How Long Does a Boiler Service Take? And Every Other Job, Timed
Key points
- An annual boiler service takes about an hour. Access and the age of the boiler move it either side of that.
- A repair is anywhere from twenty minutes to two visits. Diagnosis is quick. Whether the part is in the van is what decides the day.
- A power flush is most of a day, because every radiator is done in turn.
- A new boiler swapped for the same type in the same spot is one day. A conversion, a back boiler removal or moving the boiler takes longer, and we say so before we book it.
- Nobody can give you an exact figure before they see it. What we can do is tell you honestly which of these you are in.
A standard annual boiler service takes about an hour. Everything else depends on what is wrong, and the honest answer for a repair is somewhere between twenty minutes and a second visit. This page sets out what each job actually involves, so you know what you are booking out your day for.
How long does each job take?
| Job | Typical time | What makes it longer |
|---|---|---|
| Annual boiler service | About an hour | Awkward access, a boiler we have not seen before, or a fault found on the day |
| Landlord gas safety check | About an hour for one appliance | Every extra appliance, a cooker or a fire, adds to it |
| Service and safety check together | Around an hour and a half | Number of appliances |
| Repair, part on the van | Twenty minutes to two hours | How buried the part is. Some sit behind half the boiler |
| Repair, part has to be ordered | Two visits | Part availability, and older boilers are worse |
| Power flush | Most of a day | Number of radiators, and how badly blocked they are |
| New boiler, same type, same place | One day | Flue route changes, gas pipe upgrades |
| Conversion, back boiler, or boiler moving room | Longer than a day | We tell you how long when we give you the price |
What takes the hour in a boiler service?
Most of it is checks rather than spanner work, which is why a service that is done in fifteen minutes should worry you.
The engineer takes the case off, inspects the burner, the heat exchanger, the seals and the electrodes, and cleans what needs cleaning. Then comes the part that actually proves the boiler is safe: the flue gases are measured with a calibrated analyser, and the gas pressure and gas rate are checked against what the manufacturer says they should be. The condensate trap is checked, the safety devices are tested, the system pressure is set, and the readings are written down on a service record you keep.
That is the hour. There is no way to do the measuring part quickly, and the measuring part is the whole point. The full list is in what is included in a boiler service, and what a boiler service costs covers the price.
Need to know before you book the morning off? Tell us the boiler and what it is doing, or call 0191 540 2051, and we will tell you how long we expect to be. Book online.
Why can a repair be twenty minutes or two visits?
Because finding the fault and fixing it are two different jobs, and only one of them is predictable.
Diagnosis is usually quick. An engineer who works on these every day will often know from the fault code, the noise and the pressure gauge what has gone before the case is off. Our error code guide covers the common ones.
What decides the rest of the day is the part. A fan, a pump, a diverter valve, a pressure sensor and the common Worcester, Vaillant, Baxi and Ideal spares are carried, so those are usually done on the spot. Something unusual, or anything for a boiler that has been out of production a while, has to be ordered, and that makes it two visits. We will tell you which one you are in while we are stood there, not afterwards.
The other thing that stretches a repair is how buried the part is. Two components that cost about the same can be half an hour apart in labour, purely because of where the manufacturer put them.
Why is a power flush a whole day?
Because it is not one flush, it is one per radiator. The machine is connected to the system, cleaning chemical goes in, and then each radiator is isolated and worked on in turn so the sludge actually lifts rather than being pushed somewhere else. A badly blocked radiator sometimes has to come off and be flushed outside.
At the end the system is refilled, dosed with inhibitor and the radiators are balanced. A house with fifteen radiators takes longer than a house with six. More on what it is for in black water when you bleed a radiator, and the price is on the power flushing page.
Why is a new boiler a full day?
A like for like combi swap is one day, and the day is fuller than people expect. Floors get protected, the system is drained, the old boiler comes off, the new one goes on with its flue and pipework, the system is cleaned and refilled, the boiler is commissioned and gas tested, and then you get shown the controls and handed the paperwork.
Expect to be without heating and hot water for most of that day. Everything is running and tested before we leave. There is an hour by hour account in what happens on the day your new boiler is fitted.
What makes it longer than a day is changing what the system is, rather than changing the boiler. Coming off a cylinder and loft tanks onto a combi, taking out a back boiler, or moving the boiler to a different room are all bigger jobs, and we tell you that at the quote rather than on the morning.
Book it in and we will tell you how long we need
Services from £80 plus VAT. No call out charge on repairs. Gas Safe registered, covering Sunderland, Durham, Houghton le Spring, Washington and the wider North East.
Book online Call 0191 540 2051What if the service finds something?
You get told before anything else happens, with what it costs to put right, and you decide. A service is an inspection, so a fault found on the day is quoted separately rather than quietly added. If it is something small and we have the part, we will often sort it there and then, which adds to the hour. If the boiler is unsafe it gets turned off and labelled, which is a requirement rather than a choice.
Common questions
Do I need to be in the whole time? Someone needs to let us in and be there at the end. You do not need to stand and watch.
Will my heating be off? Briefly during a service, for most of the day on a new boiler, and on and off during a power flush.
Can you do a service and a safety certificate in one visit? Yes, and that is the sensible way to do it. Allow around an hour and a half for one boiler. See landlord gas safety certificates.
Why do some firms quote thirty minutes for a service? Because they are not doing all of it. Ask whether flue gas analysis is included and ask for the printed readings afterwards.
Can you give me a time slot? We give you a window and ring ahead. Heating work runs over sometimes, and we would rather tell you than leave you waiting in.
Where to go next
Book a boiler service, or go to your local page for Sunderland, Houghton le Spring, Durham or Washington.
If the boiler has already stopped, go to boiler repairs instead. If you are weighing up replacing it, see new boiler installation.
About the author
Alex Robson is a Gas Safe registered heating engineer and the owner of AR Heating & Gas, based in Houghton le Spring and working across Sunderland, Durham, Washington and the wider North East. Last updated 12 October 2026.