Partially insulated Liner

[Mtnyota]

I have a odd tile liner in my heatform masonry chimney. The id of the tiles are 6" x 15". I am trying to install a vistaflame 1700 insert. My chimney is 12ft from the top of where the stove connection will be.

I have decided to go with the oval duravent system. The problem is that the chimney doesn't come straight up. The first 3ft from the top is vertical and then it angles and offsets about 6" down to the smoke shelf. Because of this I can't use the ridged pipe all the way down to the flex that goes through the damper. I will have to run 5ft flex from the insert up to a short length of insulated ridged. From the short insulated ridged will be a 3ft flex that runs up to the final 4ft ridged pipe.

My question is i don't imagine i could insulate the flex in the middle and get it down the chimney, so if my chimney tiles are in good shape, am I creating any problems?

 

[begreen]

How about using the Duraliner system instead. That way both the rigid and flex will be pre insulated.

 

[begreen]

No, that is Duraflex. Duraliner is a different product.

(broken link removed to http://www.duravent.com/Product.aspx?hProduct=6)

 

[Mtnyota]

Duraliner is what I ordered:

M&G Dura-Vent 6'' DuraLiner Oval-To-Oval Flex Pipe 36'' - 4636-OF

Use through damper and smoke shelf area. Built from 304 stainless steel. Use with DuraLiner Two-Ply Insulation Sleeve for zero clearance applications where flex extends into clay liner.

 

[Mtnyota]

Anyone have any advise?

 

[HaTaX]

Here's what I'd be worried about, that section of flex between the rigid sections has a rigid after it correct? What if that initial rigid section doesn't want to fit through the offset? And if it does fit through the offset, I'd go with rigid all the way even though you will be slanting 6" over a portion of the rise. I am looking at ordering that exact same system and got a fantastic deal from dynamitebuys after contacting them for a price match, (Found 2 sites with the lowest price) and they even threw in shipping! It isn't meant to be a cheap plug, but I was very happy with the prices I got back from them, about $200 less then I had planned on spending for the entire system.

Anyway, if you're getting the 6" oval system you should be able to get the insulation wrap on there without too much trouble, the flex is 4 3/4" and with the wrap it should be almost 6". And that's where I'd still strongly consider trying a rigid setup first, you gain back about 1 1/4" of space and you're still insulated. Perhaps a few shorter sections of rigid might give you enough flex at the joints to make the run?

Have any pictures down or up the chimney that might show the offset?

 

[Mtnyota]

It's kinda hard to get a decent pic, but you can kinda see the lower edge at the smoke shelf.

 

[HaTaX]

Hmmm, that doesn't look like too terrible of a bend there, I would think a shorter section of rigid would be able to pass that. The downside is that having 4' of pipe in 1' sections is more expensive, and you need to remember that each joint reduces the overall length 1 3/4" (95% sure that's the measurement, it was in the install PDF I believe).

How far is it from that bend to the damper plate? I'm guessing about 9 feet, and that would leave you with 4 x 2' sections that would probably pass that. I think a way to test it might be to take a cardboard box, cut it into similar dimensions as a 4' pipe, and then cut it down in length till you have something that passes easily. Tie a rope to the cardboard to retrieve it and push it down with whatever is handy.

You'll need help with the last section dropping it I think, you'll have to make the transition to the insulated flex and I think you'll have to pull the brace and plate off the top, affix the flex liner and lower it down slowly. Not much of the flex liner needs to make that bend, just enough to set the rigid straight, so a 3' section of flex and a 1' section of rigid to finish the top off. Since you only need to get the collar of the flex through the bend, the insulation shouldn't be much of an issue as it starts after the collar.

Just trying to offer some ideas, hard to know what you're up against without seeing it. Maybe something there will spark an idea.

 

[Jon1270]

I put in a round Duraliner a few months ago, and I don't think that HaTaX's idea of using short sections to achieve a bend is likely to work. The sections are very rigid and fit together tightly; there isn't the sort of play in the joints that would allow a useful bend.

 

[HaTaX]

Shoot, in that case you might have to look into fishing this from the bottom up if possible. If you can't bend the rigid enough to make it around the bend there, then there's no way to push down the rigid sections into the sloped portion.

Thanks for chiming in Jon, I haven't gotten my dirty mitts on it yet, few weeks for delivery and I won't be talking out my butt on it anymore.

So, if you can't bring the liner from the bottom up, then you might need to look into getting enough flex for the majority of the run and only have rigid on the top end. Even so you'll have to push the flex past the damper far enough to attach the rigid to the top end of the flex, no way to get a rigid section through that area is going to make things interesting.

 

[Mtnyota]

Thanks guys for the input. I'm pretty confident that the 3' solid will pass the upper bend. This still leaves me with 8ft of uninsulated flex, and unfortunately I think the upper flex will be in the attic area of the chimney. I can see some mortar ooze at the seems so I am doubtful that any insulation wrap will fit.

I know having the liner uninsulated is not the preferred method, but being that it is a interior chimney and I'm in a climate that only gets down to 30*F for a short period of time, will it create any problems.

 

[Jon1270]

This still leaves me with 8ft of uninsulated flex, and unfortunately I think the upper flex will be in the attic area of the chimney.

That doesn't sound so good. The flexible sections of Duraliner are single-wall and only rated for zero clearance if you add the insulation sleeve. I don't know what the narrower dimension is on the oval flex Duraliner, but I doubt it's small enough that you can get away without insulating that upper section of flex.

 

[Mtnyota]

I'm going to have my chimney inspected this weekend. As long as the tiles are in good shape there is not requirement for the zero-clearance rating, correct?

The narrow dimension of the oval is 4.75" wide. With the standard 1/2" insulation that would put me with in a 1/4" which won't fit.

 

[Jon1270]

I think you're right about that, but it's a big "if." I'm reaching the end of my minimal expertise on this topic, though.

 

[Jon1270]

There are also cast-in-place liners, that I think can be affordable. Supaflue is the name that comes to mind.

 

[HaTaX]

Shouldn't need the liner to be insulated if the flue tiles are intact and in good shape with no cracks, from what I can see they look good but you can only see the top section in that picture so I've got no idea what is below it. That's where a pro with an inspection camera will be very useful, they can make sure they're all in good repair before giving the go ahead with no insulation. If they're in good shape then the only advantage to having it insulated would be a better draft and some extra protection in case of a chimney fire.

Heh, I fished a cell phone with the video recording going down my flue on a trouble light. It is NOT a replacement for the CC camera the pro's use, but it gave me a good idea of the state of my flue tiles before calling them.