02 / 06 Boilers & gas safety
Boiler Replacement
If your boiler keeps breaking down, is getting expensive to run, or an engineer has warned you that parts are hard to find, it may be time to replace it. Our boiler replacement service swaps your old boiler for a new one of the same type, usually in the same place, and brings everything around it up to today's rules. It is carried out by Gas Safe registered engineers, as the law requires.
Boiler replacement is part of our plumbing services. If you want to change the type of system, for example from a regular boiler with tanks to a combi, or move the boiler to another room, see our boiler installation service.
- Part ofPlumbing Services
- Our process5 clear steps
- Answered here6 common questions
- FreeSurvey & itemised quote
01When to replace
When Should I Replace My Boiler?
Age on its own is not a reason to replace a boiler that is safe, reliable and efficient. What matters is how it is performing.
Signs You Need a New Boiler
- Repeated breakdowns: The same or new faults every winter, with repair bills adding up.
- Parts are hard to get: Manufacturers stop making parts for older models, so repairs take longer or are not possible.
- Rising gas bills: An old non-condensing boiler uses noticeably more gas than a modern condensing one for the same heat.
- A failed heat exchanger: The most expensive part, often costing a large share of a new boiler.
- Noise and sludge: Kettling and slow-to-heat radiators can point to a system that needs cleaning, and a boiler that has been struggling.
- A safety warning: An engineer has classed the boiler as unsafe, or found signs such as soot staining or a yellow flame on an older open-flued boiler.
- An old back boiler: Behind a gas fire, which many people replace at the same time as the fire. A move to a new position is covered by our boiler installation service.
If you are not sure, a boiler repair visit will tell you what has failed and whether a repair is worth it.
02Old boilers
Is It Worth Replacing an Old Boiler?
If it is non-condensing, usually yes. Since 2005, almost every new gas boiler fitted in England has had to be a condensing boiler, which recovers heat from the flue gases that older boilers send straight outside. A quick check: a condensing boiler has a plastic condensate pipe running to a drain. Every new gas boiler must also now have an ErP efficiency of at least 92%.
| Repair usually makes sense when | Old boiler replacement usually makes sense when |
|---|---|
| The fault is a routine part (pump, fan, valve, sensor) | The heat exchanger or several major parts have failed |
| Parts are readily available | Parts are obsolete or on long order |
| It is a condensing boiler in good condition | It is non-condensing and your bills are high |
| Breakdowns are rare | Breakdowns are frequent and getting more so |
03What is involved
What a Like-for-Like Boiler Replacement Involves
A like for like boiler replacement means the same type of boiler, normally in the same position, but it is not just unbolting one box and fitting another. The new boiler must meet today's rules, so we also check:
- The flue: A new boiler is fitted with the flue system made for it. If the old flue position no longer meets the clearance rules, the position may need to change.
- Condensate: Replacing a non-condensing boiler means adding a condensate pipe to a suitable drain.
- The gas pipe: A new boiler may need more gas than the old one, so the supply pipe is checked and, where needed, upsized through our gas plumbing service.
- Controls: A new gas boiler needs time and temperature controls, and a combi needs one extra energy-saving measure. Our boiler installation page explains these Boiler Plus rules, and our thermostat and heating control installation service covers the options.
- A carbon monoxide alarm: In England, the building regulations require one in the room when a new boiler is installed.
- Paperwork: The installation is notified to building control through the Gas Safe Register, the Benchmark checklist is completed, and the boiler is registered with the manufacturer.
04Cleaning
Cleaning and Protecting the System
A new boiler connected to dirty water will not stay efficient for long. Old systems collect sludge (magnetite) and debris, which block the narrow passages in a modern heat exchanger. Before handover, the system is cleaned and a magnetic filter is fitted on the return pipe to catch debris, with inhibitor added to slow corrosion, following the British Standard for water treatment, BS 7593.
For heavily sludged systems, with cold spots at the bottom of radiators or black water when they are bled, a power flushing service is usually recommended first. Older, fragile systems may suit a gentler chemical clean instead.
05Heat pumps
Replacing a Boiler With a Heat Pump
If you are thinking of moving away from gas, the government's Boiler Upgrade Scheme gives a grant towards replacing a fossil fuel boiler with a heat pump in England and Wales. A heat pump works at lower temperatures, so it often needs larger radiators, a hot water cylinder and good insulation. This is a whole-system change, covered by our central heating system installation service.
06Cost
How Much Does It Cost to Replace a Boiler?
Boiler replacement cost is priced after a survey or photos, and you receive a written, itemised quote, fixed for a defined like-for-like job. The main factors are:
Every factor is priced line by line after your free survey — no guesswork, staged payments.
Get a free quote- 01
The new boiler's make, model and output.
- 02
The flue
A straight flue through an outside wall is simpler than a vertical or extended flue.
- 03
The gas pipe, if it needs upsizing.
- 04
Controls needed to meet the rules.
- 05
The system clean
A chemical clean or a power flush, plus the filter.
- 06
A condensate route, if the old boiler was non-condensing.
Timescale · 07
Can a Boiler Be Replaced in One Day?
A straight like-for-like swap is the quickest kind of boiler job, because the gas, water and flue connections stay in roughly the same place. Whether yours can be done in one day depends on the flue, the gas pipe, the condensate route and how much cleaning the system needs. We confirm the timing, and when you will be without heating and hot water, when we quote.
08Process
How It Works
Planned before we start, managed by one project manager, signed off at the end.
- 01
Survey or photos
The boiler, its data badge, the flue outside and the gas meter.
- 02
Written quote
The recommended boiler, controls and system clean, itemised.
- 03
Replace
The system is drained, the old boiler removed and the new one fitted.
- 04
Clean and commission
The system is cleaned and treated, and the boiler is tested and commissioned.
- 05
Hand over
We show you the controls and complete the paperwork. Most manufacturer warranties then need a yearly boiler service.
09Areas
Boiler Replacement Across London
We carry out boiler replacement across London, with a focus on east and south-east London. Find out more on our pages for boiler replacement in London, boiler replacement in Ilford, boiler replacement in Barking, boiler replacement in Dagenham, boiler replacement in East Ham and boiler replacement in Orpington.
10FAQs
Boiler Replacement FAQs
When should I replace my boiler?
When it breaks down repeatedly, parts are hard to get, a major part such as the heat exchanger fails, or it is an inefficient non-condensing boiler. Age alone is not a reason if it is safe and reliable.
How much does it cost to replace a boiler?
It depends on the boiler, the flue, the gas pipe, controls and how much the system needs cleaning. We give you a written, itemised quote after a survey or photos.
Is it worth replacing a 15-year-old boiler?
If it is non-condensing or keeps breaking down, usually yes. If it is a reliable condensing boiler with parts still available, servicing and repairing it can still make sense.
Can a boiler be replaced in one day?
A straight like-for-like swap is the quickest boiler job, but it depends on the flue, gas pipe and system clean. We confirm the timing when we quote.
Do I need to replace my radiators with a new boiler?
Not usually. Sound radiators can stay, but the system should be cleaned first so sludge does not damage the new boiler.
Can I replace my boiler with a combi?
Yes, but that is a change of system, not a like-for-like swap, because the tanks and cylinder are removed. It is covered by our boiler installation service.
11Plumbing Services
Explore other boiler services
Next step
Get a Free Boiler Replacement Quote
Send photos of your boiler, its data badge and the flue outside, and we will send you a written quote or arrange a survey.
Send us photos on WhatsApp to get started, or use our contact form.
- Free survey
- Itemised written quote
- One project manager