Smooth Wall vs Corrugated Chimney Liner

[angryhippie]

I am looking at getting a new 6", 25' chimney liner. I've looked at both Chimney Liner Direct and Rockford (though I'm seeing Rockford cheaper on Amazon than on their website). What is the general consensus about smooth wall vs corrugated flex liner? Corrugated is obviously cheaper, but is smooth wall really better?

Also, I have limited clearance for the tee with cleanout, I see that a short tee is made, is there an advantage to going with the standard one over the short one. I can always chip away a little more room if I need to, but I'm not sure I'll be able to remove the bottom cap easily in either situation so I'd have to just stick the vacuum back there to clean it out.

 

[bholler]

What is the general consensus about smooth wall vs corrugated flex liner? Corrugated is obviously cheaper, but is smooth wall really better?

That depends what smooth wall you are talking about. If it is the double layer thin wall stuff i honestly would never put one of them in again. but mid weight and heavy wall liners are also smooth wall and are absolutely better liners that regular light wall.

 

[FyreFly]

This is the exact question I came here to research. The house we purchased a couple years ago has a (broken link removed to http://jotul.com/us/products/fireplace-inserts/jotul-c-550-rockland-cb) insert (installed in 2010). We don't think we're getting the most out of it.

It currently has a single wall corrugated liner (which I'm pretty sure is not insulated) and we were wondering if it would be worth it to have a better liner installed.

If we did upgrade the liner, what improvement should we be expecting?

That depends what smooth wall you are talking about. If it is the double layer thin wall stuff i honestly would never put one of them in again. but mid weight and heavy wall liners are also smooth wall and are absolutely better liners that regular light wall.

Do you have any specific recommendations?

 

[angryhippie]

That depends what smooth wall you are talking about. If it is the double layer thin wall stuff i honestly would never put one of them in again. but mid weight and heavy wall liners are also smooth wall and are absolutely better liners that regular light wall.

I was looking at the Rockwood Smooth wall flexible pipe. Says it's .013 total thickness. Why would you not choose to go with the lightweight smooth wall?

I burn maybe 2 cords a year total, if that makes a difference.

 

[Grisu]

If we did upgrade the liner, what improvement should we be expecting?

The liner could help with draft although just changing the type would probably not make much of a difference; the insulation could. How much creosote do you get when cleaning the liner?

In which way does the insert perform poorly? Do you have smoke spillage when opening the door? Problems closing the air control without smoldering the fire? Those could be signs of insufficient draft but could as well be explained by wet wood. For how long has the split wood been stacked in a spot with lots of sun and wind?

 

[angryhippie]

It currently has a single wall corrugated liner (which I'm pretty sure is not insulated) and we were wondering if it would be worth it to have a better liner installed.

Is your chimney on the interior of your house and is it terra cotta lined? From what I've gathered in my research (which I could be wrong), insulation isn't as critical. I wish I were in your shoes though, I'd save my money, pull the liner, and just insulate that over buying a whole new liner.

 

[angryhippie]

I see what everyone was saying about the lightweight smooth wall pipe. Looks like the general consensus is to go with either the standard Flex King Pipe or go with the Flex King HD pipe that's thicker. The flex king with insulation is about $600. The flex king HD is about $850. Is the extra $250 really worth it or can I save my money?

 

[bholler]

Is your chimney on the interior of your house and is it terra cotta lined? From what I've gathered in my research (which I could be wrong), insulation isn't as critical.

Whether or not a liner needs insulated depends on what clearance to combustibles you have. If it is an interior chimney you need 2" of clearance between the outside of the chimney and anything combustible. An exterior chimney needs 1". Very few chimneys have this and most of the time it is very difficult to verify that clearance for the entire chimney so it is a safe bet that you need insulation.

The flex king with insulation is about $600. The flex king HD is about $850. Is the extra $250 really worth it or can I save my money?

I think it is worth the money the heavy wall is much more durable but you need to make that decision yourself.

 

[jatoxico]

Just out of curiosity one thing that gets discussed is that a quality smooth wall liner creates less turbulence and therefore drafts better and stays cleaner. Any pros have an opinion on that?

 

[bholler]

Just out of curiosity one thing that gets discussed is that a quality smooth wall liner creates less turbulence and therefore drafts better and stays cleaner. Any pros have an opinion on that?

Yes that is an issue but the effect is not that much really. But like i have said before all that we will install for wood is either heavy or midweight which are both smooth so it is not an isssue with our installs. But we work on lots of light wall liners and i don't see a higher percentage of them being overly dirty

 

[EJL923]

This is the exact question I came here to research. The house we purchased a couple years ago has a (broken link removed to http://jotul.com/us/products/fireplace-inserts/jotul-c-550-rockland-cb) insert (installed in 2010). We don't think we're getting the most out of it.

It currently has a single wall corrugated liner (which I'm pretty sure is not insulated) and we were wondering if it would be worth it to have a better liner installed.

If we did upgrade the liner, what improvement should we be expecting?


Do you have any specific recommendations?

I have this stove and corrugated single wall. I have an internal chimney about 23', it drafts like no other. The stove itself i have never been completely happy with. Ive done a lot of adjustments over the years to make it good enough.

 

[FyreFly]

The liner could help with draft although just changing the type would probably not make much of a difference; the insulation could. How much creosote do you get when cleaning the liner?

I'm not really sure. Purchased a soot eater and will be cleaning it for the first time this year.

In which way does the insert perform poorly? Do you have smoke spillage when opening the door? Problems closing the air control without smoldering the fire?

It seems like if I don't have the air control setting full open we get build-up on the inside glass and poor performance. When it's wide open it'll blaze fine but I don't think that's the most efficient way to be using it (I'm a stove novice, having only had use of an open pit fireplace decades ago).

Those could be signs of insufficient draft but could as well be explained by wet wood. For how long has the split wood been stacked in a spot with lots of sun and wind?

We mostly used eco bricks last year, probably in a 5-1 (bricks/wood) ratio so I don't think it's wet wood.

 

[FyreFly]

I have this stove and corrugated single wall. I have an internal chimney about 23', it drafts like no other. The stove itself i have never been completely happy with. Ive done a lot of adjustments over the years to make it good enough.

I'd PM you about this, but I'm not seeing that option...

My biggest problems with the stove are that it seems a little small, the blower is loud, and I feel like I've got to leave the air-control wide open to get a clean burn.

What adjustments have you made? Have you ever cleaned your liner yourself? If so, any tips on how you proceeded with this stove?

 

[FyreFly]

Is your chimney on the interior of your house and is it terra cotta lined? From what I've gathered in my research (which I could be wrong), insulation isn't as critical. I wish I were in your shoes though, I'd save my money, pull the liner, and just insulate that over buying a whole new liner.

The chimney is on the interior of the house (an extension of the house was built around it) and it is terracotta lined.

Aside from getting a better/cleaner burn I was hoping that a smooth wall and well-insulated liner would make cleaning easier. I guess I'm just dreading my first clean and every time I look at the corrugation it seems like a terrible idea for a liner.

 

[Grisu]

My biggest problems with the stove are that it seems a little small, the blower is loud, and I feel like I've got to leave the air-control wide open to get a clean burn.

Unfortunately, the C550 is more a mid-size insert than a large one although Jotul advertises it differently. And as a flush insert it relies more on the blower although if you have a proper block-off plate and time you could also turn it off and wait for the masonry to heat up. That heat will then slowly be released into your home.

Now, leaving the air control wide open to get a clean burn sounds like a wood issue. For how long has the split firewood been stacked in a sunny and windy spot? Did you ever measure its internal moisture content by splitting a few pieces in half and pressing the pins of a moisture meter in the center of the fresh surface? That reading should be below 20% for the wood to burn well. Alternatively, have you ever tried your insert with dry wood like lumber scraps or compressed wood logs (Envi-blocks, BioBricks etc.)?

I'd PM you about this, but I'm not seeing that option...

Click on the user name and in that pop up is an option "Start a conversation".

 

[EJL923]

Pm'd fyrefly

My point was with the corrugated liner in my case, draft or cleaning isn't an issue

 

[FyreFly]

Unfortunately, the C550 is more a mid-size insert than a large one although Jotul advertises it differently. And as a flush insert it relies more on the blower although if you have a proper block-off plate and time you could also turn it off and wait for the masonry to heat up. That heat will then slowly be released into your home.

It will heat up the masonry but, unfortunately, the warmest part (the bottom back half of the chimney) faces the inside of the garage, which is unconditioned and probably wicks away most of that radiant heat.

Now, leaving the air control wide open to get a clean burn sounds like a wood issue. For how long has the split firewood been stacked in a sunny and windy spot? Did you ever measure its internal moisture content by splitting a few pieces in half and pressing the pins of a moisture meter in the center of the fresh surface? That reading should be below 20% for the wood to burn well. Alternatively, have you ever tried your insert with dry wood like lumber scraps or compressed wood logs (Envi-blocks, BioBricks etc.)?

I guess you missed the last bit of my response above... I was using liberty bricks in a 5-1 ratio and the wood was well-aged (though probably not in an optimum spot as the stacks back against a wooden fence)... but I'll pick up a moisture meter to see if I can't rule out that issue. Thanks for the suggestion.

Click on the user name and in that pop up is an option "Start a conversation".

Thanks. Never used that method to send a PM before.

Anyway, didn't mean to hijack angryhippie's thread... but before I dropped the cash on a new smooth double wall liner I was hoping to get some reassurance that I'd probably see significant improvement and glowing reviews about how much easier they were to clean. Not exactly feeling that vibe, so for now I'll get on with this first cleaning, assess the creosote, and pick up a moisture meter to be sure the wood I am using is dry enough. If I'm not seeing anything unusual there I'll continue to look into changing the liner.

 

[Grisu]

I guess you missed the last bit of my response above... I was using liberty bricks in a 5-1 ratio and the wood was well-aged (though probably not in an optimum spot as the stacks back against a wooden fence)... but I'll pick up a moisture meter to see if I can't rule out that issue. Thanks for the suggestion.

Sorry, yes, I must have missed it. The bricks are dry so wet wood is not the issue. That suggests it could be draft related although I have a hard time believing it could be the type of liner unless it was installed incorrectly. Did you have a chimney sweep take a look at it? You can search for one here: http://www.csia.org/search

Would you consider your house rather airtight? You can test whether that is part of the problem by cracking a windows close to the stove and see if that improves draft.
Are you measuring the insert's temps (e. g. with an IR thermometer)? How hot does it get? Could you tell us more about how you are operating the insert?

If you have not done so yet a block off plate will help tremendously with the heat retention: https://www.hearth.com/talk/wiki/make-a-damper-sealing-block-off-plate/
Same should be true for putting some insulation behind the insert if there is still enough room: https://www.hearth.com/talk/threads/finally-got-around-to-insulating-my-fireplace.75755/

 

[FyreFly]

Sorry, yes, I must have missed it. The bricks are dry so wet wood is not the issue. That suggests it could be draft related although I have a hard time believing it could be the type of liner unless it was installed incorrectly. Did you have a chimney sweep take a look at it? You can search for one here: http://www.csia.org/search

I have not had a sweep look at it. At the end of the season I tried getting two sweeps out using some Living Social deals. One never responded after being contacted and the other responded saying that they didn't sweep inserts. I gave up and decided I'd just clean it myself and bought a soot-eater. Still have a Living Social credit I haven't used.

Would you consider your house rather airtight? You can test whether that is part of the problem by cracking a windows close to the stove and see if that improves draft.

My house is pretty air-tight. I had a blower test done as part of a home energy audit and I didn't qualify for any of the rebates going on because it was rated pretty well. And it's probably going to get tighter as I'm prepping to clear out my old attic insulation, foam seal all cracks, and put down 18 inches of cellulose.

Are you measuring the insert's temps (e. g. with an IR thermometer)? How hot does it get?

The gun I have doesn't measure that high (it's more for just finding cold spots in a house). I did order a magnetic thermometer, but I suspect I will have a hard time finding some place to put it on the insert to get anything accurate. I figured it would be a data-point I could work with though.

Could you tell us more about how you are operating the insert?

I usually use 4-5 bricks, a medium sized piece of wood, and half a starter stick to get things started. I have the door cracked through the start process and when it gets hot enough to turn on the blower I add some fuel and close it up (air-control is fully open). I probably ending up adding 3-4 bricks an hour and a piece of wood to keep it going... but find lowering the air-control just seems to make for inefficient burns and the window starts to get dirtier more quickly. Blower is usually running at least 60-70%.

If you have not done so yet a block off plate will help tremendously with the heat retention: https://www.hearth.com/talk/wiki/make-a-damper-sealing-block-off-plate/
Same should be true for putting some insulation behind the insert if there is still enough room: https://www.hearth.com/talk/threads/finally-got-around-to-insulating-my-fireplace.75755/

Those look like really interesting projects. I've got a long list of projects to work on right now... but I will add these.

Thanks for the ideas.

 

[Grisu]

My house is pretty air-tight.

Then try the trick with the cracked window at least once. If that remedies your problems with lowering the air you know what's causing it. The standard fix would then be to install an outside air kit (OAK) but that gets tricky with an insert. Maybe drilling a hole from the garage into the back of the fireplace would be an idea. As an alternative, you could try extending the chimney with some class A pipe. It is possible that this would improve draft already enough. As a test, you can put 3 ft of cheap stovepipe on top of the chimney on a quiet day and see if that helps before going for the expensive class A.

I usually use 4-5 bricks, a medium sized piece of wood, and half a starter stick to get things started. I have the door cracked through the start process and when it gets hot enough to turn on the blower I add some fuel and close it up (air-control is fully open). I probably ending up adding 3-4 bricks an hour and a piece of wood to keep it going... but find lowering the air-control just seems to make for inefficient burns and the window starts to get dirtier more quickly. Blower is usually running at least 60-70%.

You may turn on the blower too early and on too high. Those modern inserts need high enough operating temperatures to burn cleanly and efficiently. A thermometer will certainly help a lot in determining if you are getting it hot enough. I would try a burn without turning the blower on. Once you have a good fire going, reduce the air a bit until the flames get slow (lazy). Wait a few minutes for the fire to get stronger again, then cut down the air a bit more and so on. With good draft and your dry fuel the final setting should be between 1/4 open and fully closed. At that stage you can turn the blower on but I would leave it on low for a while. You should see a lot of flames in the top of the firebox who seem to come out of the burn tubes there.

A little sooting on the glass is nothing to be concerned of and some of it will burn away soon anyway. You could also suffer from leaky gaskets. Hold a dollar bill over the insert door frame, close the door and pull on the bill. It should only come out with clear resistance without tearing it apart. If it slips through easily you should replace the gasket. Also, the window glass should not move when you try to push it to any side or your windows gaskets are failing.

 

[FyreFly]

Then try the trick with the cracked window at least once. If that remedies your problems with lowering the air you know what's causing it. The standard fix would then be to install an outside air kit (OAK) but that gets tricky with an insert. Maybe drilling a hole from the garage into the back of the fireplace would be an idea.

I thought about this... but the back of the fireplace goes into my garage and I really didn't really want to pull more cold air in there (there is plumbing in there and rooms above it). I could see drilling a hole and then piping to a vent outside the garage though... I would have to think about that.

As an alternative, you could try extending the chimney with some class A pipe. It is possible that this would improve draft already enough. As a test, you can put 3 ft of cheap stovepipe on top of the chimney on a quiet day and see if that helps before going for the expensive class A.

It's a two floor house... I think the height of the chimney should be sufficient.

You may turn on the blower too early and on too high. Those modern inserts need high enough operating temperatures to burn cleanly and efficiently. A thermometer will certainly help a lot in determining if you are getting it hot enough. I would try a burn without turning the blower on. Once you have a good fire going, reduce the air a bit until the flames get slow (lazy). Wait a few minutes for the fire to get stronger again, then cut down the air a bit more and so on. With good draft and your dry fuel the final setting should be between 1/4 open and fully closed. At that stage you can turn the blower on but I would leave it on low for a while. You should see a lot of flames in the top of the firebox who seem to come out of the burn tubes there.

Good information.

As for turning the blower on too early, I usually have the blower on "Auto" so it comes on at temperature set by the manufacturer. If I bypass that, is there a goldilocks temperature range I should be looking for?