6 inch flex liner question

[woodhog73]

I've got a new insert. There is a 6 inch flex liner with a straight shot no real big bends in it, running inside a clay flue and cement block chimney. One story tall. No insulation was used because it's inside the existing clay flue.

I've burned roughly a cord of dry oak and maple in it so far and it still appears clean. Some creosote on the rain cap but not so much anywhere else that I can tell. I haven't run a brush in it yet. Couple of questions.....

1) do these flex liners tend to have more or less creosote build up ? It's got ridges inside so it's not smooth. Wouldn't creosote stick to it more on the ridges? I read somewhere that the flex liners expand and shrink with heat and creosote doesn't stick as much ? Not sure but it seems clean and no creosote is falling inside the stove ( new EPA stove insert burns hot and clean)

2) can someone recommend a good brush ? I've never cleaned a flex liner. Do I just run the brush all the way down to the insert , and let the brush stick into the insert, then pull it back up? Do the brushes fit tight in these 6 inch liners ? Any tips on cleaning is appreciated.

Thanks !

 

[Core]

I have a similar set up but my liner is insulated. I burned approximately 5-6 cords approximately the past 2.5 winters and cleaned my liner this fall from the bottom up.I believe the liners attract less creosote because they draft faster vs large square clay liner that takes time to heat up. There was maybe a cup of creosote at the bottom of my insert. I used the soot eater system which worked well for me. The reason why I had so little creosote is two year dry wood stacked and covered properly, hot fires, and common sense burning learned here. If you clean from top down you will have to clean off baffle where brushed debris will fall on top of.

 

[woodhog73]

Interesting your liner is insulated. I asked about it since I figured insulating would be a good thing but the company said the clay flue liner inside the masonry chimney provides a layer of insulation and safety.

I've not cleaned it yet but it looks like I need to remove one of the top burn tubes inorder to remove the top baffle/ top ceiling piece inside the firebox so I can scoop out the creosote. Unless I stick a shop vacuum up there to get to it.

So do you extend your brush all the way into the stove ? What kind of brush are you using. ?

 

[BrotherBart]

To brush the liner take the baffle out of the top of the 3100i first. If you don't you risk busting the baffle when brushing. Expensive. Then when you brush you brush the accumulation down into the firebox and then replace the baffle and whatever burn tubes you needed to take out to remove the baffle.

 

[Core]

what he said ^^^ about baffle. I have to remove two burn tubes and my stainless baffle to clean from insert up to chimney cap. it can be a pain in the ass to remove baffle but I would need to set up staging to clean my chimney from top down. Google search "Soot Eater" and thats the brush system I use. I was thinking if you were brushing from top down you would not hit baffle

 

[woodhog73]

Thanks this is all great info. I was gonna mention it's a 3100i you must have seen in my other post.

I wasn't sure on correct terminology ? so I guess calling the tubes with air holes on top burn tubes, and that ceiling piece as a baffle is right.

So you have to brush your set up from the insert up? I never thought of that because my house is one story and an easy roof to walk on. I was planning on brushing from top down.

Thanks for the tip on removing the tubes and baffle piece. I was hoping I could just leave it in place and use a big shop vac to vacuum the creosote that falls. I hate the thought of those screws holding on those tubes failing with all the heat cycles and what not. There's room enough to get a shop vac hose between the ceiling baffle and where the flex liner attaches to stove. But if they break easy I don't want that . My baffle looks like fire brick material and not steel. I would think steel would be better since it is stronger.

I'll look into that brush. I suppose if I have someone looking up into the insert as I run the brush they can yell up to me to tell me when the brush is inside the insert. That way I could possibly leave the tubes and ceiling baffle on and use the shop vac. ??

One last question then I think I'm good. Do these flex liners stay in place well enough? I was surprised on mine it's only held on by 2 very small self tapping screws. I suppose no ones pulling on it so no big deal but with a brush passing through it a few times a year seems like a weak point.

Thanks

 

[bholler]

Interesting your liner is insulated. I asked about it since I figured insulating would be a good thing but the company said the clay flue liner inside the masonry chimney provides a layer of insulation and safety.

They are wrong the fact that there is clay there does not affect the requirement for insulation at all what does is wether you have the proper clearances from the outside of the chimney to any combustible materials.

I was surprised on mine it's only held on by 2 very small self tapping screws. I suppose no ones pulling on it so no big deal but with a brush passing through it a few times a year seems like a weak point.

It should be hled bu more than 2 screws especially if it is light wall which if it is ribbed it probably is. Screws dont hold in lightwall well at all.

I would remove the baffle yearly for cleaning if you don't and you ever have to pull it or the tubes the chances of those screws coming out are not very good. We also always put anti seize on them before putting them back in.

 

[woodhog73]

Bholler this makes sense. It's an exterior chimney on an exterior wall and does not pass through the attic. It's clay flue tiles inside a cinderblock chimney which is then covered in brick for curb appeal. There wouldn't be much room for insulation as the flex liner barely fit in the clay tile. I asked about removing the clay tile so we could fit insulation around the flex liner and the answer I got was that the clay flue liner was safe to burn with so that's better to leave that in than tear it out and also that the clay tile insulates heat from reaching the cinderblocks. I will say the entire masonry fire place is stone cold to the touch. Even inside above the insert the bricks go to the ceiling and stay cold to the touch.

As for the screws that's what I was thinking. But the insert only had 2 tabs sticking up to screw through and into the liner. I would have thought there should be atleast 4 places to put screws but only 2. Strange. I'll inspect the connection I guess after each cleaning. I'll have to pull the face plate off to see the connection. Where the flex liner meets the insert

Thanks for the tip on removing the baffle yearly and using anti seize , makes sense I'll do that.

 

[bholler]

asked about removing the clay tile so we could fit insulation around the flex liner and the answer I got was that the clay flue liner was safe to burn with so that's better to leave that in than tear it out and also that the clay tile insulates heat from reaching the cinderblocks.

Well if there is not the required clearance your chimney did not meet code previously and still does not now. And clay tile has very little insulating properties at all.

I will say the entire masonry fire place is stone cold to the touch. Even inside above the insert the bricks go to the ceiling and stay cold to the touch.

But what temp would it be in the event of a chimney fire? That is why the code requirements are the way they are there can be enough heat transferred through to ignite combustibles especially if they have been pyrolised from years of exposure to heat.

But the insert only had 2 tabs sticking up to screw through and into the liner. I would have thought there should be atleast 4 places to put screws but only 2. Strange. I'll inspect the connection I guess after each cleaning.

There should be an appliance adapter that has a clamp on it to attach to the liner and than that appliance adapter would be attached to the insert with screws. Screws do hold fine in the thicker stainless of the adapter.

Thanks for the tip on removing the baffle yearly and using anti seize , makes sense I'll do that.

Yeah it just avoids potential problems down the road. We pull the screws even if there is no need to remove the baffle.

 

[woodhog73]

Bholler.....thanks for your help. You certainly know much more than I do on this stuff.

As for the original chimney construction itself not up to code I wouldn't be surprised. My house is 40 years old I'm not sure what code was back then. But I made sure to go through a good dealer who has professional installers. Trust me that's why I asked about tearing out the clay flue tiles but in the end we left them. The guys installing the insert and liner have a great reputation and were certified, etc. The guy before me burned for 35 years with a stove venting into the clay liner and when I bought the house I will say the flue was spotless. So he maintained it. That said I have no idea if the flex liner itself is insulated?? I know it wasn't cheap.

As for temp during a chimney fire I hope I never find out. The fire place was an early 70s attempt at a heating device with a foot of hollow space above the original masonry fire box and some heat registers to allow radiant heat to escape that hollow space. Perhaps that helps to insulate some of the heat which is why my bricks stay cold to the touch ?

I didn't know about the adapter. I thought The flex liner is screwed directly to the tabs on the insert. However I may be wrong I was watching the install but not continuously and given the installers good reputation I'm thinking he would have used an adapter if it's required. When I run a brush through the liner, I will inspect the connection and see about putting this adapter in place if it's missing. Thanks for that info

Lastly how well do these flex liners perform ? What I mean is does creosote tend to stick less to them than clay flues? And how easy do brushes work on them?

Thanks

 

[bholler]

Lastly how well do these flex liners perform ? What I mean is does creosote tend to stick less to them than clay flues? And how easy do brushes work on them?

No creosote does not stick to them as much as it does to clay. clay is porous stainless is not so it will stick to clay much better. But if you burn wet wood or burn to cool you can still glaze them and that is not easy to clean even off of stainless.

And how easy do brushes work on them?

That depends on the liner and the brush. But because the creosote does not stick to the stainless as well you do not need the brush to be as stiff or fit as tight so it is usually easier