Benefits of a Combi Boiler

Combis generates hot water as and when it is needed, avoiding running out of it. The hot water is at mains pressure, which is an advantage for showers.

Standard combis take 40 seconds to heat water and this is a considerable wastage of water. However, slightly more sophisticated combis have a device which restricts the flow of water until it is hot enough to use. Others (storage combis) keep a small reservoir of water permanently hot.

Standard combis provide maximum pressure through only one tap at a time. If you have two taps running the flow rate diminishes. This can be partly overcome with a high power or a storage combi.

Combi boliers are more effiecient as they do not need a tank to store and keep hot water. \the hot water is generated when it is in demand and stopped when the demand is no longer needed.

If gas-powered, very large combis or multiple combis impose a huge demand on the gas supply pipework within the house. If two combis are running simultaneously the installation has to be good enough that a gas hob etc does not go out and then fill the room with gas when the boilers shut off. It generally means separate gas feeds taken from as near as possible to the gas meter. Seek professional advice for pipe sizing.

The flow rate for *all* the appliances in the house is limited by the capacity of the rising main. Flushing a toilet may thus lead to the hot water temperature fluctuating, or even going cold. Do not install a combination boiler unless your rising main is sufficiently good - flow rate may not be adequate for washing machines/dishwashers that require a hot feed.

An airing cupboard is a godsend to some people for the final drying/storage of clothes. A combi dispenses with the cylinder and hence the space needed for it. However, if an airing cupboard is available, it may be possible to keep it warm by installing the boiler within it. The usual trick of putting a small radiator on the boiler's bypass circuit is not really adequate because, unlike other types of boiler, heat will only be available when the central heating system is needed, but not when only hot water is demanded.

An immersion heater cannot be used as an emergency backup in case of the boiler failing as there is no cylinder for it to go in. An instantaneous electric shower could be used although it would need its own water supply as it cannot be put in series with the combi's output. It certainly won't be as cheap as adding an immersion element to a normal cylinder and will need a beefier electricity supply.

Your combi boiler should be serviced anally to keep the system running efficiently and ensure safety.

At the service interval the system should be checked for gas leaks as well as checking the output flue to ensure that the gases can escape safely. Keeping your combi boiler services annually and maintained will ensure your boiler runs efficiently and safely.

Your service should not run into more than 180 GBP and make sure that the engineer is gas certified ideally from a reputable company.