Opening a fireplace and fitting a stove

[stuart45]

//www.diynot.com/forums/building/removing-old-fire.394795/#3039993

Have a look at the pic in this thread.

You need to put in a concrete raft lintel to support the liners with an adaptor to take the stove pipe into the flue.

 

[Bilabong007]

Hi,

I found some similar pics http://www.uwe.port.ac.uk/heating/chimneys/section4.htm and can see it will definitely need some kind of support.

Googling raft lintel doesn't really help, is that a one piece thing or something built in situ?

Is there enough support in the liner to hold its own weight as you break out the existing lintel or should I be propping it up

Many thanks

Graeme

 

[stuart45]

You can buy the raft lintel pieces, or it can be cast insitu. It depends how the liner was built in as to whether it will support itself. If loose fill insulation was used it won't, but if a mortar mix was used the liners will usually be OK for a while.
What people often do is to put a long drill bit through near the bottom and leave it in till the work is done and then make good the holes.

 

[Bilabong007]

Ok thanks for that! will need to drill around the flue liner and see what's there. Fingers crossed it's not loose fill.

The drill bit idea is a stroke of genius

Will google raft lintels some more and see what it throws up

Thanks again

Graeme

 

[Bilabong007]

Well i cracked on today helping a friend open up the fireplace.

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• Bilabong007
• 6 Sep 2014
• 1

Turns out that it was brick and mortar infill behind the concrete flue. It is a lightweight concrete (not exactly pumice) that may not need lined. It seems pretty solidly held in so not sure if the infill needs additional support?

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• Bilabong007
• 6 Sep 2014
• 1

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• Bilabong007
• 6 Sep 2014
• 1

Next step is the hearth and figuring out exactly what to do with the liner/not liner situation. The guy who swept it certified it as a class 1 chimney and said dont bother. Every hetas guy i have spoken to would line so??

Any thoughts appreciated

Graeme

 

[Norcon]

I'd go with the sweep.

 

[Bilabong007]

Thanks norcon, what's your thoughts on support for the infill?

 

[Norcon]

Not sure what you mean.

 

[Bilabong007]

The infill round the concrete flue.

It's bricks and mortar shown in pics but not like a proper wall.

Think it's worth putting some support under it or just leaving as is?

 

[Norcon]

It's looks solid enough from the image.
I poured mine with solid concrete.

 

[stuart45]

If you are going through BC they may want a lintel to support the liners. Although the mortar round the liners will probably hold them in place, if there is any movement you could get damage to the joints.
HETAS often advise a metal liner as in general an appliance will work more efficiently with one in place. However they don't usually last as long as other liners.

 

[Bilabong007]

Hi Stuart,

I thought this may be something BC would bring up.

How would you support the concrete cylinders without obstructing or piercing them? Best I can think of is a steel sheet with a hole cut in it and mounted on angle brackets or similar

Bit like a register plate I guess

Graeme

 

[stuart45]

You might need to check with the BCO about the steel, as a register plate isn't really structural, but he may accept it. Other option is a concrete raft lintel.

 

[Bilabong007]

Looks like it will need to be a raft to make sure they have no quibbles when BC inspect it.

Correct me if I'm wrong, but the plan is:
Remove more of the infill to above lintel height
Remove 2 bricks from above the front lintel
Install some rods resting on top of the lintel and let into bricks at the back (spacing and size?)
Shutter the bottom allowing for the flue to poke through
Pour concrete

I can do the first bits then get hazy on size and spacing of rods. Also how to make the shutter solid enough to hold the weight and not let the concrete flood out. I have never mixed concrete before.

Going to need to read lots to get this done or a serious point in right direction.

Graeme

 

[stuart45]

You need to get the flue to sit on top of the raft lintel, rather than the flue pipe sticking through it. The hole needs to allow for the fitting of a stove pipe adapter.