Short answer: A gas safety check tests whether each gas appliance and flue is safe to use on the day. A boiler service is maintenance: the engineer inspects, cleans and adjusts the boiler to the manufacturer's instructions so it keeps working safely and efficiently. Landlords need the safety check by law. HSE recommends servicing too, usually every year.
The two get mixed up all the time. Landlords ask for a boiler service and expect a certificate. Homeowners book a safety check and expect the boiler to be cleaned. Around 70 people a month in London search for “boiler service and gas safety certificate” together, according to Keyword Planner. This guide sets out what each one is, so you book the right thing.
The short version
| Gas safety check | Boiler service | |
|---|---|---|
| Purpose | Confirms appliances and flues are safe on the day | Keeps the boiler working safely and efficiently |
| Covers | Every gas appliance and flue in scope: boiler, hob, gas fire | The boiler only, unless others are added |
| Legal for landlords | Yes, every 12 months under regulation 36 | Recommended by HSE, not a separate legal record |
| Legal for homeowners | Not required | Not required |
| Paperwork | Landlord gas safety record, if a let property | Service report or record in the boiler manual |
| Warranty | Usually not enough | Usually needed by the manufacturer |
| Cleaning and adjusting | No, testing only | Yes, to the manufacturer’s instructions |
What a gas safety check covers
A safety check confirms four things on each appliance: the flue removes fumes properly, the appliance gets enough air to burn, the gas pressure or heat input is right, and it operates safely. These are the regulation 26(9) checks that HSE says a landlord record must confirm (HSE). The engineer runs the appliance, measures and records.
It is a snapshot. It does not take the boiler apart, clean the burner or replace worn seals.
For more detail, see what a landlord gas safety check includes.
What a boiler service covers
A service follows the boiler manufacturer’s instructions for that model. It usually includes:
- removing the case and inspecting the inside of the boiler
- checking and, where needed, cleaning the burner and heat exchanger
- cleaning the condensate trap on condensing boilers
- checking seals and gaskets
- checking system pressure and the expansion vessel
- testing safety devices
- running a combustion test with a flue gas analyser
- checking the flue and terminal
HSE says gas appliances and flues should be serviced in line with the manufacturer’s instructions, and if these are not available, annually unless the engineer advises otherwise (HSE).
Why landlords in Walthamstow often book both
Waltham Forest has a lot of rented homes. At the 2021 Census, 27.8% of households rented privately (ONS), and the council’s selective licensing scheme runs until 30 April 2030 (Waltham Forest Council).
Many lets are in Warner Estate half houses, where one terraced house is two flats, each with its own front door (Lloyd Park Conservation Area appraisal). That often means two boilers and two sets of appliances in one building. Booking the safety check and service together means one visit per flat, one appointment for tenants to be in, and one set of paperwork to file.
The hard water matters too. Thames Water’s 2025 reports put the Highams Park zone at an average of 276 mg/l and Leyton at 270 mg/l (Thames Water, Highams Park; Leyton). That is “hard” on Thames Water’s scale. A safety check will not spot slow scale build up inside a combi. A service has a better chance. See hard water and your boiler.
Read more about the area on our Walthamstow page.
What homeowners should book
Homeowners have no legal duty to do either. Gas Safe Register recommends an annual gas safety check (Gas Safe Register), and most boiler warranties ask for an annual service. A common approach is:
- an annual boiler service, to keep the warranty and the boiler in good order
- a safety check of the hob and any gas fire at the same visit
What neither of them covers
Two things fall outside both:
Pipework. HSE notes the annual safety check does not cover installation pipework as such. It recommends asking the engineer to test the whole system for soundness and look over visible pipework (HSE, pipework).
The heating system water. Neither a check nor a standard service cleans the radiators and pipes. Sludge and scale in the system water need a separate clean. Our post on power flushing before a new boiler explains the options.
When a check finds a fault
If a safety check finds a problem, the engineer follows the industry unsafe situations procedure. An appliance that is At Risk is turned off with your permission and labelled. That is not a service and not a repair. The fault then needs fixing, which may mean the parts and cleaning that a service would have covered. Booking the service at the same time often means the engineer can deal with small issues, such as a blocked condensate trap or a dirty burner, in the same visit. Larger faults are priced separately once the engineer has looked. See what it means when a gas engineer turns off your boiler.
Booking
When you contact any engineer, say clearly which you need: “landlord gas safety record”, “boiler service”, or both. Give the list of appliances. London Gas Engineers books both across north and east London. Ask any engineer for their Gas Safe ID card and check the back lists the appliances they will be working on.
Quick questions
Can a gas safety check and a boiler service be done at the same visit?
Yes. Many landlords book both together. The engineer does the safety checks on every appliance and the full service on the boiler, then issues the record and the service report.
Does a boiler service give me a landlord gas safety certificate?
Not on its own. The landlord record must list every gas appliance and flue you provide, with the specific checks HSE sets out. Ask for both if you need both.
Does a gas safety check keep my boiler warranty valid?
Usually not. Manufacturers generally ask for an annual service to their instructions. Check your warranty terms, as they vary by brand.
Last updated 23 October 2026. Written for homes in London. Rules can change, so check the linked sources for the latest position.