Interwar semis
With one bathroom, usually a combi in the kitchen. The cylinder and both loft tanks come out, and the airing cupboard is yours again.
Back boilers · Coulsdon CR5
Back boiler replacement in Coulsdon
Many of Coulsdon’s interwar semis are on their second or third boiler, but some still have the older arrangement: a back boiler behind the fire and tanks in the loft. If that’s your house, we’ll replace it with a modern boiler sized for how you live now.
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First things first
Is it a back boiler?
If you can’t find a boiler on a wall anywhere in the house, there’s a hot water cylinder in the airing cupboard, and the living room has a gas fire in the chimney breast, you very likely have a back boiler. Its controls are often behind a panel at the bottom of the fire.
Please don’t take the fire front off to look. A photo of the fireplace from the room, one of the airing cupboard and one of the loft tanks if you can reach them safely are all we need to tell you what you have and price the replacement.
For the job in general see back boiler replacement. For repairs and servicing in the area, see our Coulsdon page.
Coulsdon homes
What usually replaces a back boiler here
Bungalows
Everything is on one floor, so the new boiler often goes in the kitchen or a utility room, where it’s easy to reach for servicing.
Larger homes in Old Coulsdon
With more bathrooms, a system boiler and cylinder may suit better than a combi. We’ll recommend based on how many showers run at once.
The survey
What we check before we quote
A back boiler replacement changes more than the boiler, so we look at the whole system.
Mains pressure and flow
A combi gives only as much hot water as the mains brings in. We measure it so you know what the showers will be like.
Gas pipe size
A new boiler in a new room needs a gas supply sized for it. If the pipe from the meter is too small, it’s upgraded.
Flue route
The new boiler needs its own flue through a wall or the roof, positioned to meet the rules on windows, doors, boundaries and eaves.
Condensate drain
Modern boilers drain water through a small pipe. We find a route to a drain that won’t freeze in a cold snap.
Radiators and pipework
Going from open-vented to sealed raises the pressure in the pipes. We look for weak valves and old radiators before it goes live.
What good looks like
What you get with a new combi
If you choose a combi to replace your back boiler, this is what goes in.
- 1
The right boiler, properly sized
Chosen for your hot water demand and the home’s heat loss, with mains pressure and flow measured on the survey. Not just the biggest one on the van.
- 2
A new flue, in a legal position
Flue terminals must sit clear of windows, doors, boundaries and eaves. A new flue kit goes in with every boiler.
- 3
Magnetic system filter
Catches the rust and sludge that circulate in older systems before they reach the boiler’s heat exchanger.
- 4
Gas supply sized for the boiler
Combis can need more gas than the boiler they replace. The pipe from the meter is checked and upgraded if it’s too small.
- 5
Condensate drain that won’t freeze
Routed inside to a drain where possible. Outside runs are kept short, insulated and wide enough not to block in a frost.
- 6
Controls that meet Boiler Plus
Time and temperature control as a minimum, and on a combi an extra energy-saving measure such as a smart thermostat with optimisation.
- 7
System cleaned and protected
Radiators and pipes flushed, then dosed with inhibitor to slow new corrosion. Required by the regulations and by every manufacturer.
- 8
Commissioned and signed off
Gas pressure and combustion checked with an analyser, the Benchmark checklist completed, Building Control notified and the warranty registered.
Sizing guide
What size boiler do I need?
A rough guide for Croydon homes. Bigger isn't better: an oversized boiler cycles on and off and wastes gas. We confirm the size by checking your water pressure and flow rate on the day of the survey.
| Home | Bathrooms | Usually suits | Output |
|---|---|---|---|
| Flat or 1 to 2 bed house | 1 bathroom | Combi | Around 24 to 28kW |
| 3 bed house | 1 bathroom | Combi | Around 28 to 32kW |
| 3 to 4 bed house | 1 bathroom + en-suite | Larger combi | Around 32 to 38kW, if mains flow allows |
| 4 bed or more | 2+ bathrooms used at once | System boiler + cylinder | Sized to the home’s heat loss |
In Coulsdon
Back boiler replacement nearby
FAQ
Back boiler questions from Coulsdon
How long does a back boiler replacement take?
Usually 2 to 3 days. The back boiler, fire, cylinder and tanks come out, and the new boiler is fitted in a different room. Your quote will say how long for your home.
Can I keep my gas fire?
The gas fire in front of a back boiler is usually fitted to it, so it comes out with the boiler. You can have a new gas fire fitted afterwards. Mention it in the quote if you want one.
Can I still get a gas boiler to replace it?
Yes. There is no ban on replacing a gas boiler in an existing home. A modern condensing gas boiler is a normal replacement for a back boiler.
Do you cover Old Coulsdon and Chipstead Valley?
Yes, all of CR5, and Purley next door. See our Purley back boiler page.
Is parking a problem?
Rarely. Most Coulsdon streets have driveways or easy on-street parking, which helps on a job where a cylinder and tanks come out.
Guides
Read before you decide
- Choosing a boilerWhat is a back boiler?What a back boiler is, how to tell if you have one, why they were fitted in 1930s and post-war homes, and what replacing one with a modern boiler involves.Read the guide
- Choosing a boilerCombi vs system vs regular boiler: which is right for your home?Combi, system or regular boiler? How each one works, which homes each suits, and when changing type makes sense. A plain guide from Gas Safe engineers.Read the guide
- Choosing a boilerCan I still get a gas boiler?Can you still get a new gas boiler? Yes, for existing homes. What the rules are for new builds, what a replacement must meet, and how heat pumps compare.Read the guide
Everything we do
New boilers
Conversions
Repairs & servicing
Price your Coulsdon back boiler replacement
Photos of the fireplace and airing cupboard are enough to get started.