What the job involves
A boiler repair starts with working out what has actually failed. The engineer will ask about the symptoms: no heating, no hot water, a boiler that locks out, pressure that keeps dropping, odd noises, or an error code on the display. They then inspect the boiler, run it through its cycle and test the parts they suspect. The diagnosis is the skilled part of the job, because several different faults can look the same from the outside.
Once the fault is found, the engineer either fixes it on the spot or tells you which part is needed. Common repairs include replacing a pump, diverter valve, pressure sensor, thermistor, ignition electrode, fan or circuit board. Others are clearing a blocked or frozen condensate pipe, topping up and re-pressurising a sealed system, or fixing a leak. Larger faults, such as a cracked heat exchanger, can push the conversation towards replacement.
Gas boilers must be worked on by a Gas Safe registered engineer. Ask to see their ID card, which shows which types of gas work they are qualified to do. Oil-fired boilers are normally looked after by engineers registered with the relevant oil heating scheme, and electric boilers have their own considerations. After the repair, a competent engineer will check the boiler is running safely and tell you if anything else needs attention.
What affects the price
Repair costs vary more than most people expect. These are the things that move the price up or down:
- Call-out and diagnosis charge. Some firms charge a set call-out fee and then labour on top. Others include the first stretch of work in one figure. Emergency, evening, weekend and bank holiday visits usually cost more than a planned weekday appointment.
- The fault itself. A quick fix such as a condensate clear or a re-pressurise needs little time and no parts. A failed circuit board or fan costs more in both parts and labour.
- The part. Prices differ widely between manufacturers and between genuine and pattern parts. Parts for common models are usually cheap and easy to get. Parts for older or less common boilers can be dear, slow to arrive, or no longer made.
- Boiler make, model and age. Some boilers are simple to get into and well supported. Others are cramped, awkward to strip down, or need manufacturer-specific tools or software.
- Access and location. A boiler in a loft, a tight cupboard or a high wall position takes longer to work on. Difficult parking or a long walk with equipment can add time.
- Whether the engineer carries the part. If the part is in the van, one visit may be enough. If it has to be ordered, you may pay for a second visit.
- Related work found on the day. A leaking valve, a failing pump or system sludge may turn up while the engineer is diagnosing the fault. That adds to the job, though it may save a repeat visit later.
- Type of system. Combi, system and regular boilers have different components. Unvented cylinders and older heating controls add more places for faults to hide.
- Warranty or cover. If your boiler is under manufacturer warranty, or you have a service plan or home emergency policy, some or all of the cost may be covered, subject to the terms.
- Your area. Labour rates and travel time differ between regions, and between cities and rural areas.
The prices on this page show what other homeowners actually paid, which gives a better guide than a general average.
Ways to keep the cost down
- Do the simple checks first. Look at the pressure gauge, check the thermostat and programmer settings, make sure the boiler has power and gas, and look at the display for a fault code. If the condensate pipe runs outside in cold weather, it may have frozen. Your manual will show what is safe for you to do. Do not remove the casing on a gas boiler.
- Note down the symptoms. When does it fail, what does it do, what does the code say? A clear description saves diagnosis time.
- Have the paperwork ready. The make, model, installation date, previous service records and any warranty details help the engineer and may change who pays.
- Check your cover. Look at any boiler warranty, service plan, home insurance extension or landlord responsibility before you book.
- Book at a sensible time. If you have a working alternative for a day or two, a standard weekday slot costs less than an emergency visit.
- Get more than one quote for larger repairs. For a simple fix this is rarely worth the wait. If you are quoted for an expensive part or a big repair, a second opinion is reasonable.
- Ask for the options. Where there is a choice, ask about genuine versus alternative parts and what each means for reliability and any warranty.
- Keep the boiler serviced. An annual service will not prevent every fault, but it can catch worn parts before they fail in the middle of winter.
- Do not delay. A small leak or a pressure problem left alone can turn into a bigger and more expensive repair.
What should be included in a quote
For anything beyond a basic visit, ask for the following in writing:
- The engineer's or company's name, address and Gas Safe registration number (for gas boilers)
- The fault found, in plain language
- The call-out and diagnosis charge, and whether it is deducted from the repair if you go ahead
- Labour, stated as a fixed amount or as an hourly rate with an estimated time
- Each part, with make and part description
- VAT, if the business charges it
- Whether the part is in stock or must be ordered, and the likely wait
- Any charge for a return visit
- Any warranty on the parts and the labour
- What happens if the repair does not solve the problem or a further fault appears
- Payment terms and how long the quote stays valid
Questions to ask a heating engineer
- Are you Gas Safe registered, and can I see your ID card?
- Is the diagnosis fee separate, or included in the repair price?
- Is the price fixed, or could it change once you open the boiler?
- Do you have the likely part with you, or will it need ordering?
- Is this part genuine or an alternative, and what warranty does it carry?
- Is the boiler worth repairing, or am I putting money into something near the end of its life?
- Did you find anything else that is likely to fail soon?
- Will you check the boiler is operating safely when you finish?
- Will you give me an invoice that lists the work and parts?
How long it takes and what to expect
Many repairs are done in a single visit. Diagnosis can take a while, particularly with intermittent faults, and the fix itself may be quick once the cause is clear. If a part has to be ordered, the job may be split across two visits, with the delay depending on the supplier and the boiler.
The engineer will need clear access to the boiler and may need to turn the gas, water or electricity off for a time. You may be without heating or hot water while they work. Clear the area around the boiler beforehand and make sure someone adult is at home. Once the work is done, ask them to show you the pressure, the controls and anything you should watch for. If your boiler keeps failing or the engineer finds a safety issue, they may advise against using it until it is put right.
Signs a quote is too cheap or too expensive
Possibly too cheap
- No Gas Safe number, or reluctance to show an ID card
- A price given over the phone with no idea of the fault or the model
- No mention of parts, or vague wording such as "all parts included" with nothing itemised
- No warranty on the work
- Pressure to pay in cash up front, or a very low figure that is later increased on site
Possibly too expensive
- A call-out charge far above what other firms offer locally, with no reason such as an emergency slot
- Labour that looks high for a straightforward fault
- Parts priced well above what the same part costs from suppliers
- A recommendation to replace the boiler without a clear explanation of what is wrong with it
- Unrelated extras added to the repair, such as a chemical flush, without a stated reason
Compare any quote with the prices on this page, and ask the engineer to explain any item that looks out of line. A good engineer will be glad to do so.