Should I Repair or Replace My Boiler? The Honest Maths

When a boiler breaks down, the question isn't just "can it be fixed?" — it's "is it worth fixing?" Here's how we think it through with customers, honestly. Sometimes the answer is a repair, and we'll say so.

Repair usually makes sense when…

• The boiler is under about 10 years old and has been serviced.
• It's a one-off fault — a pump, a fan, a diverter valve, a pressure issue.
• Parts are readily available for that model.
• The repair cost is a small fraction of a new boiler.

Before you call anyone, check the simple stuff: is the pressure right (see boiler losing pressure), is the condensate pipe frozen (see frozen condensate pipe), and is the gas and electricity on? Our guide to no heating or hot water runs through the checks.

Replacement usually makes sense when…

• The boiler is 15+ years old, especially an older non-condensing model.
• It's breaking down repeatedly — two or three callouts a winter adds up fast.
• Parts are obsolete or hard to find, so every repair takes longer and costs more.
• The repair quote is a big chunk of the cost of a new boiler.
• Your heating bills are high and the boiler is inefficient. An older non-condensing boiler can run at 70–80% efficiency, against 90%+ for a modern condensing model.

The rough numbers

2026 guides put a like-for-like combi replacement at roughly £2,500–£4,000 supplied and fitted, with a system-to-combi conversion at around £4,000. A typical repair is a few hundred pounds. So one repair on an otherwise healthy boiler is usually the right call; a third big repair on a 17-year-old boiler usually isn't. See our new boiler cost guide for more.

Stop using it now if…

• There are black or sooty marks around the boiler.
• The flame is lazy, yellow or orange instead of crisp blue (on boilers with a visible flame).
• Your carbon monoxide alarm goes off, or people in the house have headaches, dizziness or nausea that ease when they go outside.
• You can smell gas.

If you smell gas or suspect carbon monoxide, turn off the appliance, open windows, get everyone outside and call the National Gas Emergency number on 0800 111 999. Then have it inspected by a Gas Safe registered engineer.

What we do

We repair and replace boilers across Preston and the surrounding areas. We're Gas Safe registered (203011) and a Baxi Approved Installer, so we can offer extended warranties on select new Baxi boilers. If a repair makes more sense, we'll tell you. Call 07949 075721 or use the form below.