There are several benefits of a combi boiler over a traditional boiler system:

• It is compact and saves space as no water tank is required
• It delivers mains-pressure water to faucets and showers
• Installation is generally quicker as less pipework may be required
• Running costs may be lower than a traditional system—especially with condensing combi boilers
• No preheating of water is required
• Relatively easy to maintain and repair

A combi boiler has two independent heat exchangers:

1. For the radiators (this is the primary exchange)
2. For the hot water supply (the secondary exchange)

The radiators receive hot water according to your heating settings and the boiler also heats water directly from the mains (clean water supply) when a hot tap is turned on anywhere in your home.

The best type of shower to use with a combi boiler is an electric shower or mixer shower.

An electric shower provides instantaneous hot water, retrieving cold water from the mains and distributing it around the system’s internal heating unit.

A mixer shower connects to both the hot and cold water supplies, adjusting water flow and temperature using a shower valve or the taps.

You should avoid power showers with combi boilers. Power showers have an internal pump and this makes them incompatible with combi boilers due to the additional force they create potentially leading to excessive pressure.

No, it is a myth that the flow rates (outputs of hot water) from combi boilers aren’t sufficient for use in larger homes.

Homes with five bedrooms, with a bath and two showers, regularly install combi boilers with no issues.

Besides, some combi boilers have storage capacity, allowing you to keep a small tank to store water that can be heated instantly.

Low water pressure can be a problem at peak water usage times in some apartment and tenement flats, but there may be some methods you can use to raise water pressure.

In most houses, a combi boiler operates without any issues because it is fed directly by mains water from the road outside the home and, therefore, receives mains pressure.

If you do suffer from low water pressure in your house because you are located on a hill, for instance, you may be able to install a main booster pump or create a break tank to improve pressure.

A central heating inhibitor is a maintenance measure for your boiler.

You add a chemical solution to the water to keep it working efficiently, prevent malfunctioning, and extend its life.

In particular, with metal piping and components, rust, limescale, and dirt can build up over time and may cause blockages and affect the performance of your boiler. This can also increase energy costs if your boiler starts to operate at sub-optimal efficiency.

With a combi boiler, it is important to add the central heating inhibitor to the system after it has been cleaned or received its maintenance cheque—usually annually at least.

Make sure the heating is turned off and the radiators are cool. Add the inhibitor directly into one of the radiators via the bleed valve or (in the case of the towel radiator) via the plug at the top.