Types of Boiler

Explore the different types of boiler commonly found in homes around the UK, with servicing, troubleshooting and upgrade advice.

Different Types of Boiler

In the UK, the most common types of boiler are; combi boilers, system boilers and conventional boilers. Each boiler type has it’s own advantages and disadvantages, and choosing the right boiler for your home is an important decision.

In this guide, we will explore each type of boiler in more detail to help you decide which is best for you. Our boiler engineers are also available to provide further advice and recommend the best boiler for your home – get in touch.

Types of Boilers in the UK - Combi, System and Conventional

 

Condensing Boilers

By law, every new combi, system and conventional boiler installed in the UK must be a condensing type. A condensing boiler doesn’t refer to a specific type of boiler, but instead relates to the internal parts of boiler, such as the heat exchanger. A condensing boiler captures heat that would normally escape into the atmosphere to help improve energy efficiency and reduce your utility bills.

The three main types of condensing gas boilers are combi boilers, system boilers and conventional boilers. Condensing boilers not only save you money on heating costs, but they are more than 90% energy efficient and reduce your carbon footprint too.

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Combi Boilers

There are a number of benefits of combi boilers, making them the most popular type of boiler found in homes around the UK. Also known as combination boilers, these boilers provide heating for both your central heating and the hot water that flows from your taps.

Combi boilers are economical and environmentally friendly, with many A-rated models available. They heat water directly from the mains, providing unlimited hot water whenever you need. They do not require a hot water tank, which is ideal for smaller properties.

How much does a Combi Boiler cost?

The average cost of installing a new combi boiler ranges from £800 to £2,000. There are a number of factors that influence the cost of installing a new combi boiler, including the system size you require, the manufacturer, energy efficiency and the company you choose to carry out the installation.

Find out how much boilers cost in your area? Request a quick quote!

Should I choose a Combi Boiler?

There are a number of reasons why combi boilers are the most popular type of boiler in the UK, but it is important to consider whether they are the right choice for your home. Below are a few considerations when choosing considering a boiler.

Combi Boiler Positives

  • Unlimited hot water and heating, direct from the mains.
  • Ideal for smaller homes due to compact size.
  • Powerful hot showers, without the need for a pump.
  • Easier maintenance and annual servicing costs
  • Less risk of pipes freezing.

Combi Boiler Negatives

  • Less suitable for larger homes.
  • Not compatible with all showers.
  • Less suitable for running 2 showers/baths at the same time.
  • Requires a certain level of mains pressure.
  • Leaks can cause a loss of water pressure.

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System Boilers

Below are a few general checks that can help identify common problems that cause no hot water from taps and showers. It may be possible to fix some of these issues yourself, whilst others are better left to an expert.

How much does a System Boiler cost?

Your boiler will need both a water supply and fuel supply (typically gas or electricity) to work properly. It can sometimes be easy to accidentally turn off these, and if your boiler has neither a water supply or fuel, you won’t receive any hot water.

A quick check can solve the issue and save having to call out a boiler engineer.

Why should I choose a System Boiler?

Just like checking the water and gas/electricity sup

Conventional Boilers

Below are a few general checks that can help identify common problems that cause no hot water from taps and showers. It may be possible to fix some of these issues yourself, whilst others are better left to an expert.

How much does a Conventional Boiler cost?

Your boiler will need both a water supply and fuel supply (typically gas or electricity) to work properly. It can sometimes be easy to accidentally turn off these, and if your boiler has neither a water supply or fuel, you won’t receive any hot water.

A quick check can solve the issue and save having to call out a boiler engineer.

Why should I choose a Conventional Boiler?

Just like checking the water and gas/electricity sup

Other types of Boiler

Whilst less common, there are a number of other boilers found in British homes. Below we will explore these other types of boilers in more detail.

How much does a Conventional Boiler cost?

Your boiler will need both a water supply and fuel supply (typically gas or electricity) to work properly. It can sometimes be easy to accidentally turn off these, and if your boiler has neither a water supply or fuel, you won’t receive any hot water.

A quick check can solve the issue and save having to call out a boiler engineer.

Why should I choose a Conventional Boiler?

Just like checking the water and gas/electricity sup

What type of boiler should I choose?

How much does a Conventional Boiler cost?

Your boiler will need both a water supply and fuel supply (typically gas or electricity) to work properly. It can sometimes be easy to accidentally turn off these, and if your boiler has neither a water supply or fuel, you won’t receive any hot water.

A quick check can solve the issue and save having to call out a boiler engineer.

Why should I choose a Conventional Boiler?

Just like checking the water and gas/electricity sup

Radiators Hot but No Hot Water

Gas Boiler Checks

The information below will help troubleshoot gas boiler problems if you have no hot water from your taps or shower. Whilst the information below will help you determine the issue, any work and repairs carried out on a gas boiler must be conducted by a Gas Safe registered engineer. 

If you need a gas boiler specialist, get in touch

Check other gas appliances

A useful place to start when troubleshooting a gas boiler problem is other appliances that use gas within your property. Turn on your gas hob or other appliance to ensure that the issue isn’t with the supply of gas to your property. This is a very quick test, but can save a lot of hassle if it is the underlying problem.

If your home has no gas supply, speak with your supplier directly to determine the issue.

Is the Pilot Light on?

A common cause of gas heating not working is the pilot light going out. The pilot is essential, as it is used to ignite the gas that heats your homes hot water. 

Your boiler manual will provide instructions on safely relighting your pilot light. Older boilers will often require a match to reignite the pilot light, whilst newer boilers will have an inbuilt igniter.

Gas boilers have a thermocouple, which is a safety device that detects whether a pilot light is lit and allows gas to flow. If the thermocouple does not detect a pilot light, it stops the flow of gas and prevents a leak into your home. If you are unable to reignite your pilot light, there may be a problem with your thermocouple and will need a boiler engineer.

Faulty Pressure Relief Valve

This valve regulates the pressure within your boiler, ensuring that it does not exceed dangerous levels that could cause your boiler to explode. When the pressure relief valve fails, the boiler will have a drop in pressure. If faulty, the valve will need to be replaced.

Hot Water Tank Too Small

If you are initially experiencing normal hot water, but then it becomes lukewarm or cool, your water tank may be too small. When a water tank runs out of water, the water coming out of the hot tank will be significantly cooler.

The most common solution for this problem is to install a larger tank. An alternative solution is to change the type of boiler in your property to one that instantly produces hot water on demand, such as a combi boiler.

Check for leaks

A leak within your homes central heating, pipes, radiators and taps can cause both a drop in pressure and water. Checking for leaks can be an important step, as not only can it impact your hot water supply, but can also result in structural damage to your home.

Central heating and hot water components, such as pipes and radiators, can be very hot, so be sure to take precautions when checking for leaks. 

Condensation on water tanks and boilers can sometimes be mistaken for a leak, however this is often due to the cold water entering the system and may not be cause for concern. If you have doubts, speak with a boiler and heating engineer.

Electric Boiler No Hot Water

Electric Boiler Checks

Below are a few general checks that can help identify common problems that cause no hot water from taps and showers. It may be possible to fix some of these issues yourself, whilst others are better left to an expert.

Read on to begin troubleshooting common causes of no hot water in homes.

Gas, Electricity & Water Supplies

Your boiler will need both a water supply and fuel supply (typically gas or electricity) to work properly. It can sometimes be easy to accidentally turn off these, and if your boiler has neither a water supply or fuel, you won’t receive any hot water.

A quick check can solve the issue and save having to call out a boiler engineer.

Thermostat Settings

Just like checking the water and gas/electricity supplies to your boiler, it is also a good idea to quickly check your thermostat to ensure your hot water and heating are turned on. Thermostats vary greatly between units and homes, and not all will have a function to turn off the hot water supply. 

It only takes a moment to double check that your thermostat has power (if it is battery operated), the hot water is turned on and that it is not set to the coldest setting. Try temporarily turning up the dial to see if that kick starts your boiler back into action and fixes the problem.

Reset the Boiler

Many boilers have a boiler reset button, switch or dial that can be found on the front of the unit. First, switch your heating and hot water off using your thermostat or central control, and then hold down the reset function on your boiler until it resets. Remember to turn on the heating and hot water again on your thermostat control.

If your boiler doesn’t have a reset button, or if using the reset function doesn’t fix the hot water problem, you can also try turning the unit off and on again.

Below are guides to resetting different boiler brands:

Frozen Pipes

During prolonged cold weather, pipes can freeze and prevent your boiler from working. The most common pipe to freeze is the condensate pipe, which takes waste condensation away from your boiler to a drain that is normally located outside.

You can try to unfreeze the pipe using hot (but not boiling) water. As there is no hot water from your boiler, use a kettle or your hob to heat water for the defrosting. You may need several attempts to clear the frozen pipe. However, if that still does not work you may need to call in a boiler technician.  

Boiler Clock/Timer

Even quite modern boilers won’t always update their clocks when changing between GMT and BST. If you set a timer to activate your heating and hot water throughout the day, the clocks being set incorrectly could be the cause of no hot water in your home.

This is one of the quickest troubleshooting tests to perform, and normally occurs when the clocks go either back or forward.

Has there been a recent blackout?

A power outage can sometimes through your boilers settings off. If there has been a recent power cut, it is a good idea to double check the settings on your boiler to ensure that it is set up correctly. As with the point above, check that your clock is correctly reset and that the hot water is set to on.

Diverter Valve Problems

If your radiators are hot but you have no hot water, it is most likely a problem with your diverter valve. The valve allows combi boilers to switch between heating your home and powering your hot water supply. When you turn on a hot water tap, the valve diverts heating away from the radiators and supplies hot water to the tap.

In short, if the diverter valve is not functioning correctly, your combi boiler will still have heating but no hot water. The valve may be faulty or stuck in the central heating position. A boiler engineer can diagnose and fix the fault, either repairing the valve or replacing it.

Low Pressure

Having sufficient pressure is an essential ingredient for system and combi boilers to function correctly. If your hot water pressure seems low, you can check the pressure using the dial on the front of your boiler. The pressure should typically be around 1-bar, and there may be an indicator to your boilers normal pressure range.

Low pressure can be caused by a number of problems, such as leaks in the system. Over time, combi boilers can lose pressure gradually. Your boiler manual will normally provide instructions about how to top up the boiler pressure. If you need to remove the boiler panel, it is recommended to use a qualified technician.

Airlocks

Air can sometimes build up in pipes, causing the hot water taps to splutter or produce no water at all. As air is less dense than water, airlocks occur in the high points of pipes, and can result in either a partial or complete blockage.

To fix the blockage, you can connect your blocked hot water pipe to a working cold water pipe. The pressure from the cold water tap will hopefully push out the airlock and resolve the issue (make sure the blocked hot water is open before turning on the cold water tap). If this does not work, you may need to drain the whole system, which can be done by a heating technician.

Ball Valve Float Problems

If you have an open vent boiler (a boiler with a water tank) the ball valve may be stuck, reducing or stopping hot water flowing around your property.

As the float is used to control water levels in the hot water tank, a low water level is generally an indication that there is a problem with the ball valve float. Fixing the stuck ball float may be as simple as moving the valve arm, but it is important to be gentle and check for anything that it may be caught on.

No Hot Water FAQs

Below are some of the most commonly asked questions we receive regarding no hot water from taps and showers. If you can’t find answers to your questions, please have a look around on our other pages or get in touch.

What causes hot water to stop working?

Problems with hot water from taps and showers can be caused by numerous issues. The most common causes of hot water not working include diverter valve faults, low pressure within the boiler system and frozen pipes. 

Our handy guide above will help you troubleshoot the most common boiler problems that result in a homes hot water not working. 

What's wrong with my boiler - no hot water?

There are a number of reasons your boiler may not be producing hot water. You can easily perform a number checks on your boiler to troubleshoot common issues and hopefully resolve the issue.

Below are a few ways to resolve common hot water issues:

  1. Check your gas, electricity and water supplies are on and working.
  2. Check your thermostat is correctly set and working. 
  3. Try resetting the boiler (if there is a button or function to do so).
  4. Check that pipes leading to and from the boiler aren’t frozen.
  5. Check the clock and timer on your boiler are set correctly.
  6. Check if you still have central heating. If you do, this indicates a diverter problem.
  7. Is there enough pressure in the boiler – check the dial on the front.
  8. If you have a water tank, check the ball valve isn’t stuck.

You will find more information about these troubleshooting methods, as well as specific information for gas and electric boilers above. You can also speak with one of our local boiler engineers to help diagnose the issue.

What is a diverter valve in a boiler?

The diverter valve in your combi boiler is simply a valve that diverts heat to either your radiators or your hot water. The diverter will normally be positioned to heat your radiators, but when you turn on a shower or hot water tap, the diverter switches to heat you water. 

If a diverter valve malfunctions, you will likely still have either heating or hot water, but not both. In most cases, the diverter valve will break and stop providing hot water, whilst your central heating will continue to work normally.

An boiler engineer will be required to replace the broken diverter valve. Find out how much it costs with our Quick Price Checker.

Is no hot water an emergency?

Hot water has become an essential part of modern life. From washing up dishes to showering, we rely on steady and reliable hot water supply several times throughout the day.

There are many factors that can result in no or reduced hot water in your property. Different boiler problems cost differing amounts to repair, and in some cases you may even be able to carry out a straightforward repair yourself. 

The first step in rectifying your hot water is to determine the problem. You can take a look at our list of troubleshooting tips above, or call in an expert to quickly repair your boiler.

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