COMBI

What is a Combi?

A Combi is an abbreviated word for the name Combination.

It combines what used to be an old style instant water heater which heats the water as the tap is turned on, and it is big enough to run the central heating.

With a Combi you generally have no hot water storage tank and no tanks in the loft.

The water comes straight from the mains to be heated.

What to Check When it breaks down.

Low pressure.

The most common cause of a breakdown is when the central heating water pressure becomes too low to operate. This is usually indicated by a dial somewhere on the boiler and should be pressurised to number 1. Using a gadget, which we in the trade call a filling loop, does this. This is attached to the mains water supply and to the central heating. With care open the valve and top up the system.

Overheat reset.

The boiler may have locked out on overheat. Check your manual to find the reset button which usually needs to be pushed in.

Power Off.

Check to see if the boiler isolating switch has been turned off by mistake.

Pump Stuck.

If you feel competent to check the pump, see our section on stuck pumps.

Advantages and Disadvantages of a Combi.

ADVANTAGE

Combis are ideal for flats and for where space is at a premium.

They heat the water on demand so there is no chance of the tank running dry because it does not have one.

The radiators generally get hot very quickly because the boiler has to be big to give you enough instant hot water.

They are easy to fit and it saves time and money.

There are no tanks to freeze up.

There is no waste of heat as it has no tank to heat up.

DISADVANTAGE

There are many makes on the market and the makes also have many models. Trying to get spare parts can be difficult.

If they break down you have no heat or hot water.

There are many water connections in the boiler, which is also combined with many electrical components. (Not a very good combination).

In hard water areas they have a tendency to scale up.

The expected life of a Combi is about 10 years.

You have to wait for the water to get hot when you turn the tap on. (Most models).