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Gas / Heating engineers - what you need to know

The most common job a heating engineer does is replace boilers. You should always use a Gas Safe-registered heating engineer or plumber to install your new boiler.

To get started, they’ll arrange a time to come round and look at your current setup, so they can measure up and give you a detailed quote. They might also give you price options for different boilers and talk about the brands they recommend. An experienced heating engineer will have a broad knowledge of boilers and will be able to tell you which ones provide the best value, which are most energy efficient and which are the most reliable.

Once you’re happy with the quote, they’ll fix a date to come over to install the boiler. They’ll usually supply the boiler themselves and be transparent about the cost. The bulk of the quote will be paying for the boiler itself, with labour on top. You can expect the installation to take the best part of a day overall.

The engineer will first remove your current boiler and any pipework that needs to be disposed of. They’ll then make all the adjustments needed to fit and mount the new boiler. If you’re having your boiler moved, then they’ll also need to drill out holes for ducting from the boiler and tidy up the location of the previous boiler.

Once the new boiler is installed, with gas and water connections made, your heating engineer will test the boiler to make sure that it heats water efficiently and that it works with any central heating that you have installed. Make sure they talk you through the basic settings on the boiler, such as the thermostat and how to increase or decrease the pressure in the boiler as needed. The engineer should also show you how to ignite the pilot light.

Combination (combi) boilers

The combi or combination boiler is the most popular kind of boiler that heating engineers install. They’re energy efficient, provide hot water on demand and will last a long time if they’re cared for properly. Water comes into the boiler directly from the mains, and is heated quickly and efficiently, before being piped to showers, taps and radiators. There’s no need for a separate hot water cylinder or tank in the loft – which makes it cheaper to install.

Conventional or regular boilers

A conventional boiler, or regular boiler, heats water in a tank that’s usually kept in the loft. The boiler heats the water in the tank, which is then piped to showers, taps and radiators. It’s good if you have multiple bathrooms that may be in use at the same time, as this system doesn’t have the problems of getting suddenly very hot or very cold, which can sometimes happen with a combi boiler system. It provides central heating efficiently too.

System boilers

A system boiler is a variation of the conventional boiler and can be confused with this more common type of boiler, so do ask your plumber or heating professional about which system you have if you are in any doubt. Your engineer should come to look at your old boiler and measure up for the job anyway, so this is the time to ask questions or advice on boiler types.

The main difference with the system boiler is that it heats water straight from the water supply, rather than relying on a cold water tank feed from your loft. This makes for more efficient hot water supply and also does away with the need for installation and maintenance of a cold water tank. For this reason, the installation of a system boiler can cost slightly less in terms of labour costs.

Costs for common boiler installation jobs

Planning permission for heating engineer jobs

If the work is internal then planning permission isn’t normally required for installations of boilers or heating systems. However, if you live in a listed building you should check with your local planning authority.

If the installation requires a flue outside, it will normally be permitted development if certain conditions are met. See the Planning Portal for more detail.

Insurance for heating engineer work

As always, any good tradesperson should have public liability insurance, which protects against any accidents or damage to your home.

Building regulations for heating engineers

If a heating system or hot water system is to be replaced then an application may not be required, and, if it is required, it may not be necessary to apply in advance of carrying out the work. See the full details at the Planning Portal.

Questions you should ask a heating engineer

• Do they have public liability insurance?
• Are they Gas Safe-registered? (They’ll have a valid ID if so).
• What are the pros and cons of the three main boiler systems (combi, system and conventional).
• What is the cost price of the boiler you choose.
• Which boilers are the most efficient, reliable and easiest to maintain?

See the latest questions that homeowners have been asking heating engineers.

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