sealing off and insulating flue with liner

[bike66]

Hi:

I was wonder if anyone can help me. I removed my flue and placed a liner down the chimeny and directly into a Vermont Castings Intrepid stove. The stove is a free standing stove but I "inserted it" so the speak into my fireplace. I know that this isn't the best for heat, but I have 2 small children and like having the stove inside the fireplace so to speak.

The guys that installed the liner did a crapping job of sealing off the old flue with the liner inserted. They cut some sheet metal and fit two pieces around the liner and sealed it off that way. Not a good way of preventing heat from going up the chimney. In fact, one side has falling out. I was thinking of buying some insert insulation and sticking as musch as i can around the liner and then making a better seal similiar to what was in there with the two pieces of sheet metal. Can that insulation be used that way? Any other suggestions? See attched pics

Thanks

 

[semipro]

Intrepid,
I think the answers to your questions have already been posted in the "Hearth Room" and that's probably a more appropriate place for this question. Do a search for "blockoff plate" or "block off plate" or "block-off plate".

Many use only metal plates that are sealed to the masonry with high temp silicone. Others stuff rock wool in the gap to seal it off. I used a metal plate with a rock wool insulation layer on top. See this post for pictures: https://www.hearth.com/econtent/index.php/forums/viewthread/42686/

Good luck.

 

[Gooserider]

Moving to Hearth room, as it is more appropriate there, and as said, this has been covered very well, many times over... Also take a look in the Hearth Wiki, I seem to recall some articles there as well...

Note that you need to use high temp rated, fire proof insulation - i.e. Rock wool or equivalent, NOT standard building fiberglass. Also you need a solid, air tight barrier like sheet metal, in addition to whatever insulation you have - air will go right through just rockwool or other fiber insulation...

A couple of other items to think about -

1. That liner looks awfully crushed where it goes through your damper frame - not real good...

2. If the fireplace is on an outside wall, you are sending a lot of your heat out to warm up natures critters... You will get more heat into your house if you line the inside of the firebox with rockwool or other appropriate non-combustible insulation panels...

Gooserider

 

[bike66]

Thanks for your comments...I really appreciate it...The liner is a bit crushed when it goes through the flue frame...The pictures look worst than it really is because of the angle of the camera. How would I go about fixing that? I image I would need to grind away at the frame in the areas where it hits...Not sure if it's such a big deal considering the liner was installed fairly easily..

The insulation and a better made sheet metal seal sounds like what I'm planning. What's the least expensive insulation you would recommend?

 

[Gooserider]

Thanks for your comments...I really appreciate it...The liner is a bit crushed when it goes through the flue frame...The pictures look worst than it really is because of the angle of the camera. How would I go about fixing that? I image I would need to grind away at the frame in the areas where it hits...Not sure if it's such a big deal considering the liner was installed fairly easily..

The insulation and a better made sheet metal seal sounds like what I'm planning. What's the least expensive insulation you would recommend?

Again, searching will find lots of threads on how to remove or modify the damper frame to get room for the liner... However if the liner in the worst area still has about the same cross section as a 6" round liner (about 28 sq in) then it shouldn't be a big problem, which is a good thing as it is non-trivial to fix once the liner is in place.... Given the existing setup, as long as you aren't getting draft problems, then I'd try to live with it as is. The Intrepid is one of the smaller VC stoves, so it may be OK.

I would say top priority is getting a good fitting seal around a metal blockoff plate is your first priority, putting some rock wool batting above the plate is good but optional... To insulate the fireplace box itself, I know they make panels or blankets from rockwool or similar, but I'm not sure on sources and prices as it isn't something I've had to do myself - however the basic idea is to use the panels or blankets and fasten them to the inside of the fireplace with tapcons and large washers - and then hit the installed insulation with a good layer of hi-temp black spraypaint so that it looks a bit better... Key thing is to make sure everything you use is non-combustible.

Gooserider

 

[BrotherBart]

I have a free standing stove inside a fireplace also. I have found that it is best to install a sheet metal block off plate even with the lintel in the front of the fire place sloped slightly down to the rear wall. This lets heat coming off the stove roll right out into the room. And contrary to folklore on this site all of your heat doesn't go screaming out the back of the fireplace.

It can be anchored to the lintel and the back wall of the fireplace with Tapcons that are available at any hardware store. Instructions on making one used to be in the Hearth Wiki but have disappeared.