Line Chimney (with what)? Adjust flue outlet height (how)? - UPDATED!

[Waulie]

My dad and I are both getting the Woodstock Progress, hopefully soon. I think I all set in my setup, but since we will be installing both stoves together, I'd thought I'd get some opinions on my dad's setup.

He will be rear venting into a 25-foot (from stove to top), interior, 7X11", clay lined masonry chimney. I suspect he will want to line this chimney, but one of the folks at Woodstock told him they would try it first as is. So, he is leaning towards holding off on the liner.

He will be rear venting straight into the chimney. Currently, he has an 8" pipe out of the chimney. While it would be easy to simply put a reducer there for the 6" exhaust, there is a slight problem. The center of the 8" pipe is about 27" above the hearth. The Progress has a 27.75" exhaust height. So the center of the pipe is about an inch low. What I'm thinking is if a 6" pipe was placed at the top of the existing 8" hole, we'd have a perfect height (i.e. no chimney cutting require). Ok, so here are some questions:

1. If he decided to just go ahead and line the chimney now, the snout could be situated at the top of the 8" hole and the exhaust height issue goes away. If a liner is recommended, what size? A 6" may not fit. I've read that tall, 5.5" liners can draft too well. Oval is significantly more expensive. Also, the stove is on the first floor but the chimney extends through the basement with a clean out door. Do you need to line all the way to the basement, or just terminate with a tee at the stove? Being an interior chimney in good shape, I don't think insulation is required. Maybe just pack some around the top to keep the portion above the roof a bit warmer?

2. If he decides to hold off on the liner, how do we adjust for the exhaust height? Could we simply mortar in a piece of 6" pipe (maybe stainless) at the top of the existing 8" pipe or hole? I assume there is a clay crock in the 8" hole, but the short piece of 8" pipe that comes out of the chimney is fixed somehow.

Thanks!

 

[begreen]

Is the PH flue outlet height 27.5" at the top or is it that height at the center? Before making a permanent installation I would be tempted to connect his PH with just a length of 6" black stove pipe with kaowool or roxul stuffed below and around it to seal it tight in the crock. Have the pipe end flush with the clay tile inside wall. Then run the stove for a while at various outdoor temps and see how it behaves.

PS: Do you have a picture of the PH's dimensions that you could post?

 

[Waulie]

PS: Do you have a picture of the PH’s dimensions that you could post?

I wish I did, but to my knowledge it doesn't exist yet. Based on their blog, it is 27.75 to the center of the rear exist. Since the 6" pipe would have to go right up against the top of the thimble to get the right height, should we put some furnace cement there to seal it up, with mineral wool around the sides and bottom?

I should probably add that the wood stove is my dad's only source of heat. So, if what we plan doesn't work it will be scramble for sure! I guess if it was temporary, we could alwas plug the Hearthstone back in. Nothing like moving TWO 700 pound stoves around multiple times. :grrr:

Thanks!

 

[begreen]

Sure, it wouldn't hurt to have a little furnace cement at top. You'll know better once you have the stove and can take accurate dimensions off of it.

 

[shawneyboy]

He will be rear venting into a 25-foot (from stove to top), interior, 7X11", clay lined masonry chimney. I suspect he will want to line this chimney, but one of the folks at Woodstock told him they would try it first as is. So, he is leaning towards holding off on the liner.

Wait someone at woodstock said to go from a 28 sq. inch area flue to a 77 sq. inch ??? That really surprises me.

 

[Waulie]

Wait someone at woodstock said to go from a 28 sq. inch area flue to a 77 sq. inch ??? That really surprises me.

Well, not quite. But, they did say "if it were me I would try it first" meaning before lining the chimney. The fireview manual explicity states that an 8X10" rectangular flue is the largest they recommend for the fireview. That's about the same size as 7X11".

Edit: The fireview manual also says an interior flue should be no more than 3 times the area of the stove exhaust. So, 28*3 = 84 in2. I guess they don't particularly discourage the practice.

 

[Waulie]

I'm resurrecting this question, because the install day is approaching and I had another couple questions.

Upon further inspection, there does not seem to be any crock in the masonry chimney. It looks like the chimney penetration consists of just an 8" single-wall pipe through the masonry. In order to get the proper height, we will need to remove the existing 8" pipe so the new 6" connection is situated at the top of the existing hole. Can we just replace it with a section of 6" pipe, or should we put some kind of crock in the hole? Clearances aren't an issue since the chimney is in the center of the great room with no adjacent combustibles.

We would like to keep it simple (but obviously safe) for now in case we need to line the chimney.

Thanks in advance!