What type of boiler should I choose? 

There are three main types of boiler: Combi, Heat Only and System. NOTE: Combi is short for Combination. A Heat Only boiler is also referred to as a ‘Conventional’ boiler or a ‘Regular’ boiler 

COMBI BOILER 

A combi boiler is a single unit that generates all the heating and hot water for the home. There are no hot water tanks. 

HEAT ONLY BOILER 

A heat only boiler only provides heating. It works with a hot water cylinder. If your system is ‘open vented’ there will also be an expansion tank in the roof space. 

SYSTEM BOILER 

A heat only boiler only provides heating. It works with a hot water cylinder. If your system is ‘open vented’ there will also be an expansion tank in the roof space. 

COMBI BOILER ADVANTAGES 

Creates space when removing old hot water tanks. 
Lower maintenance costs – the integral heating and hot water functions are covered by the boiler manufacturer’s warranty/guarantee. 
No long wait times for hot water. 

HEAT ONLY BOILER ADVANTAGES 

Low replacement cost as heat only boilers are the cheapest type of boiler to buy. 
Works well with old radiators on an open vented system. Old radiators can leak if put ‘under pressure’, as is required when installing a new combi or system boiler. 

SYSTEM BOILER ADVANTAGES 

Good for properties that have a high demand for hot water, e.g. lots of showers, when paired with an unvented cylinder. An unvented cylinder can deliver good hot water flow rates to multiple outlets simultaneously. 
Lower maintenance costs, as more of the system’s components are integral to the boiler and covered by the manufacturer’s warranty/ guarantee. 

COMBI BOILER DISADVANTAGES 

They do not work well in properties with poor flow rates and/or poor incoming water pressure. 
Hot water flow rates are reduced when providing hot water to two or more outlets simultaneously. This is really only a problem in houses with two or more showers in use at the same time. 

HEAT ONLY BOILER DISADVANTAGES 

Only the boiler is covered by the manufacturer’s guarantee/warranty. This leaves lots of other system components, e.g. hot water tank, pumps and valves, subject to replacement and breakdown. 

SYSTEM BOILER DISADVANTAGES 

Hot water flow rates depend upon good incoming mains water pressure, if the pressure is poor then internal flow rates will be poor and a vented cylinder should be considered. 
They require more space. If you are swapping a combi boiler for a system boiler you will need to find an appropriate location of the hot water cylinder. 
To discuss what boiler type would work for you, your home and your family, please get in touch with Ox Heating Hull. Ox Heating are based in Hull, East Yorkshire and are available for projects and call-outs across Hull, Holderness, West Hull Villages, Cottingham, Beverley and the wider East Yorkshire area. Just call Steve to book an appointment today. 
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