LPG Boiler Service: What Is Different From a Mains Gas Service?

An LPG boiler should be serviced once a year, the same as a boiler on mains gas, by a Gas Safe registered engineer who is qualified for LPG. That last part is where most booking mistakes happen. Gas Safe registration covers both natural gas and LPG, but each engineer is only registered for the types of gas and appliance they have been assessed on, and plenty of engineers who work on mains gas boilers every day are not registered for LPG. The service itself follows the same pattern as a mains gas service, with a few checks that matter more because of how LPG behaves and how it reaches the boiler.

Who Can Service an LPG Boiler?

Only a Gas Safe registered engineer whose registration includes LPG can legally service an LPG boiler. Being Gas Safe registered for natural gas is not enough on its own.

Every registered engineer carries an ID card, and the back of the card lists the work they are qualified to do. Look for LPG on that list, and for the right kind of property: LPG in a house or flat is a different category from LPG in a caravan, a residential park home or a boat. You can also check an engineer's qualifications on the Gas Safe Register website. Our guide on how to check an engineer is Gas Safe registered shows where to look on the card.

If your boiler runs on heating oil rather than LPG, you need a different trade altogether. Our article on how an oil boiler service differs explains who does that work.

How to Tell Whether Your Boiler Runs on LPG

If there is no gas meter connected to the mains and you have a gas tank or a set of gas bottles outside, your boiler almost certainly runs on LPG. In London that is uncommon, because nearly every street is on the gas network, but LPG turns up in some properties on the edges of Greater London, in outbuildings and annexes, and in homes that were never connected to the main.

The boiler's data badge, usually inside the front panel or underneath the casing, states the gas type. Many boiler models are made for natural gas and converted to LPG with a kit at installation, in which case there should also be a conversion label on the boiler. Your previous service record or the installation paperwork will say too. Tell whoever you book the fuel type at the start, together with the make and model.

What an LPG Boiler Service Covers

The core of the service is the same as on a mains gas boiler: the engineer checks that the boiler burns gas safely and efficiently, gets rid of its waste gases properly and shuts down safely if something goes wrong. A proper service normally includes:

• A gas tightness test on the installation pipework, to confirm there are no leaks.
• Checks on the burner, heat exchanger and condensate trap, cleaning where the manufacturer's instructions call for it.
• A combustion analysis with a flue gas analyser, read against the manufacturer's figures for LPG, which are not the same as the figures for natural gas.
• Gas pressure and rate checks. LPG is supplied to appliances at a higher pressure than mains gas, typically around 37 mbar for propane against about 20 mbar for natural gas, so the engineer confirms the boiler is getting the pressure it was set up for.
• Flue, seals and safety devices, including the flame supervision and any pressure relief and overheat protection.
• The conversion label and data badge, to confirm the boiler is set up for the gas it is actually burning.

At the end you should get a written service record. Most manufacturers need an unbroken yearly service history to keep a warranty valid, and that applies to LPG boilers as much as mains gas ones.

Why LPG Needs Extra Care Around the Installation

LPG is heavier than air, so escaped gas sinks and collects at low level instead of dispersing. That one fact explains most of the extra attention an LPG installation gets.

Leaked LPG can gather in cellars, basements, drains and low voids, where a spark can ignite it. For that reason the rules on siting LPG appliances below ground level are much stricter than for natural gas, and ventilation at low level matters more. An engineer servicing an LPG boiler should look at where the boiler and pipework are, not just at the boiler itself, and should raise anything that no longer meets the rules. This is particularly worth checking if the property has been extended or altered since the boiler was fitted.

If you ever smell gas, whether mains gas or LPG, turn off the supply at the tank, cylinder or emergency control if it is safe to do so, open doors and windows, do not use electrical switches, and call the National Gas Emergency number on 0800 111 999 or your LPG supplier's emergency line. Do not try to find or repair a leak yourself.

Who Looks After the Tank or Cylinders?

The boiler service covers the boiler and the pipework in the property. The bulk tank or the cylinders, and the regulator next to them, are often the responsibility of the LPG supplier, particularly where the tank is rented from them.

Check your supply agreement to see what the supplier maintains and how often they inspect it. On a cylinder supply, the engineer will usually look at the regulator, the hoses and the changeover valve as part of checking the installation, and will tell you if a hose or regulator is due for replacement. If the tank or anything on the supplier's side looks damaged or corroded, report it to the supplier rather than waiting for the next service.

Landlords With LPG: The Gas Safety Check Still Applies

If you let a property heated by LPG, you need an annual gas safety check and a Landlord Gas Safety Record (CP12), exactly as you would on mains gas. The Gas Safety (Installation and Use) Regulations cover LPG appliances too.

The check must cover every gas appliance and flue you provide, which on an LPG property can include a gas hob or cooker running from the same supply as the boiler. The engineer who does it needs the LPG qualification for the check to be valid. Our page on the Landlord Gas Safety Certificate explains what the inspection covers and how the record must be given to tenants. As with mains gas, the safety check does not replace the annual service the manufacturer asks for, so many landlords book both on one visit.

Booking an LPG Boiler Service

When you book, give the fuel type first, then the make, model and approximate age of the boiler, whether the supply comes from a tank or cylinders, and whether any other LPG appliances need checking. Ask the company to confirm that the engineer they send is registered for LPG, and check the ID card when they arrive.

If you would like us to look at an LPG boiler, send us the details and say clearly that it runs on LPG. We will tell you before booking whether we can send an engineer registered for that work, rather than finding out on the doorstep.