Boiler Guide

Thinking about a new boiler? Should you retain your existing set up or install a new system? There are three main types of heating and hot water system set up. We give some straight forward explanations below with pros and cons of each. To find out how much it will cost to replace one of these boilers, view our Guide to Boiler Installation Costs.

What is a combi boiler?

A combination boiler (or “combi”) is a compact, single unit that generates all the heating and hot water needed for the household.

A combination boiler heats water directly from the cold mains instantaneously. This is different from traditional systems which stores hot water in a tank in advance of use.

A combination boiler does not need a hot water cylinder or tanks in the loft. Everything is done through a single, usually wall-hung, unit.

What is a regular boiler?

A regular boiler (sometimes referred to a traditional, conventional or heat-only boiler) works with a hot water cylinder. These are open-vented heating systems, i.e. there is an expansion tank and cold water storage tank in the loft.

There are many benefits to retaining such a system. The cost of replacing the boiler is low. Header tanks of water also provide good flow rates, which is perfect for households where a lot of hot water is used simultaneously, for example showers in the morning.

This set up should definitely be retained where:

  1. The radiators are quite old. Older radiator systems that are put under the high water pressure delivered by system or combi boilers may leak.

  2. The property’s incoming water pressure is poor: System or combi boilers use the incoming mains directly instead of storing water in the loft. Poor incoming mains water pressure will lead to very poor flow rates to hot water outlets, the exact opposite effect of a header tank in the loft.

What is a system boiler?

Like regular boilers, system boilers work with a hot water cylinder. Unlike regular boilers, the system is not open-vented, i.e. there are no tanks in the loft, and all of the components that would normally be outside a regular boiler (pumps, valves etc) are integrated into the boiler.

These are a modern version of the Regular boiler and are often installed along side unvented hot water cylinders. They are good for properties that have a high hot water demand however good hot water flow rates depends upon good incoming mains water pressure.

Which is the right system for me?

Much of our installation work is just swapping out the old boiler for a new one. By and large householders are very happy with their existing set up and there seems little sense taking out functioning equipment (hot water tanks, header tanks etc) when only the boiler needs replacing.

The reasons for wholesale conversion to a new system are often to free up space (taken up by tanks), to replace an old back boiler with a standard boiler or to improve the guarantee or warranty cover on equipment installed.

For example, the guarantee or warranty on a regular boiler will only extend to the boiler, not the tanks, valves and pumps external to it. A combination boiler on the other hands has everything integral to the boiler, so the vast majority of the system is covered.

If you do wish to convert to a combination boiler system speak to our attending engineer about its suitability for your property.

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