We are converting our fireplace and installing a VC Montpelier this fall. I have done a lot of reading on this wonderful forum and it seems like insulating around the stove pipe and installing block off plates are 2 frequent recommendations. The interior dimensions of my clay tile flue are 7x11". I was told that the 6" stove pipe has an outer dimension close to 6.5". My installer was worried that if he wrapped the pipe with insulation then it would get caught up and ripped and be difficult to install. He said that he doesn't like ovalizing pipes because of the restricted air flow. It is an exterior chimney. He said that he usually packs insulation up around the first 3 or 4 feet of pipe and the top 3 or 4 feet of the pipe. He said that this seals up the air space really well. He also said that they do use the insulation wrap in bigger flues, but mine was too small. He also only installs block off plates if he is pouring vermiculite insulation around the pipe, which he can come back and do if I have any draft problems. Any thoughts and recommendations would be greatly appreciated.
Insulating in a 7x11" Flue
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Welcome. 7x11 sounds small for a fireplace flue. However, if that is what it is then the dilemma you face is common. 6" insulated liner is 8" OD. It would not fit down that pipe. Some options are:
• break out the tiles to make room for a proper insulated stainless liner system.
• install an uninsulated liner but have less protection and likely more build up due to cooling flue gases. If the chimney is on the short side (under 15') then poor draft may result.
• install a preinsulated liner like DuraLiner that is 6 5/8" in diameter. This will only work if it's a straight shot down.
Regardless of choice, have an insulated block-off plate installed to keep more of the heat from the insert in the house and less heading outdoor through the mass of masonry.
• break out the tiles to make room for a proper insulated stainless liner system.
• install an uninsulated liner but have less protection and likely more build up due to cooling flue gases. If the chimney is on the short side (under 15') then poor draft may result.
• install a preinsulated liner like DuraLiner that is 6 5/8" in diameter. This will only work if it's a straight shot down.
Regardless of choice, have an insulated block-off plate installed to keep more of the heat from the insert in the house and less heading outdoor through the mass of masonry.
In having no block-off on a partly-insulated liner, you may get away without any serious draft problems but I expect you could still have pretty serious heat loss on an external chimney. As the exterior masonry is exposed to the cold, it is going to want to pull heat from the flue and interior masonry, and the more you let it take the more it WILL take. Even with some insulation packed around, without a more solid blocking mechanism there could still be warm air flowing up the flue.
Was your installer suggesting loose vermiculite/perlite, or an approved mix? I used loose, but as far as I know that is technically not to code, as it is not an approved application for my liner. To me (and some others) that is a "technicality" I don't worry about, but you should be aware it is possibly not code-compliant.
If you are comfortable using perlite and plan on a blockoff plate anyway, loose perlite is extremely inexpensive and easy to pour so you might just want to do it on the initial install. But you want to be sure it cannot sift through the blockoff. I put a "plug" layer of a few inches of perlite/mortar at the base of my liner to ensure the loose perlite above would not sneak down.
If the installer was talking about TherMix or GoldenFlue or another approved perlite/mix product, did he give you a quote on how much that would be? The down side of those application is they sort of "lock" the liner in, making any return to a fireplace flue a real PITA. But it seems to me it would make sense in your install if you don't anticipate removing the liner.
The installer was going to do an approved mix for $500 more. I'll ask about the loose, but I don't think it's code here and since I'm not doing the install then it's probably not an option.
Thanks for the quick and informative responses. This is a great forum! I just found another dealer who is 50 minutes away, $1350 cheaper and willing to travel. His house is actually pretty close to mine and he stopped by today. He said that he can do a double wall insulated liner for $400 more and a block off plate for $100 more. I assume its like the DuraLiner which should squeeze in. He seemed to be more willing to work with me. Even with the double liner and block off plate, he would still be $850 cheaper than the other store. The more expensive store has a lot of overhead, frequent TV ads, etc. I'll probably go with him.
Thanks for the quick and informative responses. This is a great forum! I just found another dealer who is 50 minutes away, $1350 cheaper and willing to travel. His house is actually pretty close to mine and he stopped by today. He said that he can do a double wall insulated liner for $400 more and a block off plate for $100 more. I assume its like the DuraLiner which should squeeze in. He seemed to be more willing to work with me. Even with the double liner and block off plate, he would still be $850 cheaper than the other store. The more expensive store has a lot of overhead, frequent TV ads, etc. I'll probably go with him.
you dont want to use loose fill it is no longer approved because it settles over time leaving a rock hard lump at the bottom and a few feet uninsulated at the top. Ovalizing is still an option you would need to bump up to 7" pipe to maintain the proper volume but if you do that it will work just fine.
OK, so the new installer that I found seems great. He is ordering a pre-insulated liner. It is the Champion brand by Olympia. He is charging $400 more for the insulated liner and $100 for a block off plate. He said that I had about 1/4" to spare and that if they can't fit it through the chimney that I would still have to pay for it since it is special order and will be a little dinged up. I figure i can sell it on ebay or craigslist and then if I decide to insulate later I can do the poured mixture from above, however I feel like they should be able to fit it. The guy that rebuilt our chimney in 1995 did a real good job. I'm hoping it's a smooth and straight path. He said the install should be in a couple of weeks. I just finished stacking my 2 cords and splitting about 1/2 cord into smaller pieces. I measured 15-20% moisture content. Can't wait to get burning. It's 80F here now, but it won't be long.
Quick question. Do most installers sweep the chimney before they install? Should I do it? Give the 7"x11" brush one last party?
Quick question. Do most installers sweep the chimney before they install? Should I do it? Give the 7"x11" brush one last party?
The chimney definitely needs to be swept first. Ask the installer if they plan on doing this before installing.
What size preinsulated are they putting in that is going to fit down a 7x11? I doubt very much that it will work. And yes it needs cmpletly cleaned paying special attention to the smoke chamber and if you have one the smoke shelf
Thanks so much for everyone's help! I need to speak with the installer on Monday. He said there would be 1/4" to spare, but they use Olympia brand hybrid insulated liner. I couldn't find the outer dimension on their website but some other sites mentioned they are 1" bigger on each side, so a 6" would be 8"! Not sure what he's planning. I know Duravent makes 6 5/8" O.D. liners. I guess that would have a chance of making it down.
1) What other manufactures make pre insulated liners that might fit?
2) Should I consider ovalizing?
3) Should I consider a 5.5" liner?
4) Maybe a pour down mixture is my best option? I was just hoping to keep the fireplace option available for the future reference just in case.
1) What other manufactures make pre insulated liners that might fit?
2) Should I consider ovalizing?
3) Should I consider a 5.5" liner?
4) Maybe a pour down mixture is my best option? I was just hoping to keep the fireplace option available for the future reference just in case.
it will be about 7.25"
Lots but it doesn't need to be preinsulated
Probably Or braking out the old liners
Maybe check with the stove manufacturer
You can do that but it will not bring it up to code because there is no way you will get the required thickness of insulation. And by the way you can still pull the liner and clean out the insulation.
kennyp2339
Minister of Fire
I think you will be fine, your installer is probably going to use a pulling cone to get the liner down the chimney. Insulated liners are nice but if you have the required masonry clearances they are not needed. Yes you will have to be mindful of keeping your flue clean, but its more or less the quality of your fuel and burning practices that will determine whether or not you need to sweep your chimney once, twice, four times a year.
Block off plates on in insert or free standing unit in an existing fireplace / chimney are a must in my book.
A few years ago my friend and I installed a Englander NC30 in his fireplace, (we replaced a very small insert that didn't make any heat) His house is only 900 sq ft, the NC30 made the house a little warmer in the winter, but he was burning full loads, loading every 6-8 hours, his little house was pushing 4.5 - 5 cords a year, we just surmised and said that his house needed to be insulated better.
Last winter we tore down his existing mantel, because of this form I had the confidence and knowledge to build a homemade block off plate using sheet metal, dura-rock, and roxal insulation, I packed the upper part of the existing fire place with roxal. and put the plate in.
The NC30 now is way to big for his place, he went from burning full loads of wood to just being able to burn a 3 or 4 pieces at once with the outside window open.
Block off plates on in insert or free standing unit in an existing fireplace / chimney are a must in my book.
A few years ago my friend and I installed a Englander NC30 in his fireplace, (we replaced a very small insert that didn't make any heat) His house is only 900 sq ft, the NC30 made the house a little warmer in the winter, but he was burning full loads, loading every 6-8 hours, his little house was pushing 4.5 - 5 cords a year, we just surmised and said that his house needed to be insulated better.
Last winter we tore down his existing mantel, because of this form I had the confidence and knowledge to build a homemade block off plate using sheet metal, dura-rock, and roxal insulation, I packed the upper part of the existing fire place with roxal. and put the plate in.
The NC30 now is way to big for his place, he went from burning full loads of wood to just being able to burn a 3 or 4 pieces at once with the outside window open.
Agreed but how many chimneys out there do you think have those clearances? In my experience it is very few.
kennyp2339
Minister of Fire
I think the code says for an outside chimney you only need 1" of clearance, considering what the code is plus the fact that 25 years ago this type of install would probably have been a slammer install, I think the OP will be fine with just the liner, but you are absolutely right, most chimneys unless new construction do not have the required clearances
It may be fine yes but the risk gets greater as time goes on due to pyrolosis the more that wood gets heated up the lower the kindling point gets. So after 25 years of being heated the kindling point can be pretty low. Also i have seen many new construction chimneys that passed inspection with flying colors that have nowhere near the required clearances.
Also if they are using olympia's products they require insulation on all liners servicing solid fuel burning appliances regardless of clearances. As do most liner manufacturers.
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OK, so I talked to the installer. He plans on using a 5.5" Olympia pre-insulated liner. He said that my chimney looks looks like a pretty smooth straight shot and he's pretty confident that it will fit. I called Olympia and they said that the outer diameter is 6 7/8", so it will be a pretty tight fit. I also got the vibe (which seems pretty common with most installers) that I really don't need the insulated liner, however this forum taught me otherwise. He said that you just use some newspaper that you hold up to get the draft started. I look forward to a cleaner and safer chimney with the insulated liner. I just hope that it fits. The 6" insulated definitely won't fit. I assume that 5.5" is ok? He was worried that if he wrapped a liner with insulation that it would get ripped up on the way down. I probably would have had to go with a 1/4" wrap anyway, so the pre-insulated with the outer metal layer seems like a better choice. FYI, the top of my chimney is 25' above the hearth. He is planning on sweeping the chimney first and said that he will make a block off plate with sheet metal and insulate it with Roxul.
At 25ft you will be fine with 5.5" insulated, you might have a slight overdraft on really cold days. Just don't forget the 6" to 5.5" stainless converter.
![[Hearth.com] Insulating in a 7x11" Flue](https://www.hearth.com/talk/data/attachments/165/165059-348d9cbc38f2fd52ad5317c55cf96031.jpg?hash=nhYuQledXF "[Hearth.com] Insulating in a 7x11\" Flue")
It's in! So the install went pretty well. They could not, however, get the insulated liner down. He barely fit a 5.5" uninsulated liner down. They did do a nice block off plate with roxul, and the packed roxul at the top and sealed it up really well. If I want to go insulated, then I'll have to have them back to do a poured mixture. That being said, the stove is performing amazingly! My wood is nicely seasoned. Fires start right up and and are running really hot. I'm getting great secondary burn and the glass is staying clean. So far I'm really happy. Draft seems great. The only time I get a little smoke coming in is if it's not hot and the door is open too much. Otherwise, life is good. Thanks to everyone for all of the good info!
Question. If the fire isn't that hot and we open the door with the flu vent all of the way open, we get some smoke in the room sometimes. Is this because my liner isn't insulated? If I have a poured insulation mix put in, are there any other downsides besides making it hard to return to a fireplace? What if the stainless steel liner needs to be replaced?
I'm a little worried that they "couldn't fit" the insulated liner because they they left base of my old lock top damper up at the top of the chimney. I don't know why they didn't take this off. I think it has a smaller diameter than the clay tile itself. That would suck if that were the case.
I'm a little worried that they "couldn't fit" the insulated liner because they they left base of my old lock top damper up at the top of the chimney. I don't know why they didn't take this off. I think it has a smaller diameter than the clay tile itself. That would suck if that were the case.
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This may improve with colder weather. In milder weather, open the air control, wait 10 seconds, then slowly open the door.
Thanks for the info. So do you think that doing a poured insulation between the clay tile and stainless flue would help much with the smoke? I guess I should reserve judgment until colder weather.
Just my two 7X11 chimney owning opinion, but no. It won't make a dimes worth of difference. Most of the liner is gonna be touching the flue tiles anyway. And where it isn't the hot air in the void will insulate just fine.
it will make a difference. Air is a good insulater if it is not allowed to move even sealed top and bottom the air will move allot inside that chimney and transfer allot of heat to the masonry. And no most of the liner will not be touching the clay only 2 points will be touching. I know yours works just fine but others may not.
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