How to remove a back boiler
5 mins
How to remove a back boiler
What is a back boiler?
When excavating a fireplace you may be removing a back boiler.
A back boiler is some kind of metal (copper or steel) vessel that holds water and is embedded within a fireplace.
When “live” it is connected by two copper pipes to a cylinder upstairs. These pipes will often run up the side of a chimney breast (may be boxed-in under wallpaper) but they may be embedded within a wall. The back boiler may also be connected to a heat sink radiator.
To understand how a back boiler (sometimeshidden inside a wood burning boiler stove) works see: connecting wood stoves to radiators.
Image: Back boiler (about the size of a shoebox). Can fetch good money at the recyclers if made of copper.
In my experience 90% of all back boilers looks the same (see picture): a metal box, about the size of a shoebox connected to 22mm or 28mm copper pipes. However, a back boiler can be any shape (e.g. a matrix or fancy design).
If a back boiler is present then it must be removed and disconnected from the plumbing system (or investigated to ensure it already has been).
In general this is a job for a plumber.
VERY IMPORTANT NOTE
NEVER DISCONNECT A BACK BOILER AND THEN SEAL OFF THE TWO PIPES EXITING THE BACK BOILER AND THEN LIGHT A FIRE.
IN FACT ALWAYS REMOVE A DISCONNECTED BACK BOILER.
Why? Because water (even a tiny amount) will boil and the steam will cause a huge build up of pressure (water expands 1,600 times when converted to steam) and if that pressure cannot escape then the back boiler explodes.
Image: Large back boiler that made up the general shape of the old open fire
Is it live?
Back boiler live or not?
- If you can see a back boiler then there may be evidence that it is not live (“live” meaning full of water under some kind of pressure).
- If there is a hole in the back boiler then there can be no water in it (if a plumber disconnects a back boiler he may drill a hole in it to make it safe).
- If the pipes coming from the back boiler are cut then it is disconnected.
- If a cylinder has been removed then the back boiler almost certainly been disconnected (unless some strange plumber has linked it to a radiator or the general pipework).
Note: A back boiler might be disconnected from a cylinder or circuit but still hold quite a lot of water (trapped in the pipework from upstairs).
How do I remove a back boiler?
I drill a small hole in the boiler (e.g. 5mm) and see if any water spurts out. If it does I use a couple of buckets to collect the water (passing full ones to my assistant to pour away). Or I use a wet vac. Usually there will be no water or just a small amount (half a bucket from the pipes being common). The 5mm hole ensures that should a mistake have been made and the system be live at least there is a chance of stopping the flow (finger over hole).
My assistant did once put his SDS chisel through a back boiler pipe (he thought he was nowhere near it and was proceeding with opening up a builder’s opening whilst I investigated the plumbing). Luckily the house was being renovated (no carpets and a concrete floor) and so the resulting jet of water did no damage. We used large Gorilla buckets to collect the water although it progressively got hotter and hotter as the cylinder emptied itself from our pipe (and the gorilla buckets became rather soft and useless). Should this ever happen then all you can do is switch off the mains water and wait for the system to empty (this can be as much as a full cylinder AND a full loft header tank).
You might need
View allFAQs
See all FAQsCosts correct as of April 2023:
Approx. costs if you have a chimney and fireplace ready to use: £750-£1,000 (save £500 by self-installing).
Approx. costs if you have a chimney but need the fireplace "opening up": £1,600-£2,200 (save £1200 by self-installing).
Approx. costs if you do not have a chimney and need a clip-together flue: Shed £475-£700. Bungalow £1500. 2-storey house £2500. Save £1,000-£1400 by self-installing.
Above figures include labour and materials but no appliance.
We, of course, advise you to purchase your stove and materials from Stovefitter's to ensure quality goods are installed (some installers use budget materials to increase margin). If you buy your stove from us (rather than your local small shop or installer) we have a lot more power when approaching manufacturer's with a warranty issue. Why is that? Because we buy many hundreds of stoves a year from these brands.
We do not fit stoves.
But we know a few who do!
Google: Hetas installers
Hetas are the trade body of registered UK installers.
Most installations will require that you slide a chimney liner down your chimney (flexible metal tube 5" or 6" in diameter). Do you have a narrow chimney and want to lessen the risk that a liner might not go down your chimney? Then make sure your chosen stove can use a 5" liner.
Must I line my chimney? Best read this article but most likely the answer is yes. Do I have to fit a chimney liner?
DEFRA-Exempt wood burning stoves with a 5″ collar can usually be fitted to a five inch liner rather than the usual 6″ minimum, making the installer's job much less stressful.
ALL OF THE 5KW STOVES WE SELL CAN BE FITTED TO A 5" CHIMNEY LINER.
I seriously suggest any self installer fits a 5" liner unless they know their chimney is large enough for a 6"!
What is the best chimney liner? Silvacore 904 (we sell it so of course we will say that ;-). What is the best chimney liner?
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Will your stove require an air vent within the room (some stone walls are very difficult to drill)?
5kW or under and wood burning stoves often do not require an air vent (new builds always require an air vent).
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What is the maximum output in kW of your "5kW" wood burning stove? The majority of manufacturers just specify the “nominal output” and this figure means very little in real life. The nominal is a figure the manufacturer chooses to sell the stove at - the stove is capable of reaching at least this output with one fuel load. Nominal means "capable of". But it is not the maximum.
Check out the size of the area where the logs will go (firebox size) as this varies enormously. The kW output is completely dependant on the amount of logs burning at any one time - more logs burning equals more heat. If you can fit three logs in stove A and just two logs in stove B then stove A will be capable of throwing out 33% more heat.
DO NOT TRUST MANUFACTURERS’ kW RATINGS as manufacturers specify what output they desire to sell the stove at and testing allows for much “playing with the figures”. This is why you can get very small 5kW stoves (e.g. Aga Little Wenlock) and very large 5kW stoves (e.g. DG Ivar 5 by Dik Geurts which is actually rated 5kW but has a MUCH larger firebox than the Ekol Crystal 5 by Ekol Stoves). A Crystal 5k might get to 5kW and not be capable of any higher whilst a DG Ivar, despite being rated at 5kW, can get to 8kW with a full fuel load.
Note that, over time, one might damage the internal firebricks of a stove by running at a higher load than the manufacturer's suggest. Firebricks are easily replaceable.
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Will your wood burning stove fit in your recess WITH the required air gaps around it? This is obviously not an issue if your stove will be freestanding.
Air gaps to non-combustible materials (brick, stone etc.) are usually "as close as you like" legally but manufacturers will sometimes specify a recommendation. This recommendation is there to allow heat to escape from the recess into the room - so you get the heat benefit rather than the heat soaking into the building structure and being lost. If no gap to non-combustibles recommended then we suggest 50-100mm air gap left and right of stove, 50mm behind and 100mm above.
Are you in a Smoke Control Area (usually built up areas)?
Choose your stove accordingly.
A stove must be DEFRA-Approved if you wish to burn wood in a smoke control area.
ALL OF THE STOVES WE SELL ARE DEFRA APPROVED FOR SMOKE CONTROL AREAS.
In simple terms if a stove has an efficiency rating of 70% then 30% of the heat from your logs goes up the chimney.
If a stove has an efficiency rating of 90% then only 10% goes up the chimney.
So think of this in terms of how many logs you have to chop/buy.
Example: A Saltfire Peanut 5 by Saltfire Stoves in Dorset has an efficiciency of 80%.
A tall chimney (6m or more) that is lined will be happy with an efficient stove.
Efficiency importance can be said to be overrated and anything between 75% and 85% is fine. Go much higher and performance can actually suffer (smoke in room when opening door to reload, blackening of glass).
Many modern stoves can go on 12mm thick hearths. Others require full, 5″ thick constructional hearths. All of the stoves we sell state whether or not a 12mm hearth is suitable.More about hearths for wood stoves here.
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Can you can talk to somebody on the phone should you need to after the wood burning stove has been delivered, especially if you are self installing? Will the staff at “wesellzillionsofstoves.com” be able to assist with any installation issues? What if there are any problems after install?
Do yourself a favour before ordering stoves or materials on the Internet: Go to Trustpilot and type in the company name before you buy. Some companies advertising at the top of search engines are not good news - check for yourself.
When striving to find thebest 5kW wood burning stovesyou will likely be bewildered by the choice. There are many to choose from. The question I get asked most in our shop is “why should I pay <£1,000> for this one when this other one is just <£500>?”. Here is the very simple answer:the cheaper wood stoves are made in Chinaor Eastern Europe whilst the more expensive are made in Western Europe (or sometimes the USA). Here are a few examples where a more expensive stove might excel over a cheaper stove:
- Aesthetics (more time spent on design)
- Hinges (sometimes hidden on more expensive stoves)
- Better quality glass
- Thicker steel (longer life)
- Improved door locking mechanisms
- Longer warranty
- Improved controllabilty of flame due to more resource invested on design of air flow within stove
- Brushed steel fittings instead of cheapy chrome look
Open and close the door on a cheap Chinese stove. Then open and close the door on a DG stove, Arada stoves, Woodford stoves, Hamlet stoves or Saltfire stoves. You’ll understand the difference.
Stove pricing reminds me of wine pricing. A £20 bottle of wine is not double the quality of a £10 bottle of wine (the drinking experience might be improved by 20% as an example). We are talking “the law of diminishing returns here. They are all “fire in a metal box” at the end of the day.
Yes. However, there are specific regulations and restrictions in place to address air pollution concerns, particularly in areas designated as Smoke Control Areas. In these areas, only approved "smokeless" fuels or exempt appliances, such as Defra-approved wood-burning stoves, can be used. These stoves are designed to burn wood more efficiently and produce fewer emissions.
All the stoves we sell are DEFRA approved and Eco-design approved and suitable for all areas of the UK.
Terminology
View all TerminologyA stainless steel tube, slides down a brick/stone chimney to provide a smooth and safe route for smoke.
All of our stoves are approved by DEFRA to burn wood in all UK locations including Smoke Control Areas (towns and cities). Not all stoves are, so be careful if buying elsewhere.
All of our stoves are ECODESIGN approved to be sold in the UK. Not all stoves are, so be careful if buying elsewhere. ECODESIGN is mandatory by law since January 2022.
The base your stove sits on.
If the chimney is the polo mint then the flue is the hole.
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