A heat only boiler does exactly what it says on the tin, it literally just heats water in the heating circuit. There is no internal pump or expansion vessel like in a system boiler.
It is usually found on older systems used in conjunction with water tanks in the loft. Most people with this system in a 2-3 bed house choose to upgrade to a combi system when the time comes to replace the boiler, as it offers more benefits in smaller homes.
This type of boiler is ideal for large homes as you can put on a external pump and expansion vessel designed specific for the size of the property. It can also used in conjunction with both vented and unvented cylinders. It can be used on both pressurised or gravity fed central heating systems.
If you need a new boiler and you need a new boiler look no further for a installer. Here are some reasons why you should pick Boilers 4 Essex:
Your One Stop Shop For Gas, Plumbing, Heating And Electrical Work
Combi boilers are ideal for homes with one bathroom. Usually fitted in 1-3 bed homes.
The advantages of a combi boiler is it only makes hot water when you need it and that it takes care of both heating and hot water with no external controls.
Quite simply its easier to maintain as there is a lot less to go wrong. Every thing is contained with in the boiler itself, so if you get a get a new combi with a 10 year warranty for example you know you won't be paying for any breakdowns on your heating for 10 years. With both system and heat only boilers there are a lot of components external to the boiler that are not usually covered by a manufacturers warranty.
A combi boiler also takes up a lot less space as there is no hot water cylinder.
A system boiler is similar to a heat only boiler except for the fact it has a build in internal pump and expansion vessel. It also needs a sealed pressurised heating circuit to work (no feed and expansion tank in the loft).
It is usually used in conjunction with a hot water cylinder and as these are a more recent boiler design you often see them with unvented hot water cylinders, but they can also be used with gravity fed vented cylinders.
This type of boiler used with an unvented cylinder is a good option for a home with multiple bathrooms with high hot water demand.