Boiler Repair

Why is my boiler losing pressure?

A boiler that needs topping up more than a couple of times a year has a leak — either from the heating circuit (pipework, radiator valves, towel rails), from the boiler's internal expansion vessel losing its charge, or from a pressure relief valve that's passing water out through the overflow pipe.

The pattern tells us a lot before we arrive. Pressure that drops slowly over weeks usually means a weep at a radiator valve or a joint under the floor. A sudden drop to zero points at the pressure relief valve lifting — confirmed by a wet or stained discharge pipe outside. Pressure that falls only when the heating runs, or rises too high and then dumps, is the classic signature of a flat expansion vessel — a repair measured in an hour, not a day.

What we won't do is shrug and tell you to keep topping up: constant fresh water brings fresh oxygen and hardness minerals into the system, and in Surrey's 300+ ppm water that means accelerating scale and corrosion. Finding the leak is always cheaper than feeding it.

Boiler fault codes: what do they actually mean?

A fault code is the boiler's own diagnosis of which check failed — ignition, flame detection, pressure, overheating, fan or sensor faults — but it names the symptom, not always the cause. An ignition lockout code might mean a failed electrode, a gas supply issue or a blocked condensate pipe backing up into the burner.

Each manufacturer uses its own dialect of codes, and low-pressure and ignition-lockout ones dominate the winter call sheet, and some have a safe DIY first step — repressurising via the filling loop to around 1.0–1.5 bar, or pressing reset once after a power cut. If a code returns after one reset, stop resetting: repeated resets on an ignition fault can mask a flue or combustion problem that needs a Gas Safe engineer, not persistence.

This is where diagnosis earns its fee. We carry the manufacturers' fault trees and the test gear to follow them — multimeter, manometer, flue gas analyser — so the part we fit is the part that failed. The expensive version of boiler repair is three visits of guesswork parts; the cheap version is one visit of measurement.

Should I repair or replace my boiler?

Repair when the boiler is under roughly 10 years old, the fault is a standard component, and the repair costs a small fraction of replacement. Replace when a boiler past 12–15 years needs a major part — heat exchanger, main PCB — or when repair bills are becoming an annual event.

The arithmetic we walk you through is plain. A £150 fan on an eight-year-old boiler is an easy yes. A £600 heat exchanger on a fourteen-year-old boiler is money placed on an appliance where the next failure is already queuing, parts are getting scarcer, and efficiency has drifted well below a modern condensing unit's 92%+ ErP. Because we both repair and install, the recommendation carries no hidden incentive: the repair and the new boiler quote come from the same engineer on the same visit if you want them.

What does a boiler repair cost?

Most boiler repairs cost between £120 and £400 all-in: a fixed diagnosis fee from £85 that includes the first hour, then a quoted price for parts and fitting before any work goes ahead. Common single-visit repairs — ignition electrodes, pressure sensors, diverter valves — typically land between £150 and £300.

The larger numbers attach to the big components: expansion vessels and fans sit in the £200–£350 territory, pumps similar, printed circuit boards £300–£450 depending on the boiler, and heat exchangers £500 upwards — which is where the repair-or-replace conversation starts. Every price is agreed before we fit anything; there is no "while we were in there" line on our invoices. And the no-fix-no-fee promise means what it says: if we cannot diagnose the fault, the diagnosis fee is not charged.

What should I do if my condensate pipe freezes?

A frozen condensate pipe is the most common cold-snap breakdown and often a DIY fix: the boiler locks out with a gurgling noise and an ignition fault code, and thawing the frozen section of the external white plastic pipe — warm (not boiling) water poured along it, or a hot water bottle held against it — usually restores the boiler after a reset.

The pipe in question carries condensate out to a drain, and where it runs outside — common on the 1930s semis in Molesey and Walton where the boiler sits on an outside wall — a hard frost can freeze it, the condensate backs up, and the boiler shuts itself down for safety. The frozen section is usually at the open end or an elbow.

The permanent fix is better than the annual ritual: we re-run external condensate pipes in 32mm or 40mm pipe at a proper fall, insulate them with waterproof lagging, or re-route them internally where possible. It is an inexpensive job in October — easily combined with an annual boiler service — and a miserable discovery at 6am in January — book it before winter, not during it.