There is no such system that is considered the standard central heating system. 

Each of the projects requires different types of demand, and that needs to be fulfilled by meeting up all the requirements from several aspects. The most common type of boiler you will see on a central heating system in the UK is the combi boiler. Check out the best combi boilers here if you are considering replacing your central heating.

For this, you may need a well-controlled and advanced programmed central heating system which will be able to constantly monitor the system and adjust it according to the environment and its internal optimisation.

There are also some differences between central heating and local heating.

In central heating, the heat generates in one place such as a mechanical room in a large building or the allocated boiler room in a house.

The most common method is the combustion of fossil fuel to generate heat in a gas boiler for your home.

After that, the resultant heat starts getting distributed, typically forced by air through ductwork, steam fed through pipes, or water circulating through pipes.


How to drain a central heating system?

There are 6 easy-to-follow steps when draining a central heating system – professionals recommend:

Turn the boiler off.

As a precaution, we suggest that you turn off your boiler before taking any action. This will reduce the possibility of any unintentional injury by allowing the potentially hot water to cool significantly.

The water intake valve should be closed.

As you work diligently to drain the central heating system, you may ensure that no water enters the system by closing the water intake valve.

Find the drain-off valve and place a bucket underneath it or attach a hosepipe to it.

The drain-off valve for your central heating system must be found. After doing so, attach a hosepipe to it. Use a jubilee clip to tighten your hose pipe’s fit around the drain-off valve if you discover it is slack. This will prevent it from coming loose and contaminating your floor with unclean water.

Put a bucket beneath the drain-off valve if you don’t have a hosepipe. After it is filled with water, briefly turn off the valve, empty the bucket, and then repeat the procedure.

Pump out the radiators

First, make sure that all of the radiator valves on the property are open. After that, go back to the drain-off valve where you hooked the hose or set the bucket, and turn it on. The water in your central heating system will start to drain.

To quicken the procedure, open the bleed valves.

Open the bleed valves on your radiators to quickly drain the water out. When you do this, you will audibly hear air being drawn into the system. To prevent water from spilling, don’t forget to arrange containers beneath the radiators.

Finish the draining procedure

Close the bleed valves back up once you are certain that all the liquid has been released from the system and there is no longer any water filling your bucket or flowing out of the hose line.

Once every valve has been shut, go back to the drain-off valve with the hose tubing attached and shut it as well. There could still be some water in the hose when you remove it, so take caution.

There are several different types of central heating systems. 

There are many different types of central heating systems, such as:

Connected to Gas central heating Boiler, Electric central heating Boiler, Condensing Boiler/ Combi Boiler, Regular Boiler, System Boiler and Geothermal heat pump and air to water the heat pump.


Here are the Key features of Central heating 

  • It doesn’t require any forced air movement, no hot and cold spots, no draughts, or noisy fans to contend with. The heat comes out unobtrusive and passive way. It warms both fabrics and objects within the room.
  • Heated water is pumped out from the hot water cylinder via underfloor pipes or into the radiators. It then releases the heat gently into the room.
  • In New Zealand, diesel-fired, and natural gas boilers are the most commonly used systems by people. Many models can also produce on-demand hot water for domestic tap use. Some of them also heat wet systems such as a spa or swimming pool at the same time supplying domestic hot water and a central heating system. To know further, you will need to gather a rough idea about the boilers.
  • The overall process is immensely good and efficient. There will be no water consumed, and when the water arises to the temperature, then it gets switched off. At the same time heat continues emitting from the radiators or the pipe.
  •  Every system is fitted with a time controller or a thermostat which allows warmth to deliver only when it is required. Additionally, individual radiators can also be used to fit with the thermostat allowing you superb control over the heating supplied in different parts of the house.
  • Central heating systems are quite easy to maintain, and draining a heating system with a boiler can be done with a bit of information from the Internet and some tools yourself if you feel confident enough.

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The central heating system utilises underfloor pipes and can be installed in a renovation or new home to deliver heat on demand before the floor slab becomes laid.

A well-mounted radiator utilised in a system can use and install in existing homes or new homes.

The radiator requires a high temperature, which can be achieved by any central heating system.

If you need a new boiler central or heating system, please fill in our contact form, and somebody will contact you as soon as possible to advise you on the best system to suit your needs.


What type of central heating do I have?

When attempting to decide which of these you presently have installed and which you should get in the future, it’s simple to become confused because there are just a few primary types of home heating systems available. How your house is heated and the expense of doing so can be significantly impacted by the water system you choose and the boiler that is most suited to supply the hot water it needs. Even though the variations might not be immediately noticeable, it’s simple to recognise your system by looking at a few important components and where they are located in your home.

The types of central heating systems you probably have are:

  • Conventional Central Heating – Two high-up water tanks are needed for this system, and a boiler is used to heat the water before it is stored in a hot water cylinder.
  • Combi Boiler Heating Systems – There is no need for a water storage tank elsewhere in the home because they run on pressurised water from the main supply.
  • Sealed System Heating -Both sealed (or vented) systems employ a hot water cylinder to store water until it is required by showers and faucets, and they both call for a hot water supply tank high in your home, often found in the loft.

What temperature should my boiler be set for central heating?

Set your boiler to at least 65°C if you want a decent combination of comfort and effectiveness. It won’t harm to increase the temperature a little. However, it’s crucial to not lower it than that. This prevents germs from growing in the water.

Boiler installation costs

Installing a traditional boiler will usually cost around £1,500 to £1,800 for the boiler and the install, and slightly more for a combi boiler – up to £2,000.

For a full breakdown of boiler installation costs, take a look at our dedicated boiler installation costs guide – new boiler costs.

The overall cost of the boiler may come down if included as part of a full central heating refit.


Radiator installation costs

The total price of radiators can vary depending on the style you buy, with typical prices ranging from around £150 to £250.

If you were replacing a single radiator individually you would also need to calculate in a larger cost for the installation, which would also include bleeding the system – heating engineers will typically charge around £300 a day for a two-man team, but when doing a full system installation, the job will usually be priced as a single cost rather than worked out on a day rate or by the hour.

When doing an entire installation, with several new radiators, it can bring the price down – we would expect the price for new radiators for a three bedroom home to be around £1,000 to £1,200.


Water tank installation costs

Depending on your choice of boiler, you may need a water tank to be installed to supply the system.

This is typically one of the cheaper parts of the process, costing around £200.


Electric central heating installation prices

Electric heating is another option for properties without access to the mains gas network.
You can go for night storage heaters, which store electricity obtained at night-time when prices are cheaper . The stored heat is then used to heat the property throughout the day.
An Electric boiler central heating is also available but bear in mind electric is the most expensive way to heat your home.
Modern storage heaters now come with thermostats and features such as remote wi-fi controls and programmable timers.
You can also buy high heat-retention storage heaters, which are designed to be more efficient than previous kinds.
  Central heating installation cost calculator
When calculating your central heating installation costs, there are several factors that you need to consider.
The most important is the size of the house and the number of rooms.
This will affect the size and capacity of the boiler.
You will also need to take into account the boiler brand and make, as that will also have an impact on the price.
You will also need more radiators for a larger number of rooms. In fact, you may need more than one radiator in very large rooms. The more radiators you buy and install, the more you would need to pay.
Finally, you will also need to install pipework for heat distribution.
You’ll need less pipework for a smaller property

 you’ll pay less in central heating installation costs for a smaller house.

you should get quotes from at least three different companies.

This way, you’d be able to get competitive prices along with the service you need.


Central heating running costs per hour for different boiler types

The cost of your central heating can vary depending on the fuel source that you use, as costs can go up and down. Some of the popular sources that can be used for central heating include mains gas, LPG, oil and electricity, which all have different methods of powering your heating system and at a cost difference.


Using an appliance in your home will lead to energy consumption, which will influence the running cost of your heating. This includes things such as cooking, electricity, radiators and many other home appliances.

Typically, the unit to measure the output in kilowatts (kW) and per kilowatt-hours (kWh), which can both be used to help you figure out energy costs for each type of fuel based on their average power usage.

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The A – Z Guide Of Central Heating Systems 2022

Central Heating Systems
Central Heating Systems

When it comes to understanding your central heating system, and all the different components, it may look confusing but is very simple really.

We have prepared this simple guide.

Generally speaking, when it comes to boilers there are only three main types of boiler available, and these are the ones typically found in your home

Conventional Boiler

If you have an older home, or have not updated your boiler for a while there is a good chance you’ll have a conventional boiler.

These also go by the names heat only boiler and regular boiler. The standard boilers can be identified primarily by the fact that you have a water tank for the boiler in your loft and a hot water tank in your airing cupboard. Because you need so much space to accommodate these central heating systems, they are more suitable for larger homes.

These boilers use gravity to feed water through to the boiler, which is why the water tank is usually found in the loft of a house. A separate hot water storage tank is used to hold hot water. The type of water cylinder used in a conventional heating system is called a vented cylinder, or an open vented system.

Because water needs to be heated in these systems in advance of use this can take quite a long time. This typically means you should set your heating controls up to provide you hot water when you are most likely to use it, such as in the morning before work, and for when you return in the evenings. Often, older versions of this boiler type are the least energy efficient so your energy bills are likely to be quite high when compared to other boiler types. This type of set up has a vent pipe that connects the cold-water storage tank in the loft to the hot water cylinder.

Explore  range of conventional heat only boilers at Mr Central Heating


System Boilers

When it comes to system boilers the main difference with these boilers is that they do not have a cold-water storage tank in the loft. However, they will still use a storage cylinder to hold the hot water in the heating system. This type of boiler draws water direct from the water mains to supply the system with water. This means that if there is very low water pressure from the mains supply, then these boiler-types may not be suitable for your requirements.

System boilers use unvented cylinders in their set up and the system itself is sealed. This helps to increase the water supply pressure in the system. An additional piece of kit, called an expansion tank is used to ensure that when the water in the system heats up, the excess water has a place to go (into the expansion vessel). Water expands when it is heated, so therefore the expansion tank is required.

One of the main benefits of a system boiler over a conventional boiler is that since they do not require a cold-water storage tank in the loft, less space is required for the boiler installation. The downside is that they do require more regular maintenance and installation costs are a little higher than a combi boiler. Another thing we’ve already touched on is that the mains water pressure is needed for a system boiler to work. If your home has very low pressure then a system boiler might not be the right boiler for you.

Explore our range of system boilers at Mr Central Heating

Our Recommendations
Ideal Vogue Max 32
Baxi Megaflo 32
Vokera Easi-Heat Plus 30S


Combi Boilers

The combi boiler (or combination boiler) is a popular type of boiler found in many modern homes and especially flats where space is at a premium. Combi boilers combine both the hot water heating requirements, but also the central heating too. These boilers also use mains water pressure to operate instead of a tank in the loft. If the mains pressure is very low in your home this type of boiler may not be suitable.

Some of the main benefits of a combi boiler is that they can heat hot water when it is required, since these boilers do not store hot water. So, you can have instant hot water when you need it. Another benefit is that this means that not only do these boilers not need a cold-water tank in the loft, but they do not need a hot water cylinder either. This not only saves space, but also on cost and adds a lever of simplicity to the overall installation. This means it should be cheaper for your heating engineer to install ensuring that the overall boiler cost is lower than other boiler types.

High output combi boilers are available too, meaning that the combi boiler is suitable for all types of dwellings. For example the Vaillant ecoTEC Plus 938 can deliver up to 20 litres of hot water per minute without the need for a separate hot water cylinder or loft water tank, making this boiler a great choice for a family home.

Explore our range of combi boilers at Mr Central Heating


Our Recommendations
Vokera Easi-Heat Plus 32C
Ideal Logic Plus 30
Vaillant Plus 832


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Condensing Boilers

Another phrase you might hear when you’re looking at a new boiler is the phrase ‘condensing boiler’. This isn’t a completely different boiler type, such as regular, system or combi boiler, but instead a mechanism that a boiler uses for better energy efficiency. So, if you’re wondering if you need to buy a combi boiler or a condensing boiler, the chances are, when it comes to modern boilers you’re probably talking about the same thing. This means that a brand new conventional, system or combi boiler that uses gas or oil for fuel will likely be a condensing boiler too.

Condensing boilers are a rated in terms of efficiency, which means they are better for your wallet and the environment. These are the most efficient boilers you can buy for the home. However, due to the laws in the UK since 2005 all new boilers that are installed need to be a condensing boiler type.

The way a condensing boiler works is by reusing the heat from waste gasses generated by the boiler. Waste gasses, instead of being released directly to the environment first go via two heat exchangers which convert the excess, waste heat into additional energy. A condensate pipe is connected from the boiler to the outside of the building. This plastic pipe is used to transfer waste water from the boiler to the external drains and sewer.

Another important factor for condensing boilers is that they only work with certain fuel sources, either gas or oil. Gas is quite a typical fuel supply in England, but oil boilers are less common and are typically only found in locations where there is no gas supply, such as in rural locations. Therefore, if you can only heat your home with electricity, then you cannot use a condensing boiler.

Hopefully you’ve picked up a good understanding of what the different types of boilers are and how boilers work from this guide. You can shop for a replacement boiler at Mr Central Heating. However, if you have further questions please do not hesitate to contact Mr Central Heating who can help you pick the correct boiler for your home. Speak to someone at a local Mr Central Heating Store today.

The installation of central heating systems  can be a costly and time-consuming process.

However, while it’s clearly important to hire a qualified gas heating engineer to fit the main gas line to your new boiler, it is possible to reduce costs by conducting the rest of the installation yourself.

If you are handy and have plumbing experience, we have prepared a step-by-step guide to installing central heating. We do recommend you leave the gas boiler installation to a Gas Safe plumber.


Is It Difficult To Install Central Heating Yourself?

Installing a new heating system requires a high level of skill and understanding.

This is due to the fact the vast majority of current home systems require connections to both gas and water mains while also utilising an interconnected network of hot and cold water pipes.

More to the point, the larger the task, the more complex it becomes. Difficulty also depends on the size of the project and how much of the existing pipework/system you plan to replace.

However, with sufficient experience and the correct equipment and support, installing your new central heating system is very achievable.

You just need to be prepared.


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What Will You Need To Install A Central Heating System?


A boiler

Clearly, when installing a new system, you need a central unit to provide your heat. This is a boiler. With that in mind, you’ll need to choose a boiler that is appropriate for your property’s needs. There are a number of boilers to choose from:

Conventional Boiler

The output of regular boilers varies depending on their size and requires the use of, and therefore storage to accommodate, a hot water cylinder/tank.

Combi Boiler

Combi boilers are, perhaps, the most popular type of boiler available today.

Here, the need for a hot water tank is removed as the combi heats water to demand directly from the mains water supply.


System Boiler

System boilers are slightly more environmentally-friendly than their conventional and combi boiler counterparts and thus, combined with lower long-term running costs, are becoming more and more popular.

That said, system boilers require a large amount of room in order to house both the body of the boiler and a large water tank. For this reason, they are best suited to larger properties with two or more bathrooms.


Biomass Boiler

Biomass boilers are the most expensive heating system on our list, with professional fitting costing between £10,000 – £14,000. That said, once installed, owners of biomass boilers qualify for the Renewable Heat Incentive, whereby they can earn a fixed fee in return for every kWh of renewable energy they yield.

Moreover, biomass boilers are cited as carbon neutral as the burning of the biomass fuel emits and absorbs carbon dioxide in equal measure.

Liquid Petroleum Gas Boiler

More often associated with off-grid properties, liquid petroleum gas boilers (LPGs) require the owner to source and store their own supply of gas.


Just as the type of boiler you choose will impact the complexity and price of installing your new central heating system, so will how many radiators you choose and their style and size.

In general terms, the larger and more elaborate your radiators, the greater their cost. With that in mind, it’s important to choose your radiators based on your budget as well as their aesthetics.

If you need radiator valves or accessories, simply click the links to view PlumbNation’s premium radiator parts.


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Control system

There are countless heating controls available today, and, broadly speaking, the more intelligent and intuitive your controls, the more efficiently your system will run.

Therein, installing thermostatic radiator valves in each room as part of a smart thermostat system will enable you to tweak and control the temperature of each room at will. These can cost between £125 – £200 for each room and may also require a subscription.

However, if you’re happy to utilise more traditional heating controls, this will reduce the cost and energy-efficiency of your heating but cost less in the short term.


We’ve discussed a few of the required parts of your new heating system. However, depending on the type of boiler you choose, you may need to source a variety of additional parts to maintain its condition and efficiency. These may include:

  • Filters
  • Thermostats
  • Cleaning solutions
  • Hot water pipes
  • And more.


Clearly, it’s important to acquire all the necessary tools required to install your new system before beginning installation.

As such, once you have purchased your new boiler, you should also receive guidance regarding what tools are needed.

However, if you remain unsure, please don’t hesitate to get in touch with the PlumbNation experts as we’re happy to provide advice and, indeed, the tools you need. To speak to us today, simply head over to our Contact Page.



Installing Central Heating: Step-by-Step Guide

So what does central heating installation involve?

Read on for our step-by-step guide, which details everything you need to know.


Step 1: Create a central heating map

The first step is to create a map of your new system.

Therein, locate your new boiler in a position that allows easy access to mains hot water and gas supplies while also providing direct ventilation to the roof. When placing your radiators, make sure they are positioned as close to your windows as possible, as one of their main functions is to combat heat loss (through the windows).

Once complete, purchase all the necessary parts.


Step 2: Install the radiators

Make sure to install your new radiators between 4 and 6 inches from the floor. This provides sufficient room for valve installation and maintenance.

Additionally, to enable full control over water flow, each radiator’s flow connection should be fitted with a wheel valve and, likewise, each return connection with a lockshield valve.

Step 3: Lay the pipes

Once you have installed all of your radiators, measure the amount of piping you need to connect them to your boiler and proceed to lay it. Cheaper plastic pipes are becoming more commonplace, but we recommend using copper piping with capillary or compression joints.

Ensure that your pipes can vent to the radiators, as this will reduce the risk of airlocks.

Step 4: Set up the control system

To install your new control system, simply follow the manufacturer’s instructions provided with the device.

Step 5: Fit the boiler

Next, turn the hot water and gas off and follow the provided instructions to fit your boiler. For the gas connection, you must use a gas safe registered engineer to mitigate the inherent risks that gas presents.

Step 6: Commission the system

Finally, it’s time to commission the system:

  1. Close the radiator vents
  2. Flood the new system with water
  3. Activate the heating pump and re-vent the system
  4. Turn the boiler on and use the lockshield valves to balance the volume of water in each radiator.

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Is it safe to install central heating myself?

Gas central heating installations carry an inherent risk due to their connection to a gas mains supply. As such, it’s important to utilise the services of a qualified gas heating engineer to ensure this element is fitted safely and securely.

Otherwise, with the proper knowledge and equipment, it is relatively safe to install your new system yourself.


How long does central heating installation take?

Installation can take anywhere between a few days to a few weeks depending on the size of the project and the ability of the installation team.


How much does central heating installation cost?

Central heating installation costs vary depending on the size of a project, the chosen system and the time it takes to complete. As such, we recommend shopping around to secure various quotes for your project before committing to having your boiler installed.


Where can I buy the parts for my central heating system?

Whether you’re installing underfloor heating, a new hot water storage tank or replacing your copper pipes, you can buy any parts you need through the PlumbNation store. We provide expert advice and thousands of premium parts at affordable prices.

So if you need a part, we’ve got you covered.


Guide to Heating Controls

Apart from the boiler itself the other aspect to a central heating system that relates directly to the radiators is the heating controls and thermostat.

Often, you’ll find a thermostat fitted to your central heating system (often from the manufacturer Honeywell). This is used to control the overall temperature of the home. Generally (traditionally at least) the thermostat was in just one place in the home, someone near the centre.

The user can adjust the temperature control on the thermostat to alter the overall temperate in the home itself. Older thermostats use an analogue dial mechanism and are very simple to use. Later models may be digital and slightly more complex to operate; however, they are still quite straight forward.

You can browse our comprehensive range of heating controls at Mr Central Heating

It is also possible to install a room thermostat to control the temperature in an individual room.

Thermostats control the heat output from the boiler itself and can switch the boiler on and off, whereas radiator valve control the heat output from the radiators. So, you can have a TRV fitted and a room thermostat together since they are complimentary.

The very latest technology available are smart thermostats such as those available from Nest. A smart thermostat is an intelligent device that can be connected to your phone or computer to help control your central heating. It can also integrate with other devices in your home to create a ‘smart home’. Smart Thermostats are great because they can learn your lifestyle patterns, such as when you are regularly out of the house at work etc.

They will control the central heating system automatically based on these learning patterns, which means they can save you a lot of money long term since they will switch off the heating when you are not around. If you want to save money on your heating bills and are interested in the very latest technology then smart thermostats are the way forward.


Radiators Cold At The Bottom? – Easy Fix When You Know How!

Now that winter is upon us, everyone is switching on their Central Heating and finding after a long sleep, their heating seems to be not heating the house properly.

This blog is all about :

  • Common Central Heating Problems
  • Grants For Free Central Heating
  • Grants For Free Boilers
  • Radiator Valves


Your Radiator Is Cold At The Bottom

A radiator cold at the bottom and hot at the top is usually down to the build-up of sludge in your central heating system. Sludge  is a black, mud-like substance which is a by-product of corrosion inside the heating system usually due to lack of inhibitor ( corrosion preventer)

This sludge would have been built up over many years and will be circulating around all your radiators with deposits sticking in some or all of your radiators.

Sludge does impact a radiator’s ability to heat your room so you do need to take action to fix it.

How Does Sludge Affect Radiators

Sludge being denser than water will sink to the bottom of the radiator.

This stops hot water moving through the radiator evenly and it will block the radiator eventually if not attended to.

Best Way To Remove Sludge

DIY  –  Disconnect the radiator and remove it from the wall, and then flush it out in the garden using a garden hose to the radiator.

If this does not work it may be better to replace the blocked radiator with a new one especially

It may also be wise to do this if the old radiator is showing signs of rust or corrosion on the outside. Replacing it before it develops a leak could save a lot of future headaches. After replacing the radiator, it’s important to add a chemical inhibitor to the system.

This will prevent the formation of sludge in the future.


Power Flush

Powerflush – a heating engineer will use a machine to powerfush water and anti-corrosion chemicals through your central heating system.

All sludge will be forced out  from all of your radiator.the engineer will connect a pump to the heating system which then pushes a chemical through the pipework and radiators at a high speed, thus breaking down and removing the sludge. After this process is complete the engineer will then use a descaler to remove limescale, and also a corrosion inhibitor which will prevent rust from forming again in the future.

Sometimes the most effective solution if the blockage is particularly stubborn is to bite the bullet and  replace the radiator.


Bad Blockages

If the blockage is very bad and the Powerflush is not enough, the engineer might also have to dislodge pieces of sludge using tools on the outside of your radiators.

This happens more frequently in hard water areas as there will be extra limescale which makes the blockage harder to remove.


Other reasons why radiators is cold at the bottom but hot at the top?

Assuming the radiator is free from sludge, It could be is that not enough hot water is flowing through it.

Hot water will naturally rise and could be that the little amount which is getting through is only enough to heat the top – and it probably won’t be very hot either, in comparison to the other radiators.

  • Check that both the  thermostatic radiator valve and  lockshield are open
  • The radiators may need balancing.


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Why Are My Radiators Cold?

There are several probable causes as to  why your radiators are not not getting hot.

These are the most common reasons for this and you should investigate all of them.

  • Radiators Are Blocked  – debris in the pipework or filter
  • Radiators Need Balancing    
  • Thermostatic Radiator Valve Stuck
  • Pump not working / has air in it
  • Air in the system
  • Lockshield  fully closed
  • Boiler or heat pump not working properly
  • Central heating has turned off

Radiator is Blocked

If your central heating system has not been serviced regularly, then there could be a build up of debris in the pipework or the filter.

This build up of limescale, sludge, rust or debris flowing through the system will eventually settle in your radiators creating a blockage.

Blockages that start off fairly small can quite quickly become large blockages and interrupt your central heating flow.

Blocked radiators are usually cold at the bottom and warm at the top due to insufficient flow.


Blocked Radiator Fix

 Remove the radiator and flush it out  thoroughly with a garden hose, before replacing it.

If you have several radiators not heating up then it may be necessary to have them power flushed by a professional.

A power flush uses pressure to shoot water and chemicals through the system, removing dirt and flushing it away down an outside drain.


Radiators Need Balancing.

How To Balance Radiators

  1. Turn off your heating
  2. Open all radiator valves
  3. Note the speed each radiator heats up
  4. Allow your heating to cool down
  5. Turn your heating back on
  6. Adjust the fastest radiator
  7. Repeat for other radiators.


A Thermostatic Radiator Valve is Stuck

If it is just one radiator not heating up, then a stuck thermostatic radiator valve could be the culprit.

A thermostatic radiator valve (TRV) controls the flow of hot water to a radiator and occasionally these do get stuck so not opening to allow the hot water in.

The TRV works by pushing a pin in and out and sometimes this pin will corrode and not move.

Try to free the pin using pliers and grease but don’t use excessive force as you might damage the pin and it can pop out or leak. Replacing the TRV is usually the best practice and will cost you around £12 to DIY.


 Pump is Not Working

If a few, or all, of your radiators are not heating up, the circulation pump could be to blame.

Circulating pumps move hot water around a heating system, taking it from the boiler through the pipes to your radiators and hot water cylinder in some cases — before taking it back to the boiler.

Sometimes, blockages or airlocks in the system will occur.

Good indicators that this may have happened, other than radiators not heating up, include a water leak from the pump, unusual noises coming from the pump, casing that is hot to touch and no hot water.

You can try bleeding the pump or exchanging it.


 Air in Heating System

A very common cause of radiators not heating up is an airlock in the central heating system.

“There could be air in the system which would mean that the radiator may only heat a little bit at the bottom, or not at all if there is a lot of air,

“You will need to bleed the radiator to get the air out.

“As you let air out of the system you need to allow more water in.

A gravity fed central heating circuit should fill automatically but a high pressure system will have a valve (or two) to let the water in.

Don’t leave this valve open. Pressurise the system a bit and then bleed the radiator. It is usually best if two people do this but if in doubt call in a professional.


 Lockshield Valve Closed Or Open Too Much

On the opposite side of the radiator to the TRV is a lockshield valve with a cap on it.

If this is closed no water will flow to the radiator.

If you open it too much (This is often only a quarter turn open ) the boiler water will now circulate more through the closed radiators and hardly ever get heat to furthest away radiators.

A good signal  will be if the radiators upstairs or those nearest to the boiler are getting hot but the downstairs radiators are cold.

The system will need to be rebalanced.


The Boiler is Not Working

An obvious reason for radiators not working is a faulty boiler.

Check your boiler  is on the right setting and appears to be working ok

A fault code will usually alert you to a problem.


 The Water Pressure Has Dropped

If you have a combi boiler, or a high-pressure central heating system, the problem could lie with a drop in pressure, causing the boiler to cut out.

Take a look at the pressure dial — it should be in the range specified in the instruction manual.

If not, you will need to top-up the water (check your manual for instructions) to repressurise the boiler.


The Central Heating is Off


Check that your central heating hasn’t been switched off or set to summer mode, or to heat the water only, by accident.

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How do Radiators Work?

Radiators work through a heat transfer process called convection.

When water in the radiator is heated, the surrounding air is also heated up via convection and this hot air is then moved around the room as the air circulates.

Radiators are normally connected to a central heating system via pipes and hot water flows through these pipes and into the radiators themselves transferring hot water into the radiator. As mentioned, this hot water heats the room via convection. The hot water doesn’t remain in the radiator, instead the hot water flows through the radiator and out again to the next radiator in the chain. As the hot water flows through the system it starts to cool down. When it flows back to the boiler the water is in a cooler state, and the boiler then reheats the water. The process repeats so long as the system is turned on.

As the radiators in the central heating system are connected in a chain, the radiator closest to the boiler is exposed to the water when it is at its hottest, whilst the radiator at the end of the chain, located just before the hot water returns to the boiler will be exposed to the coolest water. Because it is desirable to have all the radiators operating at the same heat output a process called balancing is used to ensure that the radiators all work to a similar temperature. Balancing works by restricting the flow of the water into a radiator. The balancing process is carried out by adjusting a valve called the ‘lockshield valve’. Either by restricting or opening the flow of water into the radiator.


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