coal Furnace: Clayton 1537G
Coal Size/Type: Nut Size / White Ash

Re: Comparing Temps Between Flue Pipe and Stove Body

PostBy: Stanb999 On: Fri Nov 08, 2013 12:52 pm

Lightning wrote:
CoalisCoolxWarm wrote:Looking at your Dwyer pic, is there a reason you didn't zero your manometer?


Uh. ...What? It's reading the negative pressure in the flue pipe in the picture. :?



The whole inverted scale issue.
Stanb999
 
Stove/Furnace Make: Harmon
Stove/Furnace Model: Mark II

Re: Comparing Temps Between Flue Pipe and Stove Body

PostBy: Lightning On: Fri Nov 08, 2013 1:15 pm

Oh yeah lol right. It's hooked up backwards to read the negative value on the positive side of the scale. Sorry :lol:
Lightning
 
Hand Fed Coal Furnace: Clayton 1537G
Coal Size/Type: Nut Size / White Ash

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