Builder's opening in chimney

[pilsbury]

Just removed the old fireplace as the first step of trying to install a log burner. Pleasantly surprised that the builder's opening is ample size. The arched bricks, which I'm sure are now self supporting, have a curved steel bar beneath them which I'm wondering if it offers extra support. Anyhow, it looks to me like there is a fireplace built within this opening. My initial thoughts are to just knock it out, but looking up the chimney it seems that an internal chimney extends up about 3'-4' which sits on the fireplace bricks. Is it simply this and can I remove the lot?

Top photo shows fireplace within the builder's opening, bottom photo has the front of the chimney at the top and the back of the chimney at the bottom with the sides curved up within the builders opening. You can see the start of this curve from the first picture

 

[pilsbury]

Just to add, the chimney stack is external and goes straight up for at least 3m before it gathers in for the fire in the room above. Am I correct in thinking that the narrowing of the chimney by the fire place is not gather and merely a throat that can be removed?

 

[Nige F]

As I see it you will get bricks coming away on the L. side of your flue photo, where they have been built up. The R. side is part of the original build ( I vinndicate my assumption by the presence of parging on the R.) So start removing bricks from the L. side @ the front

 

[vinn]

OP,
You will have no problems removing all the infill inside the original builders opening - remove both sides back to the arch supporting bricks.
The fireback brickwork in your pic can also be removed.
Leave the metal bar alone unless its rusted.

After doing the above send pics of the throating - how you arrange the "entrance to the flue" will depend on what kind of appliance you install.

However, you must work to the Mfr's min. opening dimensions for the appliance you want to install?

The flue in the pic is separate from the fireplace and flue in the bedroom above.

FWIW: remove the restrictor elbow and gas supply back to source if you no longer need them.
Is there a concrete or stone front hearth below the blue tiles?

 

[pilsbury]

Thanks both for your input. I've shown these pics to numerous people now and the consensus seems to be just remove the "stuff" inside the opening being careful for bricks not to drop on my head!

The metal bar also supporting the arch is in very good order. Just minimal surface rust.

I'll be installing a log burner, the particular one I've got in mind will easily fit in bearing in mind the required clearance each side and back.
For the flue, I was going to use a flexible 6" flue liner with register plate to block off the chimney opening as specified.

Beneath the blue hearth tiles appears to be concrete. They're gonna have to come up and be replaced as many are cracked.

I shall be removing the old gas outlet in due course.

 

[Doggit]

The bar was put in place to hold the arch as it was built, so could be cut out if the arch is in good condition. You can take out the bricks either side, and then the rubble, and you may find that there's more rubble behind the rear bricks as well, so you may want to put some of the bricks back in that back if it's an outside wall. If you're putting in a liner, then you'll want a closure plate rather than a register plate, and in using a liner, then the "throat" isn't so important, and as long as you can redo any bricks that drop, or need to be readjusted, then you'll be fine. Get the chimney swept as soon as possible, and use vermiculite to insulate the liner, and you'll be fine.

 

[pilsbury]

Thanks doggit. I'm gonna have a go at removing the bricks tomorrow. I'm probably gonna leave the metal bar in situ. It's a chunky piece of metal and although it may well be simply a form for when the arch was built, it doesn't look bad and will offer me peace of mind. Closure plate- you're right, just got my terms mixed up.

Why do you suggest placing some bricks back on the back wall? It is an external chimney.

I'm also keen to find out why you you suggest using vermiculite to insulate the liner. How much? Fill the entire chimney? God knows how much that will take!

 

[Doggit]

When you remove the rear bricks, you may well find rubble behind them, and then only a single skin to the outer wall. If the opening is deep enough, then you can add back a second skin of bricks to make the house warmer when the fires not in use.

I used about 5 bags of vermiculite with a 6" liner; it'll stop the liner banging about when the chimneys swept, and it'll insulate the liner making it draw better.

 

[vinn]

Closure Plate or Register Plate are simply different names for the same plate - they are not different kinds of plates.

Vermiculite is something of an old method - with modern appliances and liners there's no need for infilling with vermiculite around the SS liner - its a messy, uncertain business.
Often, the vermiculite was mixed with cement powder that would firm up the mix in the flue - a bad practice in my opinion.

 

[Doggit]

A register plate is used when there's no liner, and must be made of metal in case any bricks drop, and it can have an opening in it to allow the chimney to be swept if you can't go up through the burner. A closure plate is used when there's a liner, and can be made of cement board or metal.

Modern vermiculite has no cement in it, but yes, it can be messy to work with, and tricky in windy conditions, but it's a personal choice to use it or not It's often mixed with heat grade cement nowadays to use in pizza ovens as insulation.

 

[pilsbury]

Got a feeling the chimney is solid double brick like the rest of the house - looks like a Flemish bond.

 

[stuart45]

When building a new chimney with clay liners a cement/verm mix is used to stabalise the flue. Years ago mortar was used.
If you put cement in the mix with an S/S liner you would have a lot of trouble when you came to replace it.

 

[pilsbury]

Been bashing around today and now have a decent opening. The bricks that made the throat are properly solid even when the brick fireplace was removed so I intend to leave them in situ. Can't see them falling down of their own accord when my hammer doesn't budge them.

I think I'm just gonna use a liner with no filler.

Anyone got an idea what might clean the bricks up? Would be a lot easier than rendering as they seem in good nick apart from the soot.

I'll be laying quarry tiles on the concrete hearth and fire place I think.

 

[Doggit]

Don't wet the bricks whatever you do, as the soot will just soak further in. I've yet to find a method of cleaning sooted bricks up, so it'll be interesting to see what others have to say. Post a picture up the chimney though. You'll need to wire brush where you're going to set your closure plate so that you can seal around it.

Nice job so far.

 

[vinn]

Wire brushing is the only method - even a dry scrubbing brush wont be nearly as effective as a wire brush.
You could clean them up and render with a sand and lime mix or use backer board on three sides - it really all depends on what kind of finish you want. IMO old brick is best.

Your latest pic shows what appears to be (perhaps historic) smoke stains bleeding through the panel of wood above the mantel. Was there a mirror on that panel? Dont attempt aggressive removal of the staining, just leave alone.
The smoke came over the front of the brick arch it didn't penetrate the c/breast brickwork from the flue.