Faults, in plain English

Boiler repairin Milton Keynes

What the common faults usually mean, what to have to hand before you ring, and when a repair is still the right call. Safety first, though: read the next section before anything else.

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Read this first

When it is not a repair job, it is an emergency

Two situations where you stop reading, put the phone down on us and ring the emergency line instead.

You can smell gas

Ring the National Gas Emergency Service on 0800 111 999. Free, answered around the clock. While you wait, open the doors and windows, put out anything burning, leave the light switches and other electrics alone, and turn the gas off at the meter if you can get to it safely. Do not wait for a heating engineer and do not ring us first.

You suspect carbon monoxide

There is nothing to smell or see, which is the whole problem. What you can look for is a flame burning lazy yellow or orange instead of crisp blue, and sooty or yellow brown marks around the appliance. Headaches, sickness, dizziness or muddled thinking that lift when you go outside are worth acting on. Switch the appliance off, shut the gas off at the meter, open the doors and windows, get everyone into fresh air, ring 0800 111 999 and see a doctor. Fit an audible alarm if you have not already, and test it.

Anyone who works on the gas side of your boiler has to be on the Gas Safe Register. Ask for the ID card on the doorstep, every time, including with an installer we pass you to.

Symptoms

Common faults and what they usually point at

General patterns, not a diagnosis of your boiler. Only an engineer standing in front of it can tell you what is actually wrong.

Pressure dropping

A sealed system that keeps falling below the pressure marked on the gauge is losing water. Common places are a radiator valve, a weeping joint under a floor, or the expansion vessel having lost its charge, which shows up as pressure swinging high when hot and low when cold.

No hot water, heating fine

Points at whatever handles hot water specifically: a diverter component on a combi, or on a stored system a motorised valve, a cylinder thermostat or the wiring centre they all run through.

Locking out on ignition

The boiler tried to light, could not prove a flame and shut itself down. Behind it might be ignition electrodes, a flame sensing fault, a gas supply problem or a blocked condensate pipe that has backed up, which is why this one turns up in cold snaps.

Water where it should not be

Anything dripping from the boiler or pooling underneath needs the boiler switched off at the service switch and an engineer called. Water and mains electricity in one box is not something to watch and see.

Banging, kettling or gurgling

Kettling, that boiling kettle rumble, usually means scale or sludge restricting the heat exchanger. Gurgling is often air in the system. Neither is instantly dangerous. Both are the system telling you it wants attention before something expensive gives up.

A fault code on the display

Modern boilers show a code rather than just stopping. It narrows the search but it is not the answer on its own, because the same code can be thrown by several different failures. Write it down exactly as shown and quote it when you ring.

The judgement call

When repairing is right, and when it stops being

Nobody should be pushed into a new boiler because a part failed once.

Repair is normally the sensible answer where the appliance is reasonably young, the fault is one component, that component is still manufactured, and the boiler has otherwise behaved itself. Fixing it and getting several more winters out of it is a perfectly good outcome.

It stops being sensible when the same boiler needs an engineer every winter, when the part has been discontinued, or when the appliance is old enough that the next fault lands on a component nobody can supply. At that point you are paying for delay rather than for heat. If that sounds like yours, work through boiler replacement, which sets out the signs properly, and new boiler cost for what a replacement involves financially.

The other thing worth saying: most repairs happen to boilers that have not been serviced. An annual visit does not make a boiler immortal, but it catches the small things and it keeps the manufacturer warranty alive. See boiler servicing.

Before you ring

Have these four things to hand

It sounds fussy. It is the difference between an engineer arriving with the right part and arriving to have a look.

Make and model. Usually printed on a label on the boiler case, often behind the flap on the front or underneath.
The fault code, exactly as it appears on the display, letters and numbers both.
Roughly how old it is. The Benchmark checklist or the paperwork from the original installation will tell you if you still have it.
What it is actually doing, and when it started. Intermittent or constant, hot water only or heating too, worse when it is cold outside.

A photograph of the boiler with the front open, and another of the pressure gauge, saves a lot of conversation.

How it works here

What happens when you send a repair request

Worth being straight about this, because repair is not the same as a quote for a new boiler.

We are a referral service. We do not attend, diagnose or fix anything. Choose Repair on the form and your details go to an installer in our network who also takes repair work, and they contact you directly to arrange a visit and to tell you what it will cost.

Installers differ in how much repair work they take on. Many concentrate on installations and fit repairs around them, so response times vary, and they vary most in the middle of a cold snap when every heating engineer in Milton Keynes is already booked. If your boiler has failed completely and the house is cold, say so in the message so it is treated as urgent.

If nobody in the network can get to you quickly enough, say so and ask us to pass it on again, or find a Gas Safe registered engineer directly through the Gas Safe Register. An unheated house in January is not the moment for loyalty to a website.

Repair questions

Boiler faults, answered straight

Plain answers to what people in Milton Keynes ask before they replace a boiler.

My boiler keeps losing pressure. Can I just keep topping it up?

Topping it up once after bleeding the radiators is normal. Doing it every week is not. A system that will not hold pressure is losing water somewhere, and that water is going either onto a floor, into a ceiling or out through the pressure relief pipe outside. Repeated topping up also adds fresh oxygenated water every time, which is exactly what rots a system from the inside. Get it looked at rather than living with it.

The heating works but there is no hot water. What does that usually mean?

On a combi it often points at the part that switches the boiler between heating and hot water, or at a heat exchanger that has scaled or blocked. On a system or regular setup it is more likely to be the cylinder side: a motorised valve that is not moving, a failed cylinder thermostat, or a wiring centre fault. Either way it is a diagnosis job, not something to guess at from a web page.

What is a lockout, and is it safe to keep resetting it?

A lockout is the boiler shutting itself down because it tried to light and could not prove a safe flame. One reset after a power cut or a brief gas interruption is reasonable. Resetting it over and over is not, because you are repeatedly asking an appliance to do the one thing it has already decided it cannot do safely. If it locks out twice, leave it off and get an engineer to it.

Is it worth repairing a boiler that is already fifteen years old?

Sometimes, if the part is cheap, available and the rest of the appliance is sound. Often not. Spares get harder to find as ranges are discontinued, and the next fault could be the one nobody can source a part for. Ask the engineer two questions: is this part still made, and what else on this boiler is near the end of its life.

Do I need a Gas Safe registered engineer for a repair, or will any plumber do?

Anyone you pay to work on a gas appliance in your home must be on the Gas Safe Register, and they should carry an ID card showing what they are qualified to work on. Ask to see it and check it. Plumbing is not the same qualification as gas work, and a general plumber who is not registered must not touch the gas side of the boiler.

Cold house? Start here

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