Guide to choosing the right boiler for your home

Choosing the right boiler for your home (or office) and heating needs can be challenging.

You want to make the right decision, but you’re not sure what needs to be taken into consideration and the options on offer to you. If that sounds familiar, this information  will help!

What types of boiler are there?

Essentially there are three types of boiler, these are:

• Combination boiler (often referred to as a “Combi”)*
• System boiler
• Regular boiler

*A combination boiler can be a Standard Combination boiler or a Storage Combination Boiler.

What’s the difference between the types of boiler?

A Combination boiler is both a highly efficient water heater and a central heating boiler – combined within one compact unit. There is no need for a separate hot water cylinder.

Because the hot water is fed directly from your cold water main pressure it is generally better than an open vented hot water cylinder where the hot water is fed from water tanks in the loft.

These boilers are cheaper to install than a separate boiler and cylinder, but performance can be limited. Generally speaking their performance figures are based on a single hot water outlet being used at a time, therefore – it is essential the boiler is suitable for the size of the property and the amount of people using it.

A Storage Combination boiler is similar to a standard combination boiler with the exception that it has an additional storage tank hidden within the boiler. The storage tank or “heat store” as it is sometimes called, preheats water which offers a higher flow rate and this means the boiler can cope with higher demand on it.

A System boiler includes a pump and an expansion vessel. The presence of the expansion vessel removes the need to have a header tank (or “expansion tank”).

A header tank is a small tank which typically lives in your loft and keeps the water in your heating system topped up and allows water to expand when it is heated by the boiler. With this set up, a separate hot water cylinder is needed for your hot water. 

A Regular boiler is a more traditional unit and has no pump or expansion vessel. It requires a separate pump to be fitted which can often be housed in your airing cupboard. This boiler can also have an external expansion vessel fitted so you don’t need a header tank (“expansion tank”) in the loft. A separate hot water cylinder is needed for your hot water, this can be positioned in an airing cupboard next to the pump.

Can these boilers run any type of fuel?

Yes. Most boiler manufacturers offer a range of boilers which can run on natural gas, oil and LPG.
Renewable energy units are regarded slightly differently and although they may look like “normal boilers” we don’t generally categorise them in that way.

How do I choose which boiler is right for me?

Working on the basis that you have “fuel” at your property which is either natural gas, or oil or LPG, via storage tanks, there are other factors to

• the size of the property
• how many people live there
• how many bathrooms/ensuites
• the pressure of your mains cold water
• location of the boiler

Another consideration is the required flow rate for your hot water – ie if you have a large shower that needs a high flow rate you will need a hot water supply that can cope with that level of demand.

The above is intended as a guide only. The overall design of your system will need to be taken into account in order to decide what is the best option for you.

Should I choose a boiler based on cost?

Obviously if you are working to a budget this will limit your purchasing options slightly, but generally speaking you should buy the best boiler you can afford.
In terms of the running cost of a boiler that will depend on the following:

• quality of the boiler
• type of controls connected to it
• if it’s the right boiler for your requirements in terms of specification and size
• if the boiler has been installed correctly as part of your heating system design

It is important that you weigh up the cost of the initial boiler purchase (installation) against the ongoing running costs, as invariably a cheap boiler will have higher running costs which would make buying it more costly in the long run.
It’s also worth considering that if you own a particularly large property you may be better off having two boilers installed. Again this will depend on size, type, layout and usage of the property – however, in most cases two single boilers can be run more efficiently than one large single boiler, even if buying just the one was cheaper.

For example:

1 x boiler with a 60kw output* can modulate down to 17kw  

in comparison to-  

2 x boilers at 30kw output each can run as low as 8.8kw as both boilers do not need to be on at the same time when demand is low. 

*based on a Viessmann 200W boiler 

How do the costs compare across the different boiler options?

Prices vary depending on a number of factors:

• whether you are changing your boiler – like for like
• whether you are upgrading or updating your heating system,
• and which type of boiler is best suited to your requirements