Ceramic vs metal flue liner

[MortarThePoint]

The chimney has started going up which is some of the first above DPC brickwork so nice to see. It's thrown open a whole host of questions though, one of which is how to line the chimney (plans at the bottom). I see two main options:

 

• Ceramic (inc Pumice) flue liner:  Tubular sections that are stacked on top of a concrete (?) base plate and sealed together. You surround the sections with either granular or fibre insulation. Very much built in to the chimney and needs to be done as the chimney goes up. I expect this would cost around £900 for 200mm x 7m. Here's a video that shows the concept:  https://youtu.be/VVRhrdjoFbw

 

 

 

• Corrugated metal flue liner tube: available in 316 (15 years) or better 904 (30 years) grade stainless steel this costs about £340 for 200mm x 7m. I think these are double wall to warm up faster and I guess would just hang down the chimney from the top? It's certainly the cheapest choice, but also seems like the choice that is easiest to go back on and change to another approach at a later if wanted and doesn't need to be built in as the chimney goes up as far as I can see.

 

       

 

We had planned to use a stove as I was under the impression that open fires were no longer allowed, but various suppliers are suggesting they are. If you had an open fire, I think you then need a gather that sits above the fire basket and would then attach to the flue liner, though I am uninformed there so if anyone has done this please share some knowledge.

 

What approach did you choose?

 

 

 

[Onoff]

12 minutes ago, MortarThePoint said:

I think these are double wall

 

A safety thing I think to guard against fume leakage?

[scottishjohn]

is this for a gas fire or a log burner --if log burner i would go ceramic --could be a lot hotter than you think especially when it catchs fire from all the resin inside it in years to come 

and ceramic life will be same as the house

 

[MortarThePoint]

8 minutes ago, scottishjohn said:

is this for a gas fire or a log burner --if log burner i would go ceramic --could be a lot hotter than you think especially when it catchs fire from all the resin inside it in years to come 

and ceramic life will be same as the house

 

It would be for a log burner

[nod]

We went for a built in 

BC would only allow a couple of foot per day with inspections and photos to make sure everything was sealed 

[Onoff]

Get the flue right. When I was a kid our next door neighbour did his own and the parents and 2 kids were all hospitalised with CO poisoning. 

[scottishjohn]

1 hour ago, MortarThePoint said:

We had planned to use a stove as I was under the impression that open fires were no longer allowed, but various suppliers are suggesting they are.

my Tf house was built with an open fire ,which I had to line only because i changed to closed in unit ,then to a baxi bermuda gas fire and back boiler -which has now gone and i,m ASHP

I,ve been here 30 years  so it was built with an external fyfe stone chimney , but if an open fire you just build a proper chimney  

[MortarThePoint]

25 minutes ago, Onoff said:

Get the flue right. When I was a kid our next door neighbour did his own and the parents and 2 kids were all hospitalised with CO poisoning. 

 

Definitely want to avoid that!

[Onoff]

1 minute ago, MortarThePoint said:

 

Definitely want to avoid that!

 

They went to bed not realising they were coming down with the flue..

[MortarThePoint]

19 minutes ago, scottishjohn said:

my Tf house was built with an open fire ,which I had to line only because i changed to closed in unit ,then to a baxi bermuda gas fire and back boiler -which has now gone and i,m ASHP

I,ve been here 30 years  so it was built with an external fyfe stone chimney , but if an open fire you just build a proper chimney  

 

Lovely stone.

 

A proper chimney may be beyond the scope of things at this stage so a flue liner is likely the only option. I suspect that means we have to have a log burning stove.

[ProDave]

Our previous house with a brick chimney used the clay ones in your right hand picture and the gap between the liner and the masonry was filled as they went with vermiculite.

 

You then fit a closure plate at the bottom to seal around a flue pipe from a WBS

[MortarThePoint]

Sounds like people prefer the ceramic approach. Is there a specific reason to not like the corrugated metal approach? I know it needs replacing, but that would be after ~30 years. It's a lot easier to install if I understand correctly.

[dpmiller]

I went with ceramic

 

https://www.schiedel.com/uk/products/ceramic-system-chimneys/swift-air/

 

which also neatly looks after supply air too. A complete system inc the outer blocks etc was around the money the OP mentioned.

[Declan52]

Old fella told me years ago to make sure the chimney is built right. If it doesn't draw smoke it will definitely draw tears was his moto.

Ceramic all the way. 

I thought them metal flue kits are more for relining a ceramic flue. Twin wall is used if your not building an actual chimney.

[MortarThePoint]

18 minutes ago, dpmiller said:

I went with ceramic

 

https://www.schiedel.com/uk/products/ceramic-system-chimneys/swift-air/

 

which also neatly looks after supply air too. A complete system inc the outer blocks etc was around the money the OP mentioned.

 

That's a cool system and solves the air supply nicely

[Cpd]

1 hour ago, Declan52 said:

I thought them metal flue kits are more for relining a ceramic flue. Twin wall is used if your not building an actual chimney.

Also used to reline any old chimney, ceramic or not. If starting from scratch then ceramic all the way. 

[PeterW]

The stainless ones are designed for retrofit - not sure how you’re getting to £900 as I use the Dunbrik concrete ones and they usually end up at about £450 for a 2 storey house minus the pot. 
 

You will have to build a full brick or block outer to line with a stainless liner so you’re saving nothing in reality. 
 

Do it right and do it once - ceramic or concrete will last the life of the house. 

[dpmiller]

Scheidel quote including the rockwool insulation, the actual blocks and pipes, adhesive etc. It's really plugandplay (especially if you're rendering the blocks directly, we built a skin of standard blocks around the system blocks) even if the blocks are *heavy*...

[MortarThePoint]

17 hours ago, dpmiller said:

Scheidel quote including the rockwool insulation, the actual blocks and pipes, adhesive etc. It's really plugandplay (especially if you're rendering the blocks directly, we built a skin of standard blocks around the system blocks) even if the blocks are *heavy*...

 

So did Scheidel prepare a design for your chimney? I'm getting a design prepared by Dunbrik, but I'd like one for the Isokern system by Scheidel as well.

[dpmiller]

2 hours ago, MortarThePoint said:

 

So did Scheidel prepare a design for your chimney? I'm getting a design prepared by Dunbrik, but I'd like one for the Isokern system by Scheidel as well.

 

Yes, they'll quote by height with whatever base starters or lintels, pots etc. Check the price between Isokern and Swift, too.

[sean1933]

On 15/08/2020 at 08:56, MortarThePoint said:

The chimney has started going up which is some of the first above DPC brickwork so nice to see. It's thrown open a whole host of questions though

 

 

I'm having a similar dilemma at the moment so am interested to learn which route you chose in the end?

 

We have a slightly different and unique setup in that our stack is fully external and 1.8m wide with a BBQ/fire on the outside. The stack has therefore been split in 2 to serve both the BBQ/outdoor fire and internal woodburning stove. Builder started leading me down the path of a liner as its easier and faster to fit than clay blocks (as BBQ is occasional use) but now I'm questioning it having read this thread. 

 

My current plan is to use a 150mm twin wall flue inside one side of the stack (for logburner, having been sleeved through the cavity wall), and a 350-400mm steel liner on the other side to service the BBQ/fire. Any input greatly welcomed!  

[Onoff]

The FiL has a dual fuel set up on the one stainless steel flue. An oil boiler and adjacent wood burner feed this same flue. He's of an age where he'll burn anything from pallets to MDF and household rubbish, plastic bags etc despite repeatedly being told not to. (He doesn't like using the oil). 

 

On more than one occasion the resinous build up inside the stainless flue has caught fire. 

[MortarThePoint]

We've gone the Isokern route. It is quite expensive compared to just a corrugated steel flue liner, but I was told by many that you can't just have a corrugated steel flue liner on a new build. There is a lot to be said for a simple straight run.

 

Cool arrangement you are having with the BBQ. I always liked the idea of a pizza oven built in to the wall with a door in to the kitchen and a door on to the patio. That got forgotten about when the realities of the building arrived, but I still think it would be cool.

[PeterW]

19 hours ago, sean1933 said:

My current plan is to use a 150mm twin wall flue inside one side of the stack (for logburner, having been sleeved through the cavity wall), and a 350-400mm steel liner on the other side to service the BBQ/fire. Any input greatly welcomed!  

You can’t use twin wall inside a stack - you have to be able to inspect the joints and connectors. You can use 150mm corrugated liner for the BBQ but it’s really a bit pointless if you’re building a brick chimney anyway as you may as well do it once and do it with a concrete or pumice liner system.  Side by side is dead easy to do, and just dropping the segments on as you go with the sealant will have it built in no time. No need for that bigger size either - just do both with 200mm Dunbrik and they will be good for the life of the house. 

[sean1933]

On 24/11/2020 at 19:50, PeterW said:

You can’t use twin wall inside a stack - you have to be able to inspect the joints and connectors. You can use 150mm corrugated liner for the BBQ but it’s really a bit pointless if you’re building a brick chimney anyway as you may as well do it once and do it with a concrete or pumice liner system.  Side by side is dead easy to do, and just dropping the segments on as you go with the sealant will have it built in no time. No need for that bigger size either - just do both with 200mm Dunbrik and they will be good for the life of the house. 

 

Hi Peter - I am heavily leaning towards the isokern idea for the main logburner for longevity etc. The chimney is however large enough that a slender person could probably just about climb up inside to inspect any twin wall connections. From a labour etc perspective I considered Isokern DM is probably the way to go rather than Dunbrik as each side of the chimney is 700x800 internal so would need huge amount of vermiculite to insulate and I would therefore probably need to build another smaller stack inside the larger stack for stability (flues cant free stand I believe) and to encase the vermiculite - sounds labour intensive. Not to mention the added weight of an entire new internal stack that wasn't account for by the SE (thank you Architect....).

 

Perhaps an alternative might be 200mm Dunbrik boxed in at 1 corner of the stack (so only 1 extra run of bricks and flue required), does this sound more sensible? the logburner specs a 150 flue so I assume going bigger isnt a problem?

 

 

With regards to the larger BBQ chimney I calculated the size of flue required for an open fire as per building regs... as the opening is something like 1350x825mm, a 350 flue is broadly in the remit for what size is suggested for good draw. In reality I believe 400mm would be better but you cant get a liner in that size unless I go concrete at huge expense so I figured as its outside anyway it wouldnt be the end of the world if all the smoke didnt go up the flue.  Or do you consider I'm going over the top?

 

I am just trying to avoid what was a 'nice to have' BBQ idea not costing me the earth in liners!

 

Edited November 26, 2020 by sean1933