Domestic Boiler Chart

Use this simple chart to determine whether you need a Combination boiler(combi) or a System boiler.

We would always recommend that you consult a corgi registered gas engineer as we cannot be responsible for incorrect selection of boiler appliances and this chart is meant as a guide only.

 

Boiler Type	Limitations	Advantages	Typical Situation
System Boiler	Limited only to the size of the hot water storage vessel and the heating requirements of the property.	Ample hot water at all times. No limit to number of taps. Can be used on Conventional systems.	Replacement for Conventional systems. Ideal for larger properties, where there may be lots of taps and occupants. Used in conjunction with a pressurised or open vented cylinder.
Combination Boiler	Limited to the heating requirement of the property and the boilers hot water flow-rate. The more people using hot water at any one time, the less the performance.	Not paying to keep a store of water hot. Produces hot water on demand. Low fuel costs. All main components are built in to the boiler.	Flats or houses with few bathrooms and sinks. Low occupancy premises.

Note: Due to government commitments to the reduction of greenhouse gases and the use of fossil fuels, from April '05, all new and replacement gas boilers in England and Wales are required to be of high efficiency (condensing) with a SEDBUK rating of A or B.