NEWBIE HELP-Pellet Stove & Existing Chimney???

[larryz]

I just purchased a new Harman P68 freestanding pellet stove and I wanted to use an existing masonry chimney for venting. The stove will be in my basement which is unfinished with a concrete floor and concrete block walls. The existing masonry chimney has a standard 8" wall thimble going thru the block wall and into the chimney. The chimney has a clay liner, extends above the peak of the roof approximately 2 feet and is built within the home. There is approximately 4 feet of chimney on the outside of the house and it has a stainless steel chimney cap.

According to Harman's installation manual, installing into an existing masonry chimney provides excellent venting for normal operation and also provides for a natural draft in the event of a power failure.

Has anyone had experience with this type of installation? I have heard some say that you should install 4" pellet pipe inside your existing chimney and cap it about 1 foot above your masonry chimney. Other say that if your masonry chimney is in good condition, don't waste the money, just use it.

This is may first experience with a pellet stove and I want to do it right.

Thanks,
Larry

 

[elkimmeg]

There is the cross- sectional area issue an 8/8 flue has a cross-sectional area of about 49" A 4" vent about 13 sq inches
Code will allow up to 2/3 times the ceossectional area but in know way will it allow 4 times. There is also the length of travel that forced exhaust system can push. It will never push proper draft is a long to large 8/8 flue. Probably what needs to be done is reline the chimney witha 4" stainless steel liner Again read the manual and install it the recomended better way

 

[MountainStoveGuy]

Elk, pellet stoves are stubed up in flues all the time per the manufactures manual. Pellet stoves have a pressure exaust, and actually a large flue puts less backpressure on the unit, the problem is, that ash accumilates on the damper plate, and it harder to clean. There is no ill effects of stubbing in a pellet insert, and not doing a complete reline. BUT, most pros will do a complete reline, because there so much easier to service and clean. You cant go wrong lining it all the way up, so if the budget allows, do it. If you wont eat for a week becuase of the full liner, stub it up.

 

[larryz]

Thank you both for your replies.

I forgot to ask in the first question about the pipe itself. I understand that Simpson Duravent Pellet Pipe is supposed to be a good quality pipe. Is that a pipe that either of you would use in your own homes?

I was on there web site and I was a little confused about what type of adapters I would need to go from the 8" wall thimble to the 3" pellet pipe. They have the step down adapters, but I believe they are to be connected to another 8" pipe that goes into the thimble. I called there tech support but nobody has returned my call.

What is the best way to connect the 3" pellet pipe into the 8" masonry wall thimble?

Thanks again,
Larry

 

[MountainStoveGuy]

Quadrafire makes a top vent kit to hook up to existing 6" chimnies, it basicly brings the rear vent up top and has a 3-6" increaser there that looks nice and flush, so you dont have a bunch of step downs. You might talk to a harmon dealerto see if they have something similar.

 

[larryz]

Thanks.

Larry