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

[yonny33]

I'm contemplating doing this job myself.
We're having a new log burning stove inserted into our old open fireplace here in Uruguay.

The liners are all 1 meter rigid tube types 100cm. The height of my flue is about 6meters.

Now the large concrete top is shared with the neighbor.
I thought about 2 options.

1) grind a hole (150-160mm) in the top above my flue to insert the liner and top it off with a plate and hat.

2) Cut the concrete top down the middle, remove it, and fix the top plate directly on the sides of the chimney walls sealing it better. I'll have better access for cleaning in the future if removed.

What do people suggest?

This guy had a neat trick to lower the tubes. But I think there is enough space in my large fireplace to feed them up vertically.

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Thanks!

 

[gthomas785]

How hard would it be to lift off the concrete cap, drop the liner, then put it back. You might want to set the cap 1 brick higher when you replace it.

 

[yonny33]

Probably a 2 or 3 person job to lift it off. Also shares the neighbors chimney so that's not an option. I need the liner to protrude higher and a wide wind rain top as we're on the coast. Sideways torrential rain can enter easily.

Thinking of grinding a square hole over the flue. Then slide the liner up. Put a sheet of metal around it then seal up the sides with new bricks and mortar. Or cut my section off completely.

 

[gthomas785]

Have you talked to your neighbor about it? Do they use their chimney? By the way generally when you have 2 adjacent flues they should be at different heights to prevent downdrafting of one smoke into the other.

If you can't modify the other side, then I guess cutting the cap in half is your only option. Unless you can somehow pull the liner up from below and secure it without removing the cap, but it looks pretty tight to work in there.

 

[yonny33]

Hi
Yes had a chat with her. She's just separated and has 2 kids to support so her finances are are not great. I'd rather leaver her side in tact. She does use her fireplace frequently in winter.
Yep been mentioned before that it was badly designed. Made that way purely for asthetic reasons.

Spoke with a technician yesterday and he said he would normally make a perforation in the top to allow the liner to slide through the top of the concrete and then seal the opening. This way the neighbors chimney is also at a different height

I'm more inclined to go that way. Get my grinder out and make a perforation about the size of the flue. I can then access other from above to clean etc while not having to remove the entire piece

It will need a very good hat/rain cover so needs to come through the top

 

[gthomas785]

Sounds like a plan just make sure to flash/seal properly where the pipe comes through the cap

 

[yonny33]

Sounds like a plan just make sure to flash/seal properly where the pipe comes through the cap

What kind of seal/flash would you recommend?

 

[gthomas785]

If I understand your plan correctly, I think you could use the regular flashing for attaching a liner at the top of a chimney. Looks like this.

 

[bholler]

Just a regular liner top plate caulked down like you would ontop of a chimney is all you need ontop. And one ontop of the actual chimney under the concrete cap

 

[gthomas785]

By the way, will the liner be insulated? I don't know whether it's required in your location but I would highly recommend it. It will improve draft and safety, and reduce creosote formation.

 

[yonny33]

If I understand your plan correctly, I think you could use the regular flashing for attaching a liner at the top of a chimney. Looks like this.

View attachment 275815

So the narrow part would fit a 150mm liner for example ? Normally here they provide a simple flat galvanized sheet for the flashing.

Would I use high temp silicone or cement to bond the plate to the concrete base?

The liner will not be insulated. They don't have those here. Not even flexible liners unfortunately.
The flue is well built.

 

[gthomas785]

Yes you need the right size flashing to match the size of the liner. And as bholler mentioned you will need 2 of them to make it weatherproof in this case. Caulk it down around the edges and you're done.

 

[yonny33]

Sorry noob question.
Caulking? You mean filling with a cement mixture?

Yes probably plan to actually seal the side holes under the top with new bricks and mortar possibly
Or a steel plate cut to size. I have a decent grinder with discs for metal and concrete.

 

[yonny33]

Just looked up caulking.

So just a waterproof flexible sealant I understand. Preferably high t temp sealant

 

[yonny33]

What kind of sleeve liner do I need for the final part between the stove and rigid liner?
150mm 100cm sections.

I can't imagine trying to fit a rigid liner to the exact length and sealing it at the top, obviously needs some sleeve between the stove and start of the liner to have some adjustable movement there I believe. Correct me if I'm wrong.
I haven't seen anything as such in the kits here yet. Need to investigate a bit more.

 

[gthomas785]

I don't know what you have available but what we use here is called "connector pipe" or just stove pipe. It comes in sections, crimped on one end and you can cut the other end to length with a hacksaw.

 

[yonny33]

Yes we have these sections with a crimped end.

Is the stove connector pipe slightly different with a very slightly wider diameter to slide over the liner for final adjustment then sealed?

Many thanks

 

[gthomas785]

I don't know it depends on your liner. I would just cut the last piece a little long, then test fit and adjust as necessary until it's snug.

Also it doesnt have to be perfectly sealed, since the chimney draft will create negative pressure inside the pipe and prevent smoke leakage. However, a tight fit is desirable.

 

[yonny33]

Just asked a local manufacturer about a stove slip connector pipe.
They had never even heard of it before. Like the flexible liners here in Uruguay - no knowledge of them.
Bit behind the times I believe!

 

[gthomas785]

Slip connectors are common with double wall pipe, but I've never seen/used one with single wall. I would just cut the pipe to fit and screw it all together.

 

[bholler]

Slip connectors are common with double wall pipe, but I've never seen/used one with single wall. I would just cut the pipe to fit and screw it all together.

We use them with single wall all the time as well. Even stainless liners at times

 

[gthomas785]

We use them with single wall all the time as well. Even stainless liners at times

Ok I guess I stand corrected, I had heard of them for single wall but I didn't know they were that common.

 

[begreen]

So just a waterproof flexible sealant I understand. Preferably high t temp sealant

Just looked up caulking.

So just a waterproof flexible sealant I understand. Preferably high t temp sealant

The temp on the outside of the chimney pipe at that location is not that high. Use a good quality silicone adhesive sealant that bonds well to metal. I like GE Silicone II, but there are probably are others that also work well.

 

[yonny33]

I am rather confused about how to install the part that comes out of the top of the chimney.
Is it common to install a sleeve with insulation for the part that is exposed to the exterior air? The kits here come with these wider sleeves and reducer.

But I'm not sure how to attach the wider sleeve to the flue exit. The kits here come with just a flat piece of steel without any cutouts or any collar to attach it to.

Also still going over in my head whether to cut a hole on the top of the concrete top or just cut the whole thing in half and removed it, then using the steel plate to cover the 300mmx300mm chimney flue. But then if the stell plate does not come with any collar, how is the wider sleeve attached to that.
Seems to be a missing part of the puzzle here.

Further suggestions would be greatly appreciated. I want to make sure this is done very well as I do not have any confidence in the fitters here.

I usually end up doing my own DIY jobs after so-called pros leave me disappointed. Like the sweepers, I had in. Awful job done. Loads of soot left and left the 1-meter section uncleaned above the part of the flue with the concrete steel bars across where the top floor meets the flue.
(I'll be removing these with my grinder and finish the sweep job))

Standard kit here. See just a flat plate for the flashing. How is the wide sleeve attached with no collar or clamp? I've seen in a youtube they just rest it on the ceiling plate but in my case I do not need the sleeve all the way up the 5 meter chimney, just the liner. Also 5 metres of sleeve with collapse any ceiling plate.

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Thanks!

 

[yonny33]

Had some further discussions and we've decided just to have the 130mm liner up to the level of the flue structure below the original concrete top. Will place a flashing across the opening to seal it.