Replacing a boiler is one of those expenses nobody looks forward to, but understanding the costs upfront takes the sting out. This guide breaks down exactly what a new boiler costs in 2025, from the cheapest combi swap to a full system conversion with all the extras.
New Boiler Costs by Type (2025)
| Boiler Type | Boiler Only | Installation | Total (Installed) |
|---|---|---|---|
| Combi (like-for-like swap) | £700 – £1,800 | £800 – £1,500 | £1,800 – £3,500 |
| Combi (new location/conversion) | £700 – £1,800 | £1,200 – £2,500 | £2,200 – £4,500 |
| System boiler + cylinder | £1,000 – £2,200 | £1,000 – £2,000 | £2,500 – £4,500 |
| Regular (conventional) boiler | £800 – £1,500 | £800 – £1,500 | £1,800 – £3,000 |
Cost by Brand
| Brand | Tier | Combi Price (Boiler Only) | Warranty |
|---|---|---|---|
| Alpha / Glow-worm | Budget | £600 – £900 | 5–7 years |
| Baxi / Ideal | Mid-range | £800 – £1,200 | 7–10 years |
| Worcester Bosch / Vaillant | Premium | £1,100 – £1,800 | 10–12 years |
| Viessmann | Premium | £1,200 – £2,000 | 10–12 years |
Hidden Costs to Watch For
| Extra Cost | Price Range | When It Applies |
|---|---|---|
| Magnetic filter (system cleanse) | £100 – £250 | Recommended for all installs |
| Chemical power flush | £300 – £600 | Old systems with sludge buildup |
| Flue extension | £50 – £150 | Boiler far from external wall |
| Gas pipe upgrade | £150 – £400 | Older properties with narrow pipes |
| Condensate pipe run | £100 – £250 | Routing to a drain/soakaway |
| Wireless thermostat | £100 – £300 | Upgrading from basic timer |
| Scaffolding (if needed for flue) | £200 – £500 | High-level flue access |
| Asbestos removal (old flue) | £200 – £800 | Pre-1985 properties |
Regional Price Differences
| Region | Avg. Combi Install (Like-for-Like) |
|---|---|
| London & South East | £2,500 – £3,800 |
| South West | £2,200 – £3,200 |
| Midlands | £2,000 – £3,000 |
| North England | £1,800 – £2,800 |
| Scotland | £1,900 – £2,900 |
| Wales | £1,800 – £2,800 |
How to Get the Best Deal
- Always get 3+ quotes – we’ve seen £1,500+ differences for identical work
- Ask about 0% finance – many installers offer 24–60 month interest-free plans
- Check for grants – ECO4 may fund a boiler if you’re on qualifying benefits
- Avoid emergency replacements – if your boiler is 10+ years old, start getting quotes before it breaks
- Don’t buy from door-knockers – they typically charge 30–50% more than local Gas Safe engineers
- Check Gas Safe registration – verify your installer at gassaferegister.co.uk
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Is It Worth Repairing Instead?
Repair If:
- Boiler is under 8 years old
- Repair cost is under £500
- It’s a one-off fault (not recurring)
- Parts are readily available
Replace If:
- Boiler is 12+ years old
- Repair cost exceeds £500
- It’s broken down 3+ times in 2 years
- Parts are obsolete or hard to source
- It’s a non-condensing model (pre-2005)
Frequently Asked Questions
How long does a boiler installation take?
A straightforward like-for-like combi swap takes 1 day. Conversions (e.g., regular to combi) or relocations typically take 2 days. Complex jobs with pipework changes, power flushes, or cylinder installation may take 2–3 days.
Can I get a free boiler on ECO4?
Possibly. If you’re receiving qualifying benefits (Universal Credit, Pension Credit, etc.) and your current boiler is inefficient or broken, your energy supplier may fund a replacement through the ECO4 scheme. Contact them directly to check eligibility.
Should I buy the boiler myself or let the installer supply it?
Let the installer supply it. If you buy a boiler separately, most manufacturers won’t honour the full warranty, and the installer may not guarantee work on equipment they didn’t supply. The “saving” of buying online rarely outweighs the warranty risk.
Learn More About Boilers
Our complete boiler guide covers types, brands, and everything you need to know before buying.