21 July 2020 6 min read

Top 10 Most Common Boiler Questions Asked in 2020

Boilers are a 'hot topic' this year and they are a heating component that many people have questions about.

In this article, we answer the most common questions about boilers which, we hope, will improve your knowledge and help you feel more confident about choosing the right boiler for your home.

1. Which boiler is best?

The most common type of boiler installed in UK homes is the gas-powered combi (or combination) boiler. In fact, over 70% of us who have a central heating system in our homes have a combi boiler.

In simple terms, a combi boiler is combination of an efficient water heater and a central heating boiler. This type of boiler is so popular because there is no need for a separate water tank, saving space and providing all your hot water and heating needs in one unit.

2. What boiler do I need?

If you have a standard central heating system in your home involving a gas powered boiler and a network of copper pipes feeding into radiators, then the most convenient option for you is the combi boiler.

However, as combi boilers rely on access to the mains gas supply, they may not be the best option if you are off-grid, in a remote location or in an apartment block without gas.

In this case, you may want to consider an electric boiler which, in effect, acts as a water heater for your shower, bath and hot taps.

3. How boilers work?

A combi boiler works by efficiently providing hot water to your radiators and hot taps without the need for a separate water tank.

These efficient boilers provide hot water only when needed, as opposed to the old days where an immersion and water tank would sit heating water that may or may not be used.

A combi boiler springs into action when a hot tap is switched on, igniting the gas burner. Water is taken from the mains and submitted to the heat transfer system which heats up the water almost immediately.

Combi boilers have separate controls for the heating system, so you can comfortably have your heating running and take a shower with no delay or loss of efficiency.

4. Who fixes boilers?

For all boilers that are powered by gas, you must ensure that your plumber or heating engineer is officially listed on the Gas Safe Register. Anyone who works on a gas appliance must be on the GSR in order to carry out the work legally, so it's important you establish this by asking for identification.

Not only is it unsafe to allow someone unqualified or accredited to work on a gas powered boiler, you may also find if anything goes wrong that you are not covered by your boiler protection insurance.

If you have an electric boiler, or are considering having one installed, please make sure your installer is a qualified electrician and is legally accredited to connect electric boilers and heaters up to the mains electrical system.

5. Can boilers explode?

While it's rare for a household boiler to explode, boiler explosions certainly do happen from time to time.

A combination of high pressure, steam, gas and poor maintenance cause absolutely cause boilers to explode with often serious consequences.

Boilers are much like car engines in the fact that they need regular maintenance in order to keep working smoothly and effectively. It's always recommended, and for some warranties and boiler protection schemes it's mandatory, to have a qualified heating engineer perform central heating maintenance on your boiler and heating system every 12 months.

Though boiler explosions are rare, boiler breakdowns in the middle of winter are the most common side effect of a poorly maintained boiler and can often be very expensive to repair or replace.

Regular boiler maintenance will help minimise the chances of a boiler explosion, breakdown or carbon monoxide leak.

6. What boiler do I have?

If you have a fairly modern house, or an older house that has been modernised, and you have a conventional central heating system, it's likely you have a combi boiler. You'll be able to tell by looking at the boiler and seeing 5 copper pipes coming out the bottom. If you don't have a large water tank in the loft or in an airing cupboard, then that's further confirmation of a combi boiler.

If your home is quite old and never been modernised, but is on the mains gas system, you may have an old style conventional boiler. These will also usually have 5 copper pipes coming out the bottom but also require a large water storage tank in the loft and a water cylinder in an airing cupboard.

If you have a particularly large property, you may have a sealed system boiler. These can be identified by 3 copper pipes coming from the bottom and a separate hot water cylinder, likely in an airing cupboard.

In the end, if you're unsure what type of boiler you have then you should get a professional round to have a look. Not knowing what type of boiler is in your home can often suggest that the boiler hasn't been serviced for a long time, which is another important reason to get in a professional.

7. Is boiler cover worth it?

Boiler cover is a type of insurance that can help with boiler breakdowns, repairs and servicing. As a broken boiler can run into thousands of pounds to replace, it's definitely worth considering taking out boiler cover, especially as boilers tend to breakdown at the coldest time of year.

If you own your own home, then check whether boiler cover is included in your home insurance before taking out a separate policy. Many boiler cover policies also include annual maintenance, which helps to make the cover a very attractive and worthwhile consideration.

8. What boiler output do I need?

Combi boilers tend to come in four main output sizes:

24 - 25kw - For apartments homes of up to 10 radiators

28 - 30kw - For medium sized homes with up to 15 radiators

33 - 35kw - For larger homes with up to 20 radiators

40kw - For very large homes with radiators numbering 20 and above

Use the data above as a rough guide, but ensure you shop around and get several different quotes from installers to ensure you get what is needed for your home and the best value for money.

9. Do boilers use electricity?

Gas boilers tend to use only a very little amount of electricity to work, but this small amount of electricity is important for many of a boiler's functions.

Electricity is required to ignite the boiler when it initially comes on, as does the central heating pump. The dial displays and any smart controls rely on electricity to operate and the boiler fan, that extracts the flue gases outside, also requires a small amount of electricty.

Though, modern gas boilers require a electricity for many features to work, the usage is usually minimal and will hardly be noticed on your electricity bill.

10. Should boiler pressure rise when the heating is on?

There is a gauge on your boiler that displays the boiler pressure in bars.

When you switch your heating on, the pressure will naturally rise compared to when the heating is off. However, it shouldn't rise by too much. If there is a large rise in pressure then this could indicate a problem with the pressure release valve, the expansion tank or the boiler itself.

A healthy boiler pressure when the heating is switched on is between 1.5 - 2 bars.

A healthy boiler pressure when the heating is switched off is between 1 - 1.5 bars.

You should double check the manufacturer's manual to check the optimal pressure figures for your boiler and get in a professional if you are unsure.


• How often should you get a new boiler?

• What size boiler do I need?

• When was the last time your boiler was serviced?

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