stack temp rises when closing pipe damper

[tobaccogrower]

i insatlled a pipe damper on my tucker allagash when installing for piece of mind. the stove is a old insert converted to be free standing in my shop. chimney is 27.5 feet. 10 feet of single wall,45*, one foot, 45* then 17 feet of double wall. double is 7 inches and single is 6 inch.

i get such a good draft that the sound of air sucking into the holes in front of the door can be heard on the other side if the shop! i recently started messing around with the damper to adjust heat. after i get a good fire going i need to close the air down to about 1/4 shut. this keeps stack temp around 450* and stove top at 500. i have my thermometer 18 inches up and the damper is just below it.

if i have a well estableshed fire and a good bed of coals with air set at 1/4 to keep the 450 stack if i close the pipe damper almost all the way my stack temp will climb to 500-550. is this because im holding the heat in the stove better? maybe because im necking it down and the compressed gasses are hotter?

is 500* stack temp acceptable or should i try to avoid temps that high? i notice when im at or over 500* i smell the pipe paint(2 week old) another thing is after inital startup there is no smoke visable! when i check outside it dosnt even look like the stove is running!

 

[weezer4117]

i insatlled a pipe damper on my tucker allagash when installing for piece of mind. the stove is a old insert converted to be free standing in my shop. chimney is 27.5 feet. 10 feet of single wall,45*, one foot, 45* then 17 feet of double wall. double is 7 inches and single is 6 inch.

i get such a good draft that the sound of air sucking into the holes in front of the door can be heard on the other side if the shop! i recently started messing around with the damper to adjust heat. after i get a good fire going i need to close the air down to about 1/4 shut. this keeps stack temp around 450* and stove top at 500. i have my thermometer 18 inches up and the damper is just below it.

if i have a well estableshed fire and a good bed of coals with air set at 1/4 to keep the 450 stack if i close the pipe damper almost all the way my stack temp will climb to 500-550. is this because im holding the heat in the stove better? maybe because im necking it down and the compressed gasses are hotter?

is 500* stack temp acceptable or should i try to avoid temps that high? i notice when im at or over 500* i smell the pipe paint(2 week old) another thing is after inital startup there is no smoke visable! when i check outside it dosnt even look like the stove is running!

in order to reduce a strong draft you have to work the primary air and damper together. meaning if you reduce one then the other needs reduced as well. if you want to restrict air from leaving the stove then you have to restrict air from going in it!! as far as not seeing any smoke, that is good. less smoke= less buildup. the single wall pipe (when HOT) will smell for sometime and will eventually stop. typically my stove top temp and stack temp have around a 150*- 250* difference. if your stack temp is vertually the same temp as your stove then you are loosing ALOT of heat up the chimney. it is very important to maintain a good stack temp but it should not be as hot as your stovetop.....

 

[LLigetfa]

My guess is the laminar flow is disrupted by the key damper, bringing hotter gasses closer to the pipe surface where the thermometer is. The gasses tend to flow faster near the centre when laminar so near the surface it will be cooler.

http://en.wikipedia.org/wiki/Laminar_flow

 

[branchburner]

i have my thermometer 18 inches up and the damper is just below it.

It makes sense to me for the stack temp to be very high right around the damper, both just above and just below, where the flow is restricted (allowing the pipe to heat up).

I agree, maybe to try to run the stove at 600 and the stack around 400 instead of both at 500. What happens when you drop the air below 1/4? Still smoke-free?

This may be one of those instances where a heat reclaimer on the pipe makes sense.

 

[tobaccogrower]

id love to put a magic heat on it! problem was everyone on the site advised them at all cost because of buildup. my dad has been running the same one in his shop for 20 years.

i really cant get a accurate temp off the stove top because the whole stove has a 2 inch air jacket for the blower. thanks for the replies.

 

[branchburner]

id love to put a magic heat on it! problem was everyone on the site advised them at all cost because of buildup.

Well, everyone but Pook - LOL. Only way to know if you will get creosote is to find out firsthand. With a tall stack, I think you'd be sure to get some at the top by cooling the pipe, but enough to really matter?