We regularly get enquiries from customers asking for Electric Combination Boilers as an alternative to Gas Combination Boilers. What people do not understand is that the two products work in different ways and look completely different.

People assume that what is called an “Instantaneous Water Heater” is an Electric Combination Boiler however this is not the case. Most Instantaneous Water Heaters are designed to be installed at a point of use for single outlets such as a bathroom basin or kitchen sink and only provide hot water (not suitable for baths) and not heating as well. However, they work in a similar way to gas boilers in the sense the heat the water as it goes through the unit. The KW ratings range from 3kw – 12kw.

Gas Combination Boilers are normally wall mounted systems that provide hot water to both a heating system and to multiple outlets such as sinks, showers and baths. They can cope with providing hot water to multiple outlets including baths as they have a much higher KW rating and can heat the water to a higher temperature much faster than an instantaneous water heater can.

Electric Combination Boilers can provide water to both your heating system and to your multiple outlets the same way a Gas Combination can however they do this in a completely different way and are large floor standing units. An Electric Combination Boiler consists of two parts in one casing. One being an Electric Flow Boiler such as a Heatrae Sadia Premier Heat. The other is an Indirect unvented cylinder such as the Joule Cyclone Air.

The flow boiler part of the system provides the hot water for the heating system but also indirectly heats the water within the indirect unvented cylinder. In case you are not aware how an indirect unvented cylinder works refer to the link below, this should answer any questions you have.


We offer two models of electric combination boilers. One is the Heatrae Sadia Electromax.

This comes in a 9kw and 6kw version and has a tank capacity of 180 litres. There is also a choice between either a model that is suitable for a standard radiator heating system or a model that is suitable for an underfloor heating system. These units come complete with everything needed to install them.

The other model we offer is the Advance Applicance ECB210


This comes with a rating of between 6kw and 10kw depending on which model you purchase and has a tank capacity of 210 litres unlike the electromax there are not different models for radiator and underfloor systems, it can be installed to work with both.

To sum up the main differences between an Electric Combination Boiler and Gas Combination Boiler are: -

  • Electric ones are large floor standing units and gas are usually wall mounted.
  • Electric ones consist of a boiler and storage tank whereas gas ones heat the water as it goes through the unit and do not have the storage tank.
  • Running costs are higher on Electric than it would be on Gas as electric is a more expensive fuel.


Need any more information? Just call one of ourexperts on 01934 253600 on use the online facility at https://electricaldealsdirect.co.uk.