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Removal of Cast Iron Chimney Flue & Fitted Fireplace From inside a BISF House.

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Doug
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Removal of Cast Iron Flue Pipe & Fireplace From a BISF House by Member Doug.

(Admin note: BISF House member Doug has kindly put together the following excellent post showing the complete process of a cast iron flue removal inside a typical BISF hous.e. In creating this post and taking the time to record the entire process, Doug hopes that he can share his experience with other members and more importantly he hopes that it may be a useful resource for others. Our sincere thanks to Doug for this valuable contribution)

Hello everyone here at BISF House.

I recently removed the cast iron flue and fireplace from a BISF house and thought that I would share it with you all. This post relates to BISF Houses where the fireplace is fitted to wall between the living & dining rooms.

Before starting there are few safety points to bear in mind.

  • You will need a 6-12 inch cast chain cutter. This is a heavy item and will require 2 persons to complete the job.
  • Always wear safety glasses and gloves and if possible, steel toecap shoes just in case.
  • Always wear a high quality dust mask and wherever possible always dampen down any insulation material that may surround the flue with a spray bottle of water. Although not prescribed, we can never rule out the possibility that installers may have used asbestos insulation in some cases. If you suspect the presence of asbestos do not undertake this work until the material has been correctly tested by an approved body.
  • Always wear a disposable worksuit with hood. This can be an extremely dusty job.
  • Never use an angle grinder as sparks can easily ignite insulation or travel under floorboards, causing fire.
  • A strong working platform and extra lighting in the roof would also be a good idea.
  • Don't remove any of the supporting frames yet as it contains the pipe clamps which keeps the flue pipe in place. You can work around the frame without any problem.E
  • Ensure that any and all pipework leading into or out of the fireplace are disconnected or safely capped off away from the work area.
  • All gas pipes should be diconnected by a Gorgi registered plumber.
  • Water pipes if present should also be removed and capped if of no further use.
  • Always turn the gas off at the mains prior to undertaking any work as there may be hidden gas pipes that you are not aware of.

Originally, BISF houses were fitted with open coal fires that heated a small sealed back boiler that was situated behind the main firebox. This was a basic water or oil filled unit that heated radiators in the house. If still present, the box and pipework should be capped and carefully removed.

Admin Update: There have been a number of safety incidents including one fatality where old solid fuel back boilers have exploded due to the recommisioning of old coal fires. Such events are not specific to BISF Houses. Please see http://www.hse.gov.uk/services/localgovernment/boilers.htm

In the 1980's many BISF properties were fitted with Baxi Bermuda gas fires with integrated backboiler. The back boiler was positioned inside the firebox, directly behind the fire itself.
This fire is fairly straightforward to remove once the gas feed has been safely disconnected. The front of the gas fire can pulled forward and carefully separated from the independant back boiler. You may find several mounting screws that need to be removed and possibly a pipe connection but the two parts of the fire and boiler should seperate.

First, completely remove the existing fireplace surround. The surround is usually constructed from large slabs which should be pretty easy to break up using a lump hammer or similar. It would be wise to dismantle the top mantle slab first. One stripped away you should be left with the concrete firebox surround. (Images 1 & 2) and also the boxing from around flue in the front bedroom.  ( Images 3 & 4) Note the flared joint located 2 thirds up in the bedroom. (Image 5)

Firstly remove the fire place surround

Side view of fireplace

First, remove the fire place surround (Images 1 & 2) and also the boxing from around flue in the front bedroom.  ( Images 3 & 4) Note the flared joint located 2 thirds up in the bedroom. (Image 5)

 Starting in the attic the below image shows the cast iron flue tube passing through the ceiling plate as it starts its journey down through the house via the first floor ceiling (Image 6)

The next image shows the flue at the point where it exits the roof toward the chimney. You can see at this point that it is clamped into place by a surrounding bracket. (Image 7)

Loft Support

As I won't be disturbing the top part of the flue, my first cut will be just under this top clamp, The chain cutter is feed around the tube and locked into position then slid up to the first cut. (Image 8)

Pipe Cutter

 The cutter works on a ratchet system which slowly tightens the chain until it cracks the tube, it's quite noisy and a bit scary. Also a note as there was a gas back boiler and fire a liner has been fed through the tube as this needs to be removed first I made 2 cuts. (Image 9)

Cut Pipe

Then using a reciprocating saw through the small gap I cut through the liner then removed the small flue section before removing the liner by pulling down and out from the lounge fireplace. I found this the dirtiest job so be warned lots of soot rust etc. came down with the liner. (Images 10 & 11)

A manageable flue section was cut lower down near the ceiling plate. (Images 12 & 13)

*CAUTION* if you cut off a flue section which is unsupported the top cut section jumps upwards due to the force of the cut, BE PREPARED.

My next cut was in the bedroom tight to the ceiling pic 1 then half way above floor level Pic 2 then at floor level pic 3. You could cut larger sections but I opted to keep small sections. (Images 14, 15 &16)

One more cut in the lounge third of the way from the ceiling the cut section being removed from above. The last section which sits in a plate on top of the fire box you can wriggle until its lose and tilt back to lift out. (Image 17)

Flue Frame

You are now left with the frame which is bolted together in 4 sections then another 4 sections in the bedroom bolted to the downstairs frame. (Images 18 & 19)

There are wood batons nailed in the corner angles to which the plasterboard was nailed too, you can pull the nails out to remove the baton to enable to access the frame bolts. This is straight forward but a fiddly job. The bottom of the frame is cast into the concrete plinth I cut the frame at floor level to enable me to remove it as won't be taking up the concrete plinth just yet. Once all the frame has been removed the concrete fire box can be removed in sections although a little heavy easily removed. (Image 20)

Studwork

Then making good the ceilings and floors is the last job but as I'm about to undertake a major refurbishment of the lounge the making good will be part of that project. (Image 21)

My local scrap merchant took all the scrap away at no cost to me he even loaded it himself!

Hope this is helpful any questions just ask
Doug

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Topic starter Posted : 1:09 am
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Hi Ed, glad to hear that your flue removal is going well. I'm surprised to hear that you're getting good results with an angle grinder as I tried this once using a standard steel cutting blade, but the blades wore down so quickly. I have since found a much better multi purpose steel rather than carbon type blade that lasts longer and cuts almost anything. What type of blade have you been using and what size angle grinder?
Are you going to remove the chimney casing too or are you going to block it off?

It's a hefty old pipe too and as you say, cutting and removing it in sections is vital to prevent injury and having removed a few I was surprised to see that the cast iron itself was still in excellent condition, despite having read several reports stating that the pipe would probably have started to corrode by now. What condition was your flue in?

I look forward to seeing any photos that you might have taken too Ed, please keep us updated.

Marc

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Posted : 11:38 am
Ed (Senior Member)
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Hi Marc, it's all out now together with the frame, fireplace and firebox so the only things left are the concrete slab that the firebox sat on (that I'll have to break up before making good the floor) and the last bit of flue that goes through the roof (this and the chimney box thing round it will go when the roof covering is eventually replaced).

I hadn't actually used an angle grinder before so I'm not sure what to compare it with, but the flue cut more easily than I was expecting. I used a Norton flat metal cutting disk 115 x 2.5 x 22.2 mm ( http://www.toolstation.com/shop/p21095?table=no) and a 110V 'pro' grade angle grinder that I borrowed from my dad, so perhaps it cut better than a DIY angle grinder. He advised to use the 2.5 or 3mm disks rather than the thinner ones which can shatter.

The steel frame around the flue was actually much tougher to cut and wore out the disks much more quickly than the flue itself even though there was a lot less to cut through. I had to cut it off at the base where it is cast into the concrete slab and also in a few other places where either the nuts had rusted or it wasn't possible to get a spanner in to loosen them.

The outside of the flue was in fine condition but there was a fair bit of rust on the inside. I'd say about a cup full or two of rust fell out of each roughly 600mm flue section when I dumped it outside.

When I dismantled the fireplace I found a scrap of the Bristol Evening Post that looked as though it had been used to fill a gap, that contained a report of a meeting of the Imperial Tobacco Company on 21 March 1950 so I guess that can be used to date the house. It's a bit later than I was expecting as the woman who sold the house said her father had lived here for 62 years till his death in mid 2011.

I also found a capped off lead pipe behind the fireplace which looks like a gas pipe, so perhaps the original heating system was gas rather than coal?

I'll post some photos later, I also have some of the bathroom now it's finished.

Ed

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Posted : 4:53 pm
Ed (Senior Member)
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Bedroom before. You can see the radiator needed moving as it's in the way of the door. I'm planning to replace it with one of those plinth heaters.

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Posted : 8:45 pm
Ed (Senior Member)
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Most of the steel frame round the flue removed. As you can see I had to cut one of the cross pieces with the angle grinder as I couldn't get to the bolt from the cupboard side. I've taken the flue out down to the collar and cut the first cut below the collar. I hadn't taken account of the fact that the collar section is much heavier so you should really cut this out in a shorter piece!

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Posted : 8:52 pm
Ed (Senior Member)
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More cut out, you can see the flue liner as well. It's a bit unusual because it has rockwool type insulation round it and then a plastic sleeve so it was too snug to pull out in one go like Doug did.

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Posted : 8:56 pm
Ed (Senior Member)
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Flue cut off as close to the floor as possible and you can see how I've lifted the cut sections off the liner.

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Posted : 8:59 pm
Ed (Senior Member)
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Flue liner cut off and the clamp that holds the flue in place visible.

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Posted : 9:02 pm
Ed (Senior Member)
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Fireplace taken out. Does anyone know what the hole to the left was for? It's open to the outside as I can feel the air come through it. Was it some sort of drain or for ventilation?

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Posted : 9:11 pm
Ed (Senior Member)
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Flue completely out and dismantling the steel lining of the hole through the floor. This bit was quite fiddly.

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Posted : 9:12 pm
Ed (Senior Member)
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Just the steel frame left to take out downstairs

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Posted : 9:15 pm
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