What is a condensing boiler?

All boilers fitted in the UK have to be condensing by law due to their increased efficiency, standard efficiency boilers were far more expensive to run and far worse for the environment and were therefore made illegal. Condensing boilers work by condensing the gasses emitted through the flue, this causes the latent heat to be recovered, which is then used to heat your radiators and provide you with hot water at a much lower cost to your bank balance and to the environment. Condensing boilers have to have an energy efficiency rating of 90% and above. Condensing boilers require a plastic waste pipe which transports the water vapour produced from the condensing process from the boiler to a drain.

Types of Condensing boiler:

Combi boiler (combination boilers)

Combi boilers combine a hot water system and a central heating system in one compact unit, they do not require a hot water cylinder, header tanks or any external controls with the exception of a room stat. The hot water is instantaneously heated up through a small heat exchanger contained within the boiler, cold water from your mains supply goes in to the boiler and leaves as hot water, the central heating is pumped around the system via a diverted valve when required.

Advantages of a combi boiler:

• No hot water cylinder or header tanks saving space in your home
• Instant hot water
• Compact in size
• High in efficiency
• All of your heating and hot water components in one unit

Disadvantages of a combi boiler:

• A Combi can only produce 12-16 litres of hot water per minute meaning that you can’t for example have 2 showers running at the same time
• With some faults you will lose both your hot water and heating until repaired

Regular/heat only boiler

Regular or heat only boilers as they’re also known operate in the same way regardless if you select heating or hot water. The boiler fires and the heat from the burner is then pumped to a zone valve which either diverts it to the central heating, hot water or both depending on the users demands.
In addition to the boiler itself you will also require a hot water cylinder, external pump, zone valves and additional pipe work to fill your hot water tank and heating system when required.

Advantages of a heat only/regular boiler:

• Less pipe work required for the installation of the boiler
• Smaller in size than Combi boilers
• If your central heating fails you can install an immersion heater inside your hot water cylinder to ensure you still have hot water(works like a big kettle)
• Much higher flow rates than a Combi boiler ie you can run more than one shower if required

Disadvantages of a heat only/regular boiler:

• A large hot water cylinder is required
• An external pump and zone valves are required
• Complex wiring is required for the external controls
• 2 header tanks are required (one to fill the hot water tank and one to fill the central heating if and when required).
• More perceptible to air locks due to the open header tanks feeds and vents
• Poor pressure from the hot water if the cylinder can’t be located high enough
• More perceptible to sludge problems

System boiler

A system boiler is the same as a regular/heat only boiler except it is a sealed system, meaning header tanks aren’t required and the external controls are integrated inside the boiler and therefore covered by manufacturers guarantees.

Advantages of a system boiler:

• less perceptible to sludge and air locks due to being a sealed system
• Controls covered by your manufacturers warranty due to them being contained within the boiler

Disadvantages of a system boiler:

• More expensive to install if converting from a heat only/regular boiler to a system boiler
• System boilers require an expansion vessel and prv (pressure relief valve) which increases cost and potential maintenance problems

If you would like boiler installation advice on any of the above types of boiler and live in the Newcastle,Sunderland, Gateshead or surrounding areas, then you can contact one of our boiler installers who would be happy to talk through your requirements by clicking here