Question about draft of woodstock stoves

[Havendalefarm]

In another post it was pointed out that a stove was smoking due to cap left off tee on liner. That made me wonder if the same thing would happen if stove is hooked to interior masonry chimney with cleanout down in the basement.Do these stoves just have to have an insulated flue? Kinda defeats some of the benefits of having the masonry chimney running up through the middle of the house. I don't know about others but we have grown to like the warmth radiating out in an upstairs hallway.Chimney is insulated around the outside where it goes into the cold roof area though, this had been a problem in years past and always lead to a warm roof and ice. Our bottom cleanout is about eight feet below where the stove ties in. Our stove has always drafted well, maybe even a little too well when it gets real cold outside. This has always acted as a kind of automatic thermostat on the stove.

 

[ddddddden]

A chimney liner pipe of the same diameter as the stove's flue collar is the optimal setup. This is true for any brand of stove. Unless you have clearance/code issues, you probably don't need insulation in an interior chimney, so you could do this for ~ $300 for the liner kit. I would just go ahead and do it.

That said, you can use the masonry flue, as long as it's not too big. . .s'posed to be no more than 2x the cross-section of the stove's flue. 6" diameter ~ 28 sq in, so less than 56 sq in. . .8 x 8 is about as big as you would want to go with a masonry flue. Then you have to get a good connection between the stove pipe and the masonry, which will probably be a PITA at cleaning time. And you would have to worry about air leaks from that clean-out in the basement. . .just do the 6" liner.

 

[Havendalefarm]

We have talke about putting rigid liner in it since it is just one straight run. I guess I just wondered if I really had to line the bottom eight feet and if so , wouldnt that have air in it as well.

 

[ddddddden]

"Liner" basically = stove pipe. You may connect to different pipe inside the room, for example, but the idea is to have 1 run of pipe from the stove collar to daylight. I've read some good reasons why rigid is superior, but I went with flex pipe, and have no regrets.

Also, most masonry chimneys are probably a straight run. . .until you hit the smoke shelf and the damper area, and then the typical install of rigid pipe connects to a short length of flex pipe to snake through this area. I didn't want any potential air leaks at pipe joints to compromise my draft, so I went with a single 25' piece of flex pipe for the whole run.

 

[Waulie]

I use my 7X7" clay-lined masonry chimney with my Progress. It is a tall, interior chimney that also has a clean out door in the basement, one floor below the stove. No issues here with smoke smell.

My dad uses his 7X11 clay-lined masonry chimney with his Progress. Also a tall, interior chimney with a clean out one level below the stove. No issues there.

IIRC, the manual even says the maximum cross section for the chimney flue is 80 square inches.

I would try it first and see. If you have issues, then you can line it. I'm sure that's would Woodstock would recommend as well (they did with us).

 

[charly]

I think my Tee without the cap was an issue because my masonry chimney was an exterior set up and cold air was getting drawn into my tee past my clean out door..thus creating a poor draft once things where slowed down...My clean out door is only about a foot below my tee bottom. Warm air from a basement might not be such an issue, plus your chimney is inside...I'm just glad that it was such a simple fix as to just adding a tee cap..that slight smoke smell was annoying..

 

[ddddddden]

Chimney/flue performance seems to be a very YMMV thing. Here's another PH owner who installed with a liner. . .was not happy until he insulated the liner.

https://www.hearth.com/talk/threads...ted-the-flue-and-wow-what-a-difference.93543/

I do not disagree about trying the masonry first, but unless you already have a stove with a 6" flue connected to it and are just swapping in the PH, you will be buying some parts for the install. Thimble, misc. pipe, etc. could quickly add up to a few hundred. Here's a full liner kit for $345 shipped. . .less if you don't need 25'.

(broken link removed to http://www.ebay.com/itm/Chimney-Liner-6-x25-Kit-MagnaFlex-not-duravent-/170644939230?pt=US_Fireplaces&hash=item27bb3b21de)

. . .I just wondered if I really had to line the bottom eight feet and if so , wouldnt that have air in it as well.

I re-read this, and I'm not sure what you mean here. If you're talking about the last 8' to the clean-out in the basement, a liner connected to the stove would make that irrelevant.

This article has some good diagrams of liner configs. . .and apparently the 2x CSA rule is for exterior chimneys. 3x CSA for interior chimneys, so there's your 80 sq in.

(broken link removed to http://www.chimneysweeponline.com/stainlessliner.htm)

 

[Waulie]

I agree. I think by far the biggest difference is interior vs. exterior chimneys. Also, I think having extra height is importent when you increase flue size.

The OP should only need (at most) a 6" to 8" inceaser if his previous stove had an 8" outlet to give that clay flue a try.

Obviously, lining won't hurt! If you do and your existing flue is sound, there should be no need to insulate. But, I would probably stuff some Roxul between the liner and old flue in the top part above the roof line.

 

[Havendalefarm]

So what I am seeing is that if you line the chimney you must cap the tee. I guess this would mean pulling the pipe apart at the thimble and cleaning out any creasote that gets brushed down from there?Don't see how you would get the cap off the tee to let it go down to the cleanout as it does now.

 

[ddddddden]

AFAIK, which is not that far, if you didn't have access to the back, you wouldn't even want to use a tee for a through-wall install; just an elbow.

Yeah, disconnect stove pipe at the thimble for cleaning. . .again, AFAIK. My setup is different.

I wouldn't leave the cap off of the tee in any install. Draft is created by vacuum in the chimney. Air that can be pulled in at the tee or leaky pipe joints = air that won't be drawn through the stove = weaker draft. Also, air drawn from any source other than the stove will not be hot air. It will cool the flue, again reducing draft. If you have a 30' interior chimney, your draft may be strong enough anyhow, but this site is littered with posts by folks who have draft problems due to the chimney. Modern stoves with restrictive plumbing for secondary burn are more sensitive to the chimney setup.

 

[Backwoods Savage]

In another post it was pointed out that a stove was smoking due to cap left off tee on liner. That made me wonder if the same thing would happen if stove is hooked to interior masonry chimney with cleanout down in the basement.Do these stoves just have to have an insulated flue? Kinda defeats some of the benefits of having the masonry chimney running up through the middle of the house. I don't know about others but we have grown to like the warmth radiating out in an upstairs hallway.Chimney is insulated around the outside where it goes into the cold roof area though, this had been a problem in years past and always lead to a warm roof and ice. Our bottom cleanout is about eight feet below where the stove ties in. Our stove has always drafted well, maybe even a little too well when it gets real cold outside. This has always acted as a kind of automatic thermostat on the stove.

If you've used this setup and all has been well then why would you think anything would change? If you like it and it works, there should be no need of fixing it. However, a liner will help with any stove. Is it needed? Just depends on your situation. Many have not needed one but many have needed one. On our setup, we go through the wall then up alongside the house. No problem and it is not in a chase either.