How often should a boiler be serviced?
Once a year, for gas, oil and heat pumps. Here is why, when in the year to book it, and what a missed service can cost you.
The short answer: once a year
Every boiler, gas, oil or LPG, should be serviced once a year. Heat pumps too. That is what manufacturers recommend, what most guarantees require, and what keeps a boiler safe and efficient.
If you want one rule to follow, book your boiler service around the same time every year, and keep the record from each visit.
Why every year and not every two?
Your guarantee usually depends on it
Most boiler manufacturers make an annual service by a registered engineer a condition of their guarantee. Skip a year and a later claim for a failed part can be refused, even if the fault has nothing to do with the missed service. Check your guarantee terms, but assume annual is required unless they say otherwise.
Safety
A gas boiler that is burning badly can produce carbon monoxide, which you cannot see or smell. The flue gas analysis on a service is how an engineer spots that. Oil boilers are not immune either: a blocked flue or poor combustion on an oil boiler can also produce carbon monoxide.
Fit a carbon monoxide alarm near any fuel-burning appliance, whatever the fuel.
Efficiency and running costs
Oil boilers in particular lose efficiency over a year. Soot builds up on the heat exchanger and acts as insulation, so more of the heat goes up the flue. The nozzle wears and the spray pattern degrades. A service resets both.
Gas boilers drift less, but their combustion still needs checking against the manufacturer’s figures.
Catching small faults early
A weeping valve, a failing expansion vessel or a condensate trap starting to block are cheap to deal with on a service visit. Left alone, they become a breakdown on the coldest night of the year.
Gas, oil and heat pumps: does the interval change?
| System | Recommended interval | Who services it |
|---|---|---|
| Gas boiler | Every 12 months | Gas Safe registered engineer |
| LPG boiler | Every 12 months | Gas Safe registered engineer |
| Oil boiler | Every 12 months | OFTEC registered technician |
| Air source heat pump | Every 12 months (check your guarantee) | Engineer trained on heat pumps |
Oil boilers working hard, for example in a large farmhouse or a home that runs the heating most of the day, can need attention more often if they start to smoke or lock out. Our technicians will tell you if they think yours does.
When is the best time to book?
Oil: late summer or early autumn
In Northern Ireland, most oil-heated homes turn the heating on properly in October. Servicing in August or September means:
- engineers have more availability before the rush;
- a fault is found before you need the heat;
- the boiler goes into winter clean and set up.
It is also a good time to check your oil tank before the first big winter fill.
Gas: any time, but not in a panic
Gas boilers run all year for hot water, so the timing matters less. The main thing is to keep to roughly the same month each year so you do not drift past 12 months and out of your guarantee terms.
If you have already missed it
Book now. A late service is far better than none, and it restarts your record. If the boiler is under guarantee and a year has been missed, check your guarantee terms or contact the manufacturer to see where you stand.
Landlords: service versus gas safety record
If you let a property in Northern Ireland with gas appliances, you must have a gas safety check carried out every year by a Gas Safe registered engineer and give the record to your tenants. This is often called a CP12 or landlord gas safety certificate.
A gas safety check and a boiler service are not the same thing. The safety check confirms appliances are safe to use; the service maintains the boiler to the manufacturer’s spec. Most landlords book both together. See our landlords page for the combined price, £119.
For oil-heated rentals, there is no oil equivalent of the CP12 in law, but an annual OFTEC service with a CD/11 record is the sensible standard and the evidence you want on file.
How to never miss a service again
The Blueprint Service Plan books your annual service for you: gas £72, oil £82 or heat pump £119 a year paid up front, compared with one-off prices of £79, £89 and £129. Repairs are always charged, with 15% off labour and 10% off parts for members. See boiler care plans.
If you prefer to pay as you go, book the next service when the engineer finishes this one, or set a reminder for the same month next year.
Can I service my own boiler?
Not a gas boiler: in Northern Ireland, as in the rest of the UK, gas work must be done by a Gas Safe registered engineer. For oil, there is no law stopping a homeowner, but a proper service needs a combustion analyser to set the burner, and guarantees generally need a recorded service by an OFTEC registered technician.
What you can do yourself is keep an eye on the boiler between services: check the pressure gauge on sealed systems, keep the area around the boiler and flue clear, and act on smells, smoke, soot or new noises. See boiler pressure low and boiler noises.
Book your annual service
Gas £79, oil £89, heat pump £129, fixed and including VAT. Book online or email [email protected].
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