Radiators and TRV’s Explained Re February 6, 2023

Radiators and TRV’s Explained

Cold radiators

The radiator is a household essential that often gets overlooked by many. In over 90 million homes across the UK, the radiator comes in many shapes, sizes, styles, and materials.

When we think of a stereotypical radiator, we often think of a metal box that is typically placed underneath our windows, that all come in one standard shape and style and all do the same thing. Well, this is where this blog comes into play.

This blog aims to discuss all the different types, materials, and styles of radiators available; and explain how important it is to choose the correct one for your home.

Types of radiators

The most common choice of radiators is typically a plumbed or electric radiator. 

Many either choose to have a direct replacement of their existing appliance or an extension of their current heating system.

Plumbed Radiator

A plumbed radiator is the more common type. It uses the hot water supplied directly from your boiler to heat your home. A plumbed radiator is usually controlled centrally as a part of your central heating system. 

Although simply replacing an old plumbed radiator with a new one is simple, adding an additional plumbed radiator to an existing system can be more difficult. Remember to take this into consideration when thinking about costs.

Electric Radiator

As the name suggests, an electric radiator is powered by your mains electricity. 

Electric radiators are easy to install and are an efficient heating solution. Being portable means that they can be used in any room in your home where a plug is available. Another beneficial factor about having an electric radiator is that they are eco-friendly, using electricity to create heat rather than hot water. 

However, they are not always the cheapest to run. It is estimated that running costs could be up to three and a half times more expensive than if you were to heat your home with a standard gas boiler. However, if you are using an electric radiator to heat only one room in your home at one time, this could be more cost-effective. 

Electric radiators are also available in a range of different sizes and styles, so there is an option to suit all homes.

Dual Fuel Radiator

Alternatively, you may opt for dual fuel heating which combines electric and plumbed power sources for maximum comfort in your home. 

The dual-fuel radiator is a practical choice as it features both the heating elements used for an electric radiator, but it is connected to your plumbed central heating at the same time. This means that the radiator can be heated either by the central heating system or electrically. For a bathroom, ensuite or cloakroom you will more than likely opt for a dual fuel towel rail, and for other rooms, in your home, you may opt for a dual fuel radiator.

Did you know that WarmZilla doesn’t just offer boiler installations? We also offer additional extras that can be purchased upon checkout, including radiators and thermostatic radiator valves. 

cat on radiator

Radiator material types

There are four main materials that radiators can be made of, which help determine the efficiency and performance of the radiators. Radiators are generally made from one of these four materials:

  • Cast Iron
  • Aluminium
  • Mild Steel
  • Stainless Steel

The material of your radiator is actually more important than you think. The material your appliance is constructed from can affect how quickly your radiator heats up and how long the heat is retained.

Cast Iron Radiators

The Cast iron radiator was the most popular choice before modern home insulation became available. Although it takes a little while longer to heat up than other materials, they retain this heat for a lot longer than others such as a steel or aluminium radiator.

Mild Steel Radiators

The Mild Steel radiators are probably the most commonly used in UK households. This material is dependable and efficient when it comes to heating your home. Steel radiators are often a preferred choice as they are hard-wearing and built to last a long time. They are also the more cost-effective option.

Aluminium Radiators

Aluminium is the fastest material to heat up. Aluminium radiators are known for their ability to heat a space quickly and efficiently. On the other hand, it also cools down just as fast as it heats up, meaning that it doesn’t retain heat for a long time. However, as a result of this, it can be argued that this in fact makes it the perfect radiator for achieving ideal ambient room temperature. 

Aluminium radiators are also very lightweight and easy to install, which your Gas Safe Engineer will appreciate!

Stainless Steel Radiators

Stainless steel radiators or towel radiators as many call them, are often the preferred choice for locations such as your bathroom, as they are designed to minimise the risk of rust. This is why they are typically used for towel rails. Stainless steel radiators are ideal for retaining heat once switched off.

Have you ever thought about giving your radiator a facelift? Why not have a look at radiator covers? Head over to our friends at bestheating.co.uk for some inspiration! 

Radiator styles

Now you know a little bit more about the types of materials that radiators can be made from, here’s some information on the different styles of radiators that are available. 

As mentioned, choosing the perfect radiator for your home is essential, so let’s discuss each style to help you choose the best radiator.  So what styles of radiators are available? 

Single & Double Panel Convector radiators

Convection radiators are designed to work slightly differently from your standard radiators. Using a range of internal and external components, a convector radiator transfers heat through a cycle of warm and cold air. The warm air from the convector radiator rises, heats the room to a certain temperature. This air eventually cools down and then recycled through the radiator to become warm air again.

Type 11 Convector Radiator

The most common type of convector radiator that is found in most UK homes, is the Type 11 Convector Radiator. In simple terms, this is a single panel convector radiator, usually made with steel, that fills with water to heat the room. 

In addition to being single panels, Type 11 convector radiators also feature a set of convector fins at the back that have been designed to increase the surface area and help to increase its heat output. The benefits of choosing a Type 11 Convector radiator is that they take up less space in your home as they protrude less than a double panel and can be fitted in narrow areas.

Type 21 & 22 Convector Radiator

These are double panel convector radiators. Type 21 has two panels, one facing the wall and the other facing outwards. Between these two panels are a set of convector fins. The panels themselves are hollow which allows for heat to be produced either via electric power or your central heating. With Type 21 Convector radiators, the fins are usually zig-zag shaped and line the inside of the radiator.

Type 21 Convector Radiator

Type 22 is very similar to a Type 21, however, rather than just one set of convector fins inside the radiator, there are two. Although a Type 22 Convector radiator is thicker than a Type 21, it also generates more heat.

Type 22 Convector Radiator

To reiterate, Type 21 and 22 Convector radiators are double panel convector radiators that have an additional panel that sits behind the other and they come in two variations – Type 21 (two panels & one set of fins) & Type 22 (two panels and two sets of fins).

Horizontal Radiators

A horizontal radiator is what we all know and identify as a normal radiator, fitted nicely underneath our windows. These tend to be the less expensive option when replacing an old radiator in your home.

Vertical Radiators

Vertical radiators are not as common as the standard horizontal radiator but are definitely becoming more fashionable and popular. Vertical radiators are what they say on the tin, they are taller than they are wide and are great for narrow wall spacing or rooms with limited space. They can also be seen as a decorative piece in your home.

How to choose the correct size radiator

As I’m sure you know by now, there are several factors to consider when choosing your new radiators. There is plenty of information online regarding radiator size; BTU calculators are out there to help you make the right decision when purchasing a new radiator, however, this section of the blog aims to explain how to figure out what size radiator is the best option for you, without having to worry too much about numbers. 

When choosing the best radiators for your, you may find yourself asking such questions as:

  • What is a BTU?
  • What size radiator do I need?
  • How do I calculate the radiator size for a room?

Well don’t worry, we’ve got your back. Here is some information that we hope will help.

What is a BTU?

A BTU stands for a British Thermal Unit. 

A BTU is a traditional unit of heat that helps to work out the amount of energy that is required to heat 1lb of water by 1-degree Fahrenheit. 

Many people prefer to use the more traditional Watt to calculate heat output. In this case, all you need to remember is that 1 Watt of energy equates to 3.41 BTU’s. Alternatively, if you have a BTU measurement and would like to find out the heat output of your radiator in Watts all you would need to do is divide the BTU’s by 3.41.

What size radiator do I need?

With this equation, you can figure out what size radiator you need for each room. As mentioned, there are plenty of online BTU calculators that can help figure this out for you if you want to go the easy way around this (we don’t blame you).

A BTU calculator will use the dimensions of a room, taking into consideration things such as double glazing, north-facing windows, or french doors, which could account for heat loss, it will give you a final BTU reading that you require for that room. 

This value does not represent the total BTU requirement for a specific radiator, but rather the total BTU’s required from the addition of all radiators within that room.

What radiator do I need in each room?

In order to get an accurate calculation of what BTU output you need for a room, step one is noting the measurements of the height, width, and length of the room, as well as the size of the window area (that the length by the width of a window in m2). 

Step two would be to make note of how many radiators you would like, to heat your desired room. More often than not, 1-2 radiators are enough to heat a room. The amount of BTU’s required per radiator will depend on how many radiators you choose to have in that room.  

The final step is to divide the total BTU requirement by the number of radiators, this will give you the average BTU required per radiator and help you choose the best radiator for your home.

Types of radiator valves

You’ll probably want radiator valves for any radiators in your home. Radiator valves help to control the output of your radiators in each room.

Each radiator fitted in your home should ideally have a pair of valves that act like taps. One of the valves controls the amount of hot water entering the radiator, and the other, which is called the lockshield valve, manages the heat output. 

A lockshield valve is usually covered with a plastic cap for protection. This valve will control the water flow that enters and exits the pipework. Your Gas Safe engineer will often perform something called ‘balancing your radiators’, to ensure an even distribution of water around your home.

Manual Radiator Valve

This is the most common type of valve, which, as the name suggests, you manually operate. You turn them either left or right which turns the heating up or down. Turning the valve adjusts the hot water flow through the radiator and therefore, how much heat is emitted. 

Although manual valves are the easiest to operate and are smaller than the typical thermostatic valve, they can become a pain when you have to remember to manually turn them off, especially when you have to get out of bed to turn them off.

Thermostatic Radiator Valves

A Thermostatic Radiator Valve, also known as a TRV, is a self-regulating valve, meaning it pretty much takes care of itself.

Once you choose the temperature you would like your radiator to reach, the valve uses wax or liquid to sense the room’s temperature and adjusts the water flow accordingly. This means that once your radiator has reached optimum temperature, the TRV valve will shut off to stop the radiator from getting hotter. This option is much more cost-effective for your home.

Smart Radiator Valves

If you are planning on getting a new boiler then you have probably heard of smart thermostats that control your central heating. If so, then you could have also heard of a smart radiator valve. A smart thermostat is connected to WiFi which enables you to control your heating via an app from a smart device. If the smart thermostat is compatible with smart TRVs, you can control each TRV in your home from your app from wherever you are in the world.

How much do radiator valves cost?

It is important to remember that when purchasing a new or replacement boiler at WarmZilla, you can also purchase thermostatic radiator valves to save you money on your monthly heating bill and get that room temperature to the sweet spot. Here is a breakdown of how much each radiator valve will cost you on average.

Valve TypeAverage Cost 
Manual £5 – £35
Thermostatic£5 – £120
Smart £50 – £200 + (excluding the cost of the smart thermostat)

You will also need to consider the cost of installation. You will need a professional Gas Safe Engineer or plumber to fit your radiator and valves. 

The cost of this labour will vary but generally, you are looking at just under half a day’s work for one radiator with a full day needed for a complete system including around 10 radiators. On average costs could range from £100 – £350 but you’ll need to compare at least 2 quotes to make sure you’re getting the best deal. When getting a new boiler fitted by WarmZilla, you can add radiators to your order and get them fitted at the same time.

Common radiator fault

One of the most common radiator faults is caused by something called ‘sludge’, which can cause your radiator to be cold at the bottom.

You may be wondering how sludge has made its way into your heating system, well don’t panic, it’s a fairly common occurrence.

Sludge build-up

Sludge is the affectionate name given by heating engineers to the build-up of metallic elements mixing with dirty system water. It’s formed from the inside of your heating system (pipes and radiators) rusting over time, as water is pumped through your system it gathers up the rust and settles at the bottom of radiators. 

This gathering of sludge is what stops your radiator from getting hot as the water can’t evenly distribute itself around your radiator.

Limescale build-up

Another contributor to sludge in your system is limescale, particularly if you live in a hard water area. The minerals present in hard water can solidify and become limescale. Limescale mixes with the rust and sludgy water to create an ungodly mixture sent straight from the depths of hell to ruin your heating system.

If you’re suffering from a cold radiator, give our blog explaining how to fix this a read. 

However, if you buy a new or replacement boiler from WarmZilla, a system flush will be performed before installation, which could prevent the cause of ‘sludge’. If you are interested in the different system flushes available to help solve the issues caused by ‘sludge’.

Unbalanced radiators

Are some of your radiators heating up and others staying cold? If so, this might be a result of unbalanced radiators. Don’t panic, this is a fairly common fault and is something that you could fix yourself. 

When your radiators are unbalanced, you’re warmest radiators are stealing all the heat from the other radiators around your home. This means that you could be feeling like you’re on a summer holiday in one room and then like you’re in the Antarctic in another.  But how does this happen?

An unbalance in your radiators is caused by your boilers water flow. It occurs when hot water isn’t being distributed evenly throughout your home’s central heating. Here is a few steps you can do to fix this:

  • Bleed your radiators
    The first thing you can do is to inspect all the radiators in your home for cold spots. If you notice any cold spots, make sure you bleed them. For more information on how to bleed radiators, click here. 
  • Turn off your central heating
    It is important to turn off all your central heating once you’ve bled your radiators. This gives your radiators a chance to cool down ready for you to open your radiator valves. 
  • Open your radiator valves
    By now, you all should know what a radiator valve is and what they look like. Your radiator valve will be at the side of your radiator. You should open the valve by turning them anti-clockwise (about a quarter turn) until you are unable to twist them anymore. 
  • Locate the warmest radiators
    Now, turn your central heating back on and search for the warmest radiators in your home. Whilst you turn your central heating on, make sure you keep a note of which radiators are heating up and those that are not. This will help you to identify which ones are the issue. 
  • Restart your central heating one more time
    Yes, we know, it can be tedious. Like the last time, wait until all the radiators cool down and then boot it up one more time. 
  • Turn the lockshield valve on the hottest radiator
    Head over to the warmest radiators that are absorbing all of the heat from the other radiators. Make sure the valves are tightly locked, then turn them anti-clockwise by a quarter turn to open them.
  • Now you’re all done. 
    Once you’ve completed these steps, your flow rate should now be balanced, ensure that your hot water is diverting hot water to your radiators evenly.

If you are still experiencing issues once completing these steps, contact your local Gas Safe Engineer to come and have a look.

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