What Are the Different Types of Central Heating Boiler Systems

NoNonsenseNinja

June 4, 2019

When it comes to central heating boilers there are basically two main types available: conventional or combination (combi) systems.

Conventional (or traditional) boiler systems feature:

A boiler
Hot water cylinder and pump that feeds the taps and radiators
Usually two cold water tanks, a large storage cistern and a smaller feed and expansion tank

The benefits of a conventional boiler system include:

Faster hot water flow rate than combination boilers so you can run more than one hot water tap at any time. Also, if you have several bathrooms or showers (or even a power shower) then you can specify a larger capacity hot water cylinder and pump
Conventional boilers will need space for the water cylinder which is usually an airing cupboard. This provides a great space for drying clothes.
Water heating does not rely on the boiler alone but can be heated using the independent electric immersion heater, so great as a backup. Using the immersion heater for long periods will be costly though
Conventional boilers are also ideal if your mains water pressure is low as the system has its own hot water tank and pump

However, you should also consider the negatives associated with conventional boilers:

Space. You will need room in your loft/attic for the cold water tanks and also space for the hot water cylinder
Hot water heating is not instant so you will have to plan in advance (or set the timer) if you need to use hot water
The amount of hot water you have is limited to the size of the hot water storage cylinder. Once this is emptied you will have to wait for the cold water to reheat. You can get around this by installing a large capacity hot water storage tank

A combination (or combi) boiler system differs from a conventional boiler system in the following ways:

A combination (or combi) boiler is one unit that provides water for the central heating and instant hot water for the taps
No separate storage tanks are required

The advantages of combi boiler systems are:

Space! With no requirements for separate hot and cold storage tanks, space is freed up in the attic or loft and there is no need for a hot water tank cupboard
Efficiency. Combi boilers are very efficient as they only heat the hot water as required, so you are not paying to heat up the full hot water storage tank. These means you will also never run out of hot water
The water is heated directly from the mains supply so your hot water pressure will be at a similar pressure. This is good if you have high main pressure but not so good if your mains water pressure is low
Installation cost may also be cheaper as there are no tanks and less pipework to install

As with any combination type syst,em there are always negatives and for combi systems these include:

If you are using more than one hot water tap at a time then the pressure will be reduced to each tap. This is more of a problem if you supply water pressure is low
The system does not have a hot water tank so while this is great for saving space it also means you cannot have a warm airing cupboard for clothes drying

Central heating boiler brands

There are several leading boiler brands that supply the UK market:

Boiler installation: what to consider?

Boiler installation and service When it comes to boiler installation you should consider the following:

Any gas boiler installation in the UK must be completed by a Gas Safe registered installer.
Make sure the installer understands your requirements. This should be costs and budget (installation and running costs), existing system installation, space requirements and hot water requirements. We would also advise that you think about future scenarios as well, will you install a more powerful shower or add an extra bathroom at some point?
Try and get feedback from previous customers.
Ask what back up support and service they will offer, especially in the first few weeks following installation.