Harman XXV Venting

[Crab]

I am considering purchasing a XXV to be vented into an existing undamaged masonry chimney. The chimney is 7" X 7" terracotta lined approx. 25' tall. I plan to use the Harman 6" adapter connected to 4' of 6" black stovepipe, then 90 into a 8" thimble which connects to the 7 X 7 terracotta liner. Note:The terracotta chimney continues below the thimble 4' to a cleanout. I have had some draft issues with the old woodstove, will I have draft issues with the pellet? Has anyone tied into an existing setup such as mine? If I need a smaller SS liner as Harman's online manual suggests, I will stay with a woodstove. The chimney is in excellent shape..Thanks for any assistance...LA

 

[pjmac]

I installed my XXV last year and used the top adapter. From the adapter Approx. 3' of SS pipe and then a SS 90 and 4' into my masonary and tile lines chimney. From there I reducer to 4" SS pipe up 18'. I used all last winter and it operated great with no problems. When I cleaned the chimney this fall there was less than two cups of dust in my pipes.

 

[HarryBack]

I as well dont think you'll need to line the chimney, but I would suggest using seamless pipe, and RTV'ing the joints so they dont leak. Also, how are you connecting to the thimble? The right way to do this is to run a length of stovepipe inside it to where it terminates...usually a pretty tight fit, but it will ensure your pipe doesnt fall out...You'd be surprised how many folks just stuff the crimped 1-1/2" into the thimble and call it good....kinda scary. If you have an 8" ID thimble, then use 8" smokepipe inside....yea, it might be pretty hard to get the 8" pipe in the 8" thimble.

 

[Crab]

Thanks to both of you for the input.
HarryB--I used a 8" to 6" tapered reducer with the 8" side completely thru the thimble(about a foot long), the 8" is tight but that is a good thing. The other issue is that the chimney extends 4' or so below the thimble to a non-airtight cleanout. I have often wondered how much stove draft is lost thru this door, I will have to seal this also with the RTV.
PJ--I wonder PJ how you connected the 4" to the 6" that runs up from the stove? Again thanks, Crab

 

[pjmac]

I connected the 6" to the 4" with a 6" to 4" tapered reducer. This is inside the chimney and is not seen. The pipe that is showing is all 6" pipe. All of the 4" pipe is inside of the chimney.