Gas safety check vs boiler service: what is the difference?

Landlords and lettings agents often ask whether they need a gas safety certificate, a boiler service or both. They are different jobs with different purposes, though they overlap and are usually done together.

The short version

	Gas safety check	Boiler service
Purpose	Confirm appliances are safe to use now	Keep the boiler working well and catch wear
Who needs it	Landlords, by law, every 12 months	Anyone with a boiler, usually yearly for warranty
Covers	Every gas appliance and flue the landlord provides	The boiler, and with a cylinder, its controls
Case off and cleaning	Not required	Yes
Output	Landlord gas safety record (CP12)	Service record and Benchmark entry

What the gas safety check is

The landlord gas safety check is a legal duty under the Gas Safety (Installation and Use) Regulations 1998. A Gas Safe registered engineer checks each gas appliance and flue the landlord provides for:

• Gas tightness, meaning no leaks
• Correct burner pressure or heat input
• Safe removal of fumes through the flue
• Enough air supply where the appliance needs it
• Safety devices working

The result is a gas safety record. Tenants must get a copy within 28 days, and new tenants before moving in. The HSE landlord FAQ sets out the rules.

What a service is

A boiler service follows the maker’s service instructions. The engineer removes the case, inspects and cleans the burner, heat exchanger and condensate trap, checks seals, electrodes and the fan, checks the flue, runs a combustion test with a flue gas analyser, and checks pressure, the expansion vessel and controls. Our post on what a boiler service includes goes through each step.

Why one does not replace the other

HSE is clear. It says you should not assume that an annual service inspection includes the points required by a safety check. A service note for the boiler does not cover the gas hob or gas fire, and it may not be written in the form a gas safety record needs.

The other way round, a safety check confirms the boiler is safe on the day but does not clean or adjust it. A boiler can pass a safety check while its condensate trap is half blocked or its expansion vessel is flat. Those are the things that cause breakdowns mid tenancy.

Why landlords usually book both

The maintenance duty

As well as the yearly check, landlords are responsible for maintaining the appliances, flues and pipework they provide. HSE says there is no set timeframe, but good practice is to show regular, annual maintenance. A yearly service is the simplest way to show it.

The warranty

Most boiler makers make a yearly service a condition of their guarantee. Worcester Bosch says yearly servicing must be completed each year. Vaillant says the boiler must be serviced annually. A gas safety check alone does not meet those terms.

Fewer callouts

A breakdown in a let property means an unhappy tenant, an urgent repair and sometimes a duty to provide temporary heating. A yearly service reduces that risk.

One visit

Booking both at the same time means one access arrangement with the tenant, one engineer visit and one date to remember. In Clapham and similar areas, where most lets are flats with tenants who work long hours, one visit is much easier than two. Our Clapham area page covers the flat conversions there.

Hard water and a let combi

In London, combis in let flats work hard. Thames Water says all the water in its region is hard. Over time scale builds up in the combi’s hot water heat exchanger. A safety check will not usually pick this up. A service with a hot water flow check will. Catching it early saves a cold shower complaint later. See our combi boiler service page.

Homeowners

If you live in your own home, you do not need a landlord gas safety record. A yearly service is what makers ask for and what keeps the boiler safe. Some homeowners ask for a gas safety check on other appliances too, such as a gas fire, which is sensible if it has not been checked for a while.

When the dates do not match

If your gas safety record and your boiler service fall at different times of year, you can line them up. The gas safety check can be done up to two months early and keep the original expiry date. Our post on renewing a gas safety certificate early explains how. A service done a few weeks early is generally fine for warranties, but check your maker’s terms.

Booking both

On our landlord service and CP12 page you can book the safety check alone or add a full service. Tell us how many gas appliances are in the property and give tenant contact details.

Gas work in the UK must be done by a Gas Safe registered engineer. Check the engineer’s ID card, including the back, which lists the appliance types they are qualified for, and the number on the Gas Safe Register.