Chimney Liner Question

[kleary]

Greetings,

I'm having a 100+ year-old chimney relined with 7" stainless flex. It will be venting a rebuilt 1985 Defiant rear-draft which will be routed directly into the chimney (no vertical stovepipe in the room). The stove is on the first floor, and the vertical run is approximately 30'. My question is this:

The sweep is not planning on capping the bottom leg of the takeoff Tee inside the chimney. He argues that this will allow soot and creasote to drop out (that's true), and will actually improve draft (I disagree, it adds huge "vacuum leaks" everywhere). I would prefer that he extend the bottom of the tee with more flex pipe down to a cleanout in the basement. This will allow me to do some testing to cap it or not.

Clearly the lower end of the Tee is capped in exterior applications. Does anyone have any experience with capping the Tee or not in relining applications? I need to decide quickly because once its installed (hopefully tomorrow), then I won't be able to get to it. And changing the project scope on this sweep is not to be taken lightly . . . he's drving me crazy! Thanks in Advance,

Kevin
Hamilton, MA

 

[DeanBrown3D]

I have a liner down to the basement. At the bottom is a Tee, capped up right at the bottom, and the middle part faces forward to the furnace. I don't see this being a major source of leaks. Its a fully internal chimney right up through the house.

 

[zzr7ky]

Hi -

I did mine the way you suggest this year. It drafts very well. I'd suggest another sweep; this one lacks something... An uncapped Tee is a wild departure from safe practice; picture flaming liquid creosote draining from the bottom.

All the best. You can also call any of the liner suppiers toll free asistance lines to answer these types of questions. These types of issues can/do void warranty and can cause insurance issues.

ATB,
Mike P

 

[Willhound]

Yikes! Not cap the bottom of the Tee? Where did this guy come from? Never heard of anyone even suggesting this as a joke.

 

[Shane]

Yea definately cap it. Talk about excessive flue gas cooling.

 

[kleary]

Thanks to all. The liner was installed yesterday and I lit my first fire last night to begin breaking things in (y'know, like burn the UPC code stickers off of the stove pipe sections!). The sweep capped the takeoff Tee at my insistence. In retrospect, here’re the tradeoffs that played into the cap or no-cap decision:

The Good: As expected the draft is excellent, and I can leave the large front doors wide-open almost right away.

The Bad: Placing the cap directly on the bottom of the takeoff Tee gives me only about 6” of volume to capture soot and debris from the 30’ vertical pipe. So I’ll have to keep an eye on that, and clean it out often.

The Alternative: Leaving the takeoff Tee uncapped is probably OK if your chimney is airtight and you can maintain the whole thing at a negative pressure. This will limit makeup air into the Tee from the bottom, which will allow the flue to behave as if the Tee is capped and give you a HUGE volume for capturing soot and debris (the whole bottom 10’ of masonry chimney). But my chimney is 140 years old with an unknown number of old, unused, wallpapered-over penetrations. So airtightness is a pipedream.

So I like the configuration I have . . . for now. But it has me thinking of my dream setup for next year. I figure I’ll extend the 7” pipe down to the basement and add a cleanout at the bottom. Further up I’ll add a Tee and a butterfly valve to allow controlled inlet of makeup air. Not that I’d ever use it, but it’d be fun to play with!

Anyway, thanks again. We’ll be in touch.

Kevin.