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boiler controls and pressure gauge

A guide to how your boiler works and how to use it efficiently?

By Marta Moses | Posted May 09, 2018

The most common way currently to power central heating in your home is with a gas-powered boiler. These come in a variety of different types but the most common are combi, conventional and system boilers. In this guide, we explain the different types of boilers, how they work and how to best look after them. 

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What are the main types of boilers?

Combi boiler 

A combi (or combination) boiler is by far the most common type of boiler. A combi boiler system's simple design requires little space in your home and supplies hot water directly to your taps or radiators without the need for a storage tank.

The chief advantage of a combi boiler is its economy. Because it supplies hot water on demand, you only ever pay for what you use. So it means it's highly energy-efficient and also financially efficient.

Conventional boiler 

Unlike a combi, a conventional (or regular boiler) uses two water tanks – one to draw the supply from the mains and one to feed the system and manage the expansion of the heated water.

Conventional boiler systems are relatively complicated and take up a lot of space and they store your hot water in a cylinder instead of supplying hot water on demand, which could be a drawback to some people.


System boiler 

Like combis, system boilers take water directly from the mains. Unlike combis though, they store the water they heat in a tank. So although a system boiler uses less space than a conventional boiler system, it's more complicated than a combi and needs more room.



Boiler controls and how to use them

Some boilers have so many features they can be hard to understand. Here we’re taking you through some of the most common dials and controls on gas-powered boilers. If you’re in any doubt about changing controls on your boiler don’t hesitate to call a professional plumber as you could cause some damage.

Pressure gauge

Your central heating is a closed system – meaning it recirculates the same water around the pipes and radiators in your home. That water expands when it heats up, so one of the most important things to look at on your boilers is the pressure gauge. This will show you (in the measurement metric ‘bar’) how much water pressure is in the system. Too much and you could risk pipes or parts of your boiler bursting. Too little and your boiler won’t be able to circulate enough hot water to your radiators – especially to those higher or further away from the boiler.

When your heating has been on for some time, and the water in the system has expanded, you should see this pressure gauge rise towards a mark. This mark will be the optimal pressure setting for your system.

If it is too low, your central heating won’t be working as well as it should. This could be because:

  • Your radiators have air in them. This is fairly common and can be solved by bleeding the radiators. You can check by feeling the tops of your radiators – if some of them aren’t as hot as the bottom part, that could mean you have air in the system.
  • There’s a leak in your central heating somewhere. This needs to be diagnosed and fixed as soon as possible by a professional.

If it’s too high, it means your system is too full. Try bleeding some water out of your radiators to bring the pressure down. If you're not sure how to bleed your radiator, always ask a professional.

Power switch/button

There will be a way to turn your boiler on and off – that could be a switch or a button. Generally, boilers are designed to stay on for long periods, so you shouldn’t have to use this. However, if you’re going away for a long time you might want to stop your boiler from coming on at all, and this power button is the most effective.

Central heating dial

You can control how hot your boiler will make the water in your central heating system. Generally, this will be set quite high, as you’ll have thermostats around the house controlling when the boiler turns off and on or when the radiators take hot water in.

There’s usually one of these for hot water – you should see a picture near the dial showing which is which.

In most cases, you won’t need to touch these.

Eco button

Some boilers, like the Worcester-Bosch Greenstar 30CDi (combi), have an ‘eco’ button. When this is pressed (the light is on) your boiler won’t preheat the water in your hot water pipes.

Although this means you’ll have to wait a short while until you have hot water from your taps you’ll only use gas when you need it.

Could your boiler do with a service? 

It’s important to get your boiler serviced regularly to check for any worn parts or potential problems and make sure its working efficiently. We offer a boiler cover that comes with an annual boiler service.

Replacing your boiler

If your boiler is getting on a bit, a new boiler is likely to be more energy-efficient, quieter, more reliable and have more features. 

It's also worth considering boiler alternatives, such as air source heat pumps or modern electric heaters, which are very efficient and low carbon. 

Protecting your boiler with boiler insurance

Boiler and central heating not working on a cold winter's day is really the last thing any of us needs. Getting boiler and central heating cover can prevent this from happening because your boiler gets serviced regularly. And, more importantly, should your boiler break down, the insurance provider will send out a certified engineer to deal with it.

We offer a number of boiler maintenance and insurance plans. Be sure to get your boiler and heating all ready for winter.

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