Moving a stove and installing a flue liner

[nkurz]

I moved last year to a house in southern Vermont. The house came with a woodstove with a suboptimal installation. The stove itself (a old Vermont Castings Resolute III) is in good shape, but the exhaust goes through a wall as Class A pipe, makes a right angle bend, and then enters the outside of a massive stone chimney. It then connects (badly) to a 8" round ceramic flue that goes to the top. We limped through with it like this last winter, but it's got some severe issues. Instead, I'd like to move the stove be in front of the fireplace next to it, and upgrade to an insulated stainless flue liner that goes all the way to the top of the chimney.



There's some trickiness with doing this, however, and I'm not sure of the best solution. The first issue is that the chimney is very tall (about 30 feet), and has a extremely heavy concrete cap on top of it. Removing the cap and getting safe access to insert a liner from the top is going to be very difficult, so I'm hoping that I can install the liner from the bottom, while keeping the top cap in place. I haven't seen this approach discussed anywhere, but is there any reason this can't be done?

Inside the fireplace, the moveable part the damper has rusted out and been removed (standing to right of fireplace in photo). Currently I've got about a 7.5" gap at a 45° angle between the fixed portion of the damper and the brick through which I can insert the flue, or I can use an angle grinder to enlarge the opening as necessary. The flue itself is a 12-13" round ceramic starting about 5' up, so once I get to there I should be fine. I'm assuming I'll drop a rope down the flue, put some sort of a pulley on the top, attach a pulling cone to the liner, and then guide it in from the inside while someone on the outside hauls on the rope. Is this going to work?

Once I can get it to the top, I'm assuming I can lock it off to a top plate that I slide underneath the heavy cap. I have about 10" to work with while I make the connection from a ladder. I'm thinking that an upside down top plate like this might work: https://www.rockfordchimneysupply.c...nts/round-liner-components/flat-top-plate.php. Is there any reason that a top plate like this cannot be installed upside down, with the collar pointing down, so the plate is flush with the top of the flue?

Backing up a little, is there a specific liner that should I use? Reading through the archives, the strong suggestion seems to be to avoid the lightweight two-ply smooth interior liners. It sounds like all the preinsulated liners are lightweight, but wrapping with insulation doesn't seem too difficult. And it seems useful that the heavier weight single wall liners are actually more flexible. I don't feel I understand the difference in alloys, though. I'm willing to pay more for a good liner that will last longer. Does anyone have a specific recommendation for a medium or heavy weight liner that I can buy as an end user?

The next part of the project will be blocking off the opening to the chimney, preferably in some insulated way. The usual approach seems to be to use just a blocking plate at the height of the old flue, but since we'd like to have a free-standing stove instead of an insert, and since the chimney is a gigantic uninsulated mass exposed directly to the outside, I'd rather not have the bricks and stonework exposed to the interior. My thought is to build some sort of insulated but non-combustible wall at the opening of the fireplace, with access the new flue via a thimble mounted in that new wall.

I'm not finding examples of people who have taken this approach, but I'm not sure why. Is it a bad idea for some reason? If it is reasonable, what would be the right materials to use to block off the opening? I could easily do a small piece of stud wall with an insulated thimble passing through, but it seems silly to build something new and combustible behind where the stove will go even if the stove pipe penetration itself is safe. Bricking it up would be non-combustible, but I'm not sure how to effectively insulate it. Perhaps two wythes of brick with perlite or mineral wool in between? Having thermal mass inside the insulation would be great if I can manage it.

If I get that far, the next step would probably be to enlarge the hearth. And we'll probably upgrade the stove as well to something modern. But these are separate questions that I can ask after I've figured out how to install the flue itself.

Thanks!

 

[bholler]

The first problem i see with your plan is the wood fireplace surround. I dont see how you will meet required clearances with it in place. As far as the liner install goes what we would do is drill a 2" hole through that concrete cap. Drop the cable of our hoist down through that and through the top plate. And no it cant be upside down that would funnel creosote down inside the chimney around the liner. Then just pull the liner up into place.

 

[nkurz]

The first problem i see with your plan is the wood fireplace surround.

It's true that I haven't figured out clearances yet. If we need to, we'll remove all the wood of the surround, or at least anything that is too close. But I think the clearances might be OK. Let's pretend we'll be using a Woodstock Progress Hybrid with a rear heat shield, since that's one of the stoves we're considering. This has a 7" rear clearance. If we put the stove 8-12" forward on the hearth, are we safe on the diagonals? And if we use a short piece of Class A pipe between the stove and and a thimble, doesn't this only require 2" clearance to combustible? But I don't feel like I understand the clearance requirements yet, and would love guidance, although I was thinking I'd save this question for later.

As far as the liner install goes what we would do is drill a 2" hole through that concrete cap. Drop the cable of our hoist down through that and through the top plate.

OK, so it sounds like you'd do approximately what I'm saying, but with bigger and stronger equipment. My impression is that getting a hoist to the location will be difficult, which is why I'm considering doing without it.

And no it cant be upside down that would funnel creosote down inside the chimney around the liner.

I'm not sure I'm following here. Is the seal directional? There should be no rain at this point, as I'm under the large cap. Is the alternative to find a cap with a shorter collar, that I can put upright underneath the cap with sufficient room for exhaust? I assume more space is better, but don't know how much I need.

 

[bholler]

It's true that I haven't figured out clearances yet. If we need to, we'll remove all the wood of the surround, or at least anything that is too close. But I think the clearances might be OK. Let's pretend we'll be using a Woodstock Progress Hybrid with a rear heat shield, since that's one of the stoves we're considering. This has a 7" rear clearance. If we put the stove 8-12" forward on the hearth, are we safe on the diagonals? And if we use a short piece of Class A pipe between the stove and and a thimble, doesn't this only require 2" clearance to combustible? But I don't feel like I understand the clearance requirements yet, and would love guidance, although I was thinking I'd save this question for later.



OK, so it sounds like you'd do approximately what I'm saying, but with bigger and stronger equipment. My impression is that getting a hoist to the location will be difficult, which is why I'm considering doing without it.



I'm not sure I'm following here. Is the seal directional? There should be no rain at this point, as I'm under the large cap. Is the alternative to find a cap with a shorter collar, that I can put upright underneath the cap with sufficient room for exhaust? I assume more space is better, but don't know how much I need.

You need to figure out how the stove will fit in the location first before anything else.

A peice of class a may work i dont know without being there to measure things.

Out hoist is just a hand crank boat winch on an aluminum frame. You could cheaply build one with wood or angle iron for a one time use. Pulling 30' of insulated liner without some sort of hoist will not be fun.

Most top plates raise up around the liner to direct water and debris away from the liner. If you install it upside down it will direct that debris (water wont really be an issue for you) towards the liner. What ever seal you put there is going to fail eventually due to heat and expansion and contraction. When it does you will be funneling creosote from the top down inside the chimney around your liner. That is bad.

 

[bholler]

As far as alloys go you really only need 304 for wood. But 316 is perfectly fine it just is more expensive.

To block things off just make a plate in the throat of the old fireplace. That will allow you access to the tee cap on the bottom of the liner for cleaning.

 

[nkurz]

You need to figure out how the stove will fit in the location first before anything else.

OK, thanks for your feedback so far. I'll try to figure out exact clearances for a particular stove, and then probably come back with more questions at that point.

 

[begreen]

The manual with clearances is on the Hearth.com wiki here in 3 parts:
https://www.hearth.com/talk/wiki/vermont-castings-older-stove-models/