Suggestions needed to feed a rigid tube liner above the roof with a flat concrete top.

[gthomas785]

Yep looks that way now.

I would like to thank you for all your advice. Really cleared some areas up for me where I was struggling.

Now just got to design the supports/clamps. I'd like to have one just between the main 0.5m black stove pipe and where the liner starts. I'll be choosing the rear exit pipe on the stove (have both options).

1 curved 90 degree bend at the rear (has a removable plate for cleaning) and then attached to the thick 2mm black stove pipe, which will just go through my closure plate and then have the liner start there. So will have some extra support just above the closure plate (which I'll make removable).

That's the plan anyway.

Possibly some strong brackets on the wall with a 130+mm jubilee clip or home made clamp from some 23cm galvanized piping I have leftover.
Jubilee clip holding some L shaped supports around the pipe that will rest on a couple of strong shelf brackets attached to the wall. Have that kind of design in my mind.

Liners are commonly secured at the top.

Do you think you could make something like that work? Otherwise you're looking at rigging up some brackets lagged into the masonry

 

[yonny33]

Normally the insulation would get encased in a stainless steel mesh sleeve that protects it and keeps it intact.

Stainless Steel Mesh

Stainless Steel Mesh: Ideal for chimneys with decorative stone or brick tops, offering protection when traditional chimney caps can't be installed.

www.lindemannchimneysupply.com

Thanks.

I have a plate at the top but is rather thin I realized. I will put a support into the masonry near the lower part of the flue and possibly a clamp at the top like in the picture there but will make sure the weight is mostly on the support at the bottom but not on the stove.

Again will have to be homemade as they just seem to install the pipes from bottom-up and have the weight on the stove as 95% are top exit stoves. I ask for certain parts and they respond with ' they have never heard of these parts before'.


like the slip connector and flexible liner also

Started a conversation last night from the seller of the pipes, after a couple of questions he just stopped replying. It was getting too technical as they just push the pipes up from below, without any rivets/screws and without any insulation, except for the outer part.

Swaying more towards the rock wall now as it has the covering on it to keep all in place.

 

[gthomas785]

Can you get a clamp that's long enough to span the chimney and rest on the masonry under the concrete cap? I know you said you were planning to seal off the holes under there, so maybe leave enough of a notch in whatever you fill it with to allow the clamp to sit there. That would hold the weight of the liner and no need to support it from below. Just an idea.

 

[yonny33]

Can you get a clamp that's long enough to span the chimney and rest on the masonry under the concrete cap? I know you said you were planning to seal off the holes under there, so maybe leave enough of a notch in whatever you fill it with to allow the clamp to sit there. That would hold the weight of the liner and no need to support it from below. Just an idea.

Could be yes.
Would need to make a couple of slots in the existing outer sleeve though. Possibly a long steel rod going across.

I've added the sleeve and cowl as a mock-up right now and to test its waterproofing for the storms forecast this week.
We had some water ingress with the original fireplace due to the coastal winds and rain so needed to test it before adding the liner/stove and hearth etc. Last thing I wanted was to install it all and have drops of water coming down maybe not even noticed.

Thinking back I should have put some extra bracing underneath across. I could still do that by drilling a hole just under the plate through the mortar and pushing steel rods across!

 

[gthomas785]

Yeah looking at those images I would try to put a clamp above that lower plate. The plate is probably strong enough to hold the liner. but if not, get a longer clamp to reach the edges of the plate where it's resting on the bricks. I think that's much easier than trying to secure it from below.

 

[yonny33]

Yeah looking at those images I would try to put a clamp above that lower plate. The plate is probably strong enough to hold the liner. but if not, get a longer clamp to reach the edges of the plate where it's resting on the bricks. I think that's much easier than trying to secure it from below.

I may just drill a hole through the masonry under that plate and slide a steel rod across to give it extra support. easy enough I think.
Or cut some more sheet metal and lay across which I do have.

 

[yonny33]

Just found these brackets that might work well with a wide jubilee clip perhaps. Possibly with 4 around to spread the weight evenly. Ikea bracket parts left over. Sure I've got more

 

[gthomas785]

I may just drill a hole through the masonry under that plate and slide a steel rod across to give it extra support. easy enough I think.
Or cut some more sheet metal and lay across which I do have.

Just don't block the path for the liner!

 

[begreen]

It looks like the liner is going in a larger metal sleeve. Is this correct? If so, that will protect the insulation jacket. Just don't use screws to attach the outer jacket pieces, use pop rivets instead.

 

[yonny33]

Also I think once I finish installation I will cover up the side chimney holes under the concrete top with some galvanized steel sheeting. Thought about bricking them up but would like access in case I need access to the plate. These holes covered up will prevent any sideways rain from getting in there.

But I'll use screws for the reducer and cowl because these will need to be removed easily for cleaning. Unless it's easy to remove rivets. I'll be a rivet first-timer here.

 

[yonny33]

It looks like the liner is going in a larger metal sleeve. Is this correct? If so, that will protect the insulation jacket. Just don't use screws to attach the outer jacket pieces, use pop rivets instead.

Yes that's right, 23cm wide sleeve. Once I have the 13cm liner through I will fill this will granular rock wool that I have already.

I'll use rivets as suggested thanks but as mentioned above the reducer and cowl will need to be easily removable so screws with some sealant?

 

[begreen]

What is the clearance from the outer liner to the nearest combustible?

As described, I think I would wrap the inner liner with 2 cm thick ceramic wool, using stainless wire to hold it in place (maybe over a full band of the aluminum tape?) spaced about 40 centimeters apart and I would skip the rockwool granules.

 

[yonny33]

What is the clearance from the outer liner to the nearest combustible?

As described, I think I would wrap the inner liner with 2 cm ceramic wool, using stainless wire to hold it in place (maybe over a full band of the aluminum tape?) spaced about 40 centimeters apart and I would skip the rockwool granules.

The existing brick flue is 30cmx30cm. But this has been used for the last 12 yrs. Would this be considered as combustible?

Could try and slice some of the 50mm rock wool down to 20cm or so.
The granules are just for the top part sleeve.

The rock wool panels with aluminum wrapping were intended for the 1 meter sections.

 

[begreen]

This sounds very well protected with insulation on the liner, then an outer liner, then an air gap, then the brick. I would not bother with the rockwool granules. That is bound to be a messy process.

 

[begreen]

The existing brick flue is 30cmx30cm. But this has been used for the last 12 yrs. Would this be considered as combustible?

No, but the chimney should be thoroughly cleaned first. If the chimney brick touches wood, that is the first combustible. Does it?

 

[yonny33]

No, but the chimney should be thoroughly cleaned first. If the chimney brick touches wood, that is the first combustible. Does it?

There is no wood.
I had it cleaned 'professionally' then gave it another clean myself from above and below as I was not that happy with the work done.
There was quite a lot of stage 2 creosote.

 

[begreen]

There is no wood.
I had it cleaned 'professionally' then gave it another clean myself from above and below as I was not that happy with the work done.
There was quite a lot of stage 2 creosote.

If this is a cement or adobe house then there is no need to overkill. The insulation is primarily for safety. With no combustibles in contact or close to the chimney, this is a non-issue. You can skip the insulation or just pour the rockwool granules around the inner liner if desired. If you do pour the granules, the bottom of the outer jacket must be sealed to the inner liner or there will be messy rockwool granule leakage.

 

[yonny33]

If this is a cement or adobe house then there is no need to overkill. The insulation is primarily for safety. With no combustibles in contact or close to the chimney, this is a non-issue. You can skip the insulation or just pour the rockwool granules around the inner liner if desired. If you do pour the granules, the bottom of the outer jacket must be sealed to the inner liner or there will be messy rockwool granule leakage.

I understood from the other poster that the liner was to prevent creosote buildup, avoid condensation, and increase the efficiency of the liner/stove.
Essential, I understood even with brick and mortar chimneys with no combustibles.

 

[gthomas785]

You absolutely want insulation on that liner. There is no clay liner in there.

Multiple reasons. The first is it is code here unless the chimney has a 1" gap from the house structure. The second reason is that without any clay liner there are less layers of protection between the very hot flue liner and the combustibles of the house. The third reason is that insulation will keep the flue gases hotter. This last reason really helps improve draft and by keeping the flue gases hotter it can really help keep creosote buildup down as long as dry wood is being burned.

If this is a cement or adobe house then there is no need to overkill. The insulation is primarily for safety. With no combustibles in contact or close to the chimney, this is a non-issue. You can skip the insulation or just pour the rockwool granules around the inner liner if desired.

Insulating the liner is always a good practice and will improve the performance of the chimney especially with so much dead air around it.

However, without any wood around the chimney, it is not a safety issue to skip the insulation. You will have cooler flue temps and more creosote buildup as mentioned before. I would still insulate it if at all possible.

I guess we Americans are not used to houses with no wood in them!

 

[yonny33]

Insulating the liner is always a good practice and will improve the performance of the chimney especially with so much dead air around it.

However, without any wood around the chimney, it is not a safety issue to skip the insulation. You will have cooler flue temps and more creosote buildup as mentioned before.

I guess we Americans are not used to houses with no wood in them!

yeah never understood the trend for the wood houses there especially with the tornadoes and hurricanes.

Always been in solid double wall brick houses in the UK. 110 mph winds no problem!
Even 1-meter thick slate wall houses like my late grans in Wales. Dates back to about 1500 I think

Just a thought - How heavy is the 50mm rock wool liner? Thinking about the overall weight for the top clamp

 

[gthomas785]

It's an abundant building material (or was, until this year I guess. Have you seen the lumber prices lately?!)

Anyway, I don't think a typical insulation blanket adds much weight to the liner. Let's see, the website says it is 40 kg/m^3,

0.012 m thickness x 0.4m circumference x 5m length, is 0.024 m^3, so about 1 kg.

 

[begreen]

Insulating the liner is always a good practice and will improve the performance of the chimney especially with so much dead air around it.

Thus the rockwool granules. This appears to be the standard procedure for this circumstance. No point in fighting the river. Burning clean dry wood and not smoldering the fire should keep creosote buildup at a minimum.

 

[gthomas785]

Thus the rockwool granules. This appears to be the standard procedure for this circumstance. No point in fighting the river. Burning clean dry wood and not smoldering the fire should keep creosote buildup at a minimum.

My understanding was they only insulate the top part above the masonry with the rockwool granules, and the rest of the run is a single wall pipe in free air.

 

[begreen]

Is the outer liner just at the top part of the masonry chimney? How far down does it go?

 

[yonny33]

Is the outer liner just at the top part of the masonry chimney? How far down does it go?

Yes just the top, from the plate through the concrete top and extending about 50cm in total height not including the cowl.