Do I need to insulate my flue? I have an interior fireplace that I would like to update with a new stove. I have a terra cota flue that measures 6.625 x 10.75 on the inside, with minor alignment offsets of about a quarter inch in some places. Is it critical that I insulate, or does a sealed cap on the top of the chimney and a damper plate do an adequate job of it? Thoughts? How much do you REALLY need to leave for insulation if that becomes the case? Rockford says .75" on each side, which definitely rules out a six inch round flue. Thanks.
Insulating a chimney is always best, but not always necessary. Sealing and insulating the top cap and block off plate goes a long ways, especially on an interior chimney. An ovalized liner will give you more room for insulation.
I understand it's recommended, and I can totally see why, but at my last place I had a relatively short chimney and a 6" round liner with no insulation. Stove was a hearthstone Clydesdale insert, block off plate in the fireplace and a sealed cap. My chimney was a masonry chimney, terra cotta lined and between my living room and garage. The garage stayed pretty warm and I never had any trouble. I think performance is increased with insulation but I don't think it's absolutely necessary in all cases.
It's not absolutely necessary but if you are going to go to the effort of lining the chimney I would highly recommend it. I see Rockford now has preinsulated flex liners which they did not have when I did mine a few years ago. A 5" preinsulated might fit or the other option is to put in the 6" uninsulated and do a pour down insulation. It does make a difference but with an interior chimney it isn't quite as needed. If you choose not to insulate I would at least use roxul around your block off plate and stuff some around the top below your top cap.
A 5" insulated would definitely fit, but are you talking round? That won't do, since stove exit is 6". If you're talking oval, then it may work. In your experience, how much extra is added to a liner when it's fitted with the insulation and wire mesh? Rockford said it's half an inch thick, and if it's overlapped that would make it inch and a half. They do offer quarter inch insulation I think. All this is because I don't want a nightmare trying to fit a golf ball through a garden hose. Thanks.
I'm going to test this pretty good, but I think a 4.5 x 9.1 flue with added insulation will fit down all right.
You wouldn't have to overlap the insulation blanket, you can wrap it and butt the ends up then it has stainless tape that goes over the seam. I guess I don't understand what you mean when you say a 5" round would not work because the stove exit is 6". When you get toward the bottom of the liner down where it meets the stove you don't need to wrap insulation right to the end as it will stay plenty warm right at the stove. You would need a 5" to 6' adapter is all. I would not want to go down too much smaller than 5" like the 4.5" as it may reduce your draw as will the 5" a little bit. Some pictures of your set up would help us too. We are here to help.
Edit to the above post: I see you are talking about a 4.5" x 9.1" oval. That may do fine given the fact that it is wide to make up for the narrow side. Pictures would still be helpful.
I always preach how glad I am that I insulated. But you say yours is interior. Might be OK plain. Would be interested to hear from other interior installs. There have been some who claim you're better without it, (for interior).
I would agree might be okay, but I don't see how you could be better without it. The warmer the flue stays, the better. Not at all trying to start an argument or a back and forth. Just my 2 cents.
yeah....that's why I would like to hear from others with experience in the same situation. Mostly curious. My dad, for example...once built a wine rack on a kitchen wall. After a winter or 2, they realized that some of the wine bottles were getting screwed up by excessive heat. The (un-insulated) chimney and stove/insert was on the adjoining wall. So, there we have it. Heat that would've gone up the chimney was being scavenged to the kitchen; at least in part. In theory, at least.
One other advantage of insulating, according to Rockford, is that system would be unharmed by a typical chimney fire. They give temperature specs, etc. in their literature. I don't intend to ever test this out though.
Well the problem is solved, I think. I was able to make a pretty nifty tool, a piece of plywood the size of a 4.5 x 9.1 flue with insulation wrapped around it, so 6 x 10.6. I made it on the larger side just to be safe. This piece I screwed to the end of a long pole and stuck it down my chimney. My wife was quite entertained. Well, it went the whole way down the flue! Now I don't have to settle for not insulating, it will fit. Now the only thing left to do is bust a couple bricks out and cut out the damper( as that is not large enough. Any thoughts or referrals to other threads would be great. If I have some time I'll put up some pictures of the existing set-up
That's why I have 8' of single wall connector pipe. Cheaper, more heat in the house. It drafts fine and stays clean. No doubt double wall would draft better and stay cleaner. I'll put up with an extra chimney sweeping per year. My 2 cents.
The only time you need to insulate the liner is when the masonry chimney is not code compliant or unsafe. The insulation contains the heat if the masonry is unable. Otherwise it is not required. That said, an insulated flue will always draft better than a naked one.
