DIYRemoval of Cast Iron Chimney Flue & Fitted Fireplace From a BISF House.
By Non Standard House Member Doug.
(Admin note: Non Standard 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 house. 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 work overall with hood as 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 disconnected by a Corgi registered engineer.
- Any electrical connections should be removed by a qualified electrician.
- 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 re-commisioning 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.
Flue Removal Process
Additional Steps at bottom of post.
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)
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)
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)
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)
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)
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 wooden 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)
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
Admin Update - Additional Flue removal process images
Fantastic post Doug, thank you for sharing this with everyone.
I have been dying to get my old flue and fireplace removed but hadn't a clue how to do it and hubby kept saying it's too difficult! Lol You've just proved him wrong hahaha
It does look pretty easy for the average diy'er did you face any problems or obstacles?
No real problems as such I found cutting and removing the tube quite simple and took about half a day. The frame surrounding it is a little tricky as some of the nuts and bolts on one side joining the frame together are difficult to access due to the stud wall placed up against it, I had taken pictures of this but sadly I had a corrupted memory card so unable to retrieve them.
Have uploaded a couple more the first one is in the bedroom with tube removed but with the clamp and frame in stiu
The second is the tube in stiu you can clearly see the wooden batons that sit in the angle frames which are nailed in place through a hole in the steel these need to be removed to access the frame bolts,The right hand one is tricky to remove as the plaster board is nailed to it
But a competent DIY’er should have no trouble. If you require any further information let me know
Fascinating post Doug even though I have no plans to remove mine, which is in use by the boiler. I am looking into whether it's possible to remove the ugly mismatched pink tile fireplace and gas fire that have been stuck onto the front of the firebox.
As you say that the flue is in use I’m Guessing you have a back boiler fitted Baxi? if this is the case the gas fire is part of the boiler and you have a very limited and expensive choice of fire fronts, If still available. As for the tiled surround you can do what you like providing you keep the existing dimensions e.g. Depth /size of opening. But don’t forget that you would need to consult a Gas Safe engineer before you start any work when a open flue gas boiler / fire are concerned due to ventilation requirements. if you could post a picture should be able to give you some advice.
Hi Doug, we do indeed have a Baxi back boiler for the hot water and central heating, model Bermuda SL3. I was thinking of replacing it either with a combi boiler elsewhere (problem is nowhere obvious to put it) or a modern Baxi Bermuda condensing back boiler in the same place. However, after using relatively little gas last winter I shelved that idea as I thought it would take a long time to recoup the money through increased boiler efficiency.
I was hoping to be able to remove the gas fire unit and fireplace and replace them with a more stylish fire surround/non operational fireplace and leave the back boiler as it is. I suspect though that the fire and boiler might have to be together to work.
The fireplace is large and takes up quite a bit of room but I can live with that, but the way the gas fire has been stuck on the front sticking out even further into the room looks ugly I think.
You are correct in thinking that the fire and boiler are connected and you can’t remove the fire to replace with another type. Baxi used to do a selection of different forefronts but were hugely expensive. Even if you went down the new back boiler route the flue liner will need to be replaced at a cost and they only have an electric fire on front although there is talk of a gas one in the pipeline. Most boilers fitted into BISF houses are installed into the old cylinder cupboard and flue through the roof, I’ve fitted them into kitchens and also in the old side shed
Here are some photos, you can see how far into the room the gas fire sticks out. I wanted to take it out and everything in front of the bricks you can see where I've taken the side panel off, so that the mantelpiece is the front-most part of it to give a more normal look.
To clarify, I wanted to know if the boiler would work without any type of fire in front of it, as they appear to operate independently or are the two things actually one unit?
They do operate independently of each other but are classed as 1 unit and should not be separated occasionally we disconnect the back boiler and decommission it leaving the appliance in place with the fire usable but there are regulations covering this. So you will be unable to reduce the amount it sticks out but might be able to shave some off the sides.
However you could remove the surrounding tiles and mantle to replace with different tiles or any non-combustible material providing the finish surface is the same thickness as existing so the fire sits against it
In fact I have seen it done with a pre made mantle surround and marble effect infill from B & Qs. The gas fire casing is easily removed to expose the surround
Thanks Doug for your advice, it's a pity but kind of what I was expecting.
The engineer who checked it when we bought the house said we should keep it as he said they are very reliable and inexpensive to maintain. Hopefully having insulated the loft and started to insulate the walls our gas bills will be further reduced this winter!