If you have a gas boiler, or are thinking about setting one up, it is essential that you understand how it works. This will help you to work out if it’s working correctly or might have developed a fault.

However information on boilers can often be confusing.

To help you understand your boiler and how it works, we’ve come up with 8 gas boiler terms and definitions you have to understand.


A flue resembles a chimney. It’s a passage or pipeline that supplies a route for your boiler’s exhaust gases to move from your boiler to the outside.

As exhaust gases can be a harmful health and security threat, it is essential that your flue is secure and ends at a suitable point outside your home.

Condensing boiler

A condensing boiler uses exhaust gases to heat water and enhance its energy efficiency. According to Building Regulations, all boilers set up after 1st April 2005 needs to be condensing boilers unless there is adequate reason not to. A Gas Safe registered boiler engineer can check your home and tell you if there’s any reason you cannot install a condensing boiler.

Circulation rate

The flow rate is the quantity of gas or liquid moving through a channel or pipe over a particular time period. It’s normally determined in cubic meters per second (m³/s).

Cold water tank

The cold water tank is the part of your boiler installation that stores cold water before it’s heated. Cold water tanks can be fairly huge and are part of conventional boiler installations.

Hot water cylinder

A hot water cylinder is the part of a boiler setup that heats water. Hot water cylinders are part of system and traditional boiler setups.

Gas Safety Register

The Gas Safety Register is the UK’s gas safety watchdog. It’s imperative that you work with a Gas Safe registered engineer if you need any gas work completed in your home.

Carbon monoxide (CO)

Carbon monoxide gas is a gas that’s produced from the partial combustion of gases like your boiler fuel. It’s colourless and odourless and can be fatal if inhaled in large quantities.

To secure yourself against carbon monoxide exposure you must set up a carbon monoxide gas detector. You should likewise get all gas home appliances, including your boiler, installed and serviced frequently by a Gas Safe registered engineer.

Energy provider

Your energy provider is the company that supplies electrical power or fuels like gas, oil or LPG (liquefied petroleum gas) to your house.

So now you should understand a couple more gas boiler associated words and expressions. If you’re trying to find somebody to take a look at your gas boiler, or are looking at setting up a new one, we can assist. Complete our online form and we’ll put you in touch with as much as 4 registered boiler engineers in your location. Or to learn more about different kinds of boiler, have a look at our information on combi, system and conventional boilers.

Get up to 4 Free Quotes from Combiboiler.net