Electric Combination Boilers

We get asked every day if we could provide a quote to supply and install an ‘electric combination boiler’.

We do not install ‘electric combination boilers’ for the following reasons, firstly I would like to explain how a gas combination works compared to an electric combination boiler.

Gas Combination Boiler

gas combi boiler

Mains Cold water enters the boiler at approx. 4 – 6 degrees (winter) to 12 – 15 degrees in the summer, the gas boiler then heats the cold water up to approx. 35 – 40 degrees in seconds, as the cold water passes through a plate heat exchanger which is heated to approx. 80 degrees, degrees, the 80 degree heat is transferred to the cold water.

This is tried and tested technology and has been in use in people’s homes for over 30 years and has hardly changed.

Electric Combination Boiler

*please forgive us, the actual pic below is a gas boiler and is for illustration purposes only

electric combi boiler two

Once the internal hot water tank has been used up the tank will take approx. 30mins to reheat. In a busy household this will likely cause problems. Also as the hot water is heated up via an element, similar to your kettle (check out the lime-scale in it) the internal tank suffers badly due to lime-scale in hard water areas, please be advised that lime-scale voids the boiler warranty.

Another problem with electric combination boilers is the flow rate.

If a customer has high flow rate (flow rate is the amount of water that flows out of the cold mains drinking water, this is calculated in litres per minute, i.e. in 1 minute how much water came out of your tap, it obviously varies throughout London, depending on the age and type of property.)

Example – this electric boiler is rated by the manufacturer to provide 35 degrees hot water at 12 litres per minute.

electric combi boiler three

If you had a flow rate of 18 litres per minute, 18 Lp/min would enter the boiler and 18 Lp/min would leave the boiler, however as the boiler can only heat 12 litres per minute, then only 12 litres out of the 18 will be heated, thus causing the hot water to be barely warm.

When electric combination boilers are more reliable then we will install them.