A Guide to Cast Iron Radiators

A Guide to Cast Iron Radiators

Welcome to Trade Radiator’s Complete Guide to Cast Iron Radiators.

This special article is going to be your one and only resource when looking at anything and everything to do with cast iron radiators. We have developed this guide over some time to create one place where all the questions from you, our customers, are answered when you want to know the specifics about cast iron radiators.

We’ll be looking at how cast iron radiators are made in this day and age, why after all these years customers still love to them in homes across the country, how you can buy the right cast iron radiator for any space, and what you need to know if this is your first time looking at these delightful radiators.

It doesn’t matter if this is all new to you and you don’t know a plug cap from a robe hook; let Trade Radiators be your usher through the wonderful world of cast iron. Hopefully, you’ll pick up a trick or two along the way.

And remember that this guide, like everything in the complete guide series, we’ve condensed, and broken information into three parts; what cast iron radiators are, how to buy a cast iron radiator, and advice on using cast iron radiators.

So let’s take a look and cast an eye over this exciting area of radiator discussion.

Part 1: What are Cast Iron Radiators?

Understanding the Basics

For most people, when they see a cast iron radiator installed somewhere, or just happen to be browsing a site like Trade Radiators and come across cast iron products, their interest is piqued into learning more about cast iron radiators. The old school, rustic looking radiators have much more character than standard, flat panel radiators you’ll see in most rooms across the UK, and yet they’re just not as ubiquitous.

There are a few reasons for this, and we want to start by helping you understand what cast iron radiators are, what they look like, how to know if you have a genuine cast iron radiator installed, where they can be used, and many other common questions we get asked a lot.

Even if you’re not here for a comprehensive look at all things cast iron, you’ll be sure to find at least a few nuggets of information on why they make for excellent radiators before we move onto the buying guide.

What is a Cast Iron Radiator?

A gold cast iron radiator

A cast iron radiator is a radiator made up of sections. Each section is a casted piece (hence the name) of iron which is formed to a specific design. The sections are slotted or welded together using radiator gaskets or radiator nipples as connectors.

What Does a Cast Iron Radiator Look Like?

While techniques in recent years are seeing designers take a more modern approach with shapes and designs, a traditional cast iron radiator will look like a sectioned radiator with gaps between each vertical column.

It is essential to know that when talking about how many columns a cast iron radiator has, we are not talking about the number of sections that make up the radiator, but the number of vertical gaps running through each section.

For example, this radiator has two columns when looking at it from the side, making it a two-column cast iron radiator.

Conversely, this radiator has five gaps between columns, making it a six-column radiator.

You can have cast iron radiators with just one column to look more modern, like these Claredon cast iron radiators, but traditionally you’d be looking at two columns or more, as you can to give yourself as much space as possible to draw in cold air.

How do I Know if I Have Cast Iron Radiators at Home?

Let’s say you’ve just moved into a lovely home and noticed that some of the radiators appear to be cast iron. Chances are they will be, and that they’ll work fine in traditional home heating (i.e. hot water boiler) systems.

In the rarest of cases, especially in the UK, you may come across cast iron radiators which use steam instead of hot water. You would be able to tell if your system is using steam because the boiler is a steam boiler. Again, you wouldn’t usually see this in homes, but when you’re looking at large older buildings which all have very old radiators, there may be a minute possibility that a steam boiler is in use.

How are Cast Iron Radiators Made?


Cast iron radiators are made by heating iron and pressing/casting it into a mould under pressure, which helps form its shape. It’s then left to cool down so it can take shape properly. Remember that the radiator isn’t one big sheet, like a single panel convector radiator in your home would be, but is made up of identical sections.

These sections are bound together, usually with bolts (and sometimes welded) to create one solid radiator unit.

Are Cast Iron Radiators More Expensive?

Because of the process involved, it takes a little more time and expertise than most modern radiators to get to the finished product.

With so many different cast iron radiators having unique designs on the sections, you also need to factor in fettling (that’s where rough edges and corner get sanded down), hand polishing, assembly and pressure testing the product before it’s ready to be sold.

How Much Do Cast Iron Radiators Cost?

The price will depend mainly on size. Looking at the lower end of the scale, a small cast iron radiator would be around the £100 mark. Radiators in the 600mm range would be anywhere from £200 up, and this depends entirely on the make and model.

Do Cast Iron Radiators Have Special Fluid Inside?

Unless you’re adding an inhibitor to your radiators, a cast iron radiator will use the water that runs through the traditional heating system.

Radiators don’t rust on the inside unless they’re left prone to oxidation over the years. Whenever you get the likes of black water coming out while bleeding your radiators, or have cold spots in a radiator, there has likely been corrosion somewhere in your radiator.

Even if you notice it in a cast iron radiator, it won’t necessarily mean that’s where the rusty corrosion is occurring, as it could be getting trapped there.

Can Cast Iron Radiators Rust on the Outside?

When most people are shopping cast iron radiators for the first time, a common question is how can a radiator like this even work when the iron is exposed to the air? The truth is, cast iron radiators are not bare radiators.

Most, as standard, will have a protective layer or primer on top, so when you’re buying a cast iron radiator in a specific colour like silver, bronze, or gold, that radiator has already been painted.

It is quite popular nowadays to have what looks like a completely bare cast iron radiator installed. When you see a radiator which appears as such, it will have a polish/lacquer applied all over. This is done to help prevent moisture and oxygen clinging to the surface of the radiator and doing their worst.

Rust is the worst enemy of a poorly prepped radiator, and we’ll be discussing how to take care of rusty spots on a cast iron radiator when we get to the advice section of this guide.

Are Cast Iron Radiators Better than Steel Radiators?

If you didn’t know, most radiators are made from steel or stainless steel (a few are made from aluminium, but that’s a topic for another guide). The argument often thrown up is that cast iron is better than steel, and while it could be viewed as a case of each to their own, there are some ways in which cast iron might prove better for you.

Firstly, cast iron is a better heat conductor and retainer than steel, so when your heating turns off, you’ll know that a cast iron radiator can maintain a high temperature for longer. This lets you get away with needing a smaller sized radiator in comparison, as it can match the BTU of your space.

Secondly, if you have a cast iron radiator with more columns, you’re creating a larger surface area to work with, which gives you a better chance of a room getting warm quickly.

Thirdly, if you take excellent care of a cast iron radiator, it can last well beyond its expected shelf-life. While most of the cast iron range at Trade Radiators has a 10-year guarantee in place, a well-looked-after model can run flawlessly for years beyond that.

Part 2: Cast Iron Radiator Buying Guide

How to Know which Cast Iron Radiator You Need

Switching from a regular radiator to cast iron radiator can seem like a big deal if you overthink everything, which is precisely what we’ll try to prevent in this section of the guide.

This part is the Cast Iron Radiator Buying Guide, helping anyone with even so much as an inkling that they might like cast iron radiators become informed at what to look out for (and what to avoid).

If it’s your first time buying cast iron radiators, no need to worry at all, as we have all bases covered. Some of the factors we’ll be looking at include:

  • Size
  • Shape
  • Colour
  • Design Features
  • Functionality
  • Brand
  • Price
  • Accessories

Breaking each of these down is the easiest way to help you understand what type of product to get, and where cast iron works best for your environment.

As with any kind of radiator, the first thing we need to look at when buying one is what size to go for.

Choose Cast Iron Radiator Sizes

We mentioned this briefly in section one, but if you’ve jumped ahead to here, it is important to know that cast iron radiators are more efficient heat users. Because of this, they will hold heat and take longer to cool down when your heating is turned off. It tends to be the case from this that you can downgrade the size of your radiator when switching from standard to cast iron.

It isn’t so much the case of going from a 1000mm by 1000mm radiator to a 500mm by 500mm, but with improved BTU output at smaller sizes, when you’re working with cramped rooms like an ensuite or smaller living room, a switch to cast iron might work in your favour in saving valuable space.

As always, if you’ve no clue what the BTU output of your current radiators are, there is nothing to worry about as we can help. If you’d like an accurate idea of BTU a room needs to find a matching cast iron product, use the Trade Radiators heating calculator to suss it out. If you figure out the BTU and compare that to that radiator already in the room, you might even be surprised to learn your existing radiator could be the wrong size and wasting energy.

View All Our Radiators by Size

Figuring Out Cast Iron Radiator Shapes

A cast iron radiator

One of the best things about cast iron radiators is that they have a distinctive and impressionable shape. Even if you were to shop for a budget option, there’s no denying a newly installed cast iron radiator is going to look the part.

With the history involved and the fact that most brands didn’t share techniques and styles back in the day, there isn’t a uniform set of naming conventions for cast iron radiator shapes. Most brands will give their radiators unique names even if another brand has an identical looking radiator.

The less ornate and more minimal you make your design, the cheaper the cast iron radiator should be. We’ll touch on that some more when we get to Design Features in just a bit.

The Ideal Colour / Finish for Cast Iron Radiators

Cast Iron Radiator

When looking online, you should be thinking of a cast-iron radiator as a blank canvas, because they can take pretty much any colour or finish you like.

They type of finish you can get will depend on the make and model, but the manufacturer can sometimes lean towards a specific finish if they feel it works best. Some of the most popular finishes we have available at Trade Radiators include:

  • Grey & Anthracite
  • Black
  • Brass
  • Copper
  • Nickel
  • Silver
  • White

When it comes to colour, you’re spoiled for choice really at Trade Radiators. The majority of cast iron radiators will have the option of a custom colour match, so you can get a radiator painted any colour you like.


It’s often advisable to get this done professionally, rather than go it alone, as you could run into problems using the wrong type of paint (which causes bubbling, chips and splits) and not having even coverage throughout the radiator. Custom finishes, in everything from black and green to neon pink, are becoming a trendy option for customers in the retail and social sphere.

And if you’re wondering how to get a cast iron radiator with that rough around the edges finish of raw metal, you’d be looking for a raw/lacquered metal polish finish. This is where protective polish is applied to prolong the outside of the radiator from the risk of rust.

Design Features

With cast iron made with hot iron being placed and moulded in large casts, designers are sometimes hoping to leave a lasting impression on each section of the radiator. It could be that the creator is following a traditional design from radiators of years gone by, or they are using their artistic license to create a unique looking design on the panel.

While the casting process helps get those features in place, it is after the section has cooled that a radiator can come into its own. There are two processes carried out to help bring attention to detail. The first is fettling. Fettling in when edges and corners are trimmed or sanded away to help give each section a rounded top with no odd angles at play. It is a process which requires a reasonable degree of skill, or else you’d be left with oddly sized sections in your radiator.

The second part is known as hard burnishing (some people call it highlighting). It is where the designer will intentionally polish/brush down in and around the design they’ve created to help it stand out. The casting process can help put a design in place, but can’t go into greater detail, which is why having someone use a sanding tool to polish ad carve around the design before applying a finish helps add definition.

With this needing done section by section before the radiator is assembled, the craft involved is also another reason why cast iron radiators tend to be more expensive.

Cast Iron Radiator Functionality

Looks aren’t everything. Radiator functionality is so important and sometimes overlooked because it’s all too easy to fixate on having a pretty radiator over anything else.

With cast iron radiators in a field of their own, some of the key functional considerations to have would include:

  • Heat output.
  • Radiator location (remember that you can go smaller with cast iron).
  • How often you’ll need the radiator on.
  • What the ideal room temperature is.
  • If you want the radiator to act independently.

Electric Cast Iron Radiators

That last point is significant. A lot of people are put off buying cast iron radiators because they think it will always need plumbing into the central heating to work. With more and more homes looking to go fully electric, manufacturers are adapting with the times, and that’s why you’ll easily be able to get your hands on some fantastic cast iron electric radiators.

These radiators can be used on their own, and don’t need to rely on the rest of your system to work. Simply plug them in and they’ll to get warming up a room in no time at all. It has become quite a good solution for people who are adding extensions to their homes, or those working in commercial premises like salons and cafes who want a funky cast iron radiator but don’t want to start ripping the floor up for pipework.

View All Our Cast Iron Electric Radiators

Cast Iron Radiator Brands

Reliable cast iron radiator brands are few and far between. There are only a few who offer products at a reasonable price, and they include:


The majority of cast iron radiator products available on site come from Paladin, and there’s a good reason for it; they’re arguably the best in the business at creating high-quality cast iron products.

Built in the UK, every single one of their products is made with attention to detail and come with at least a 10-year guarantee it will work effortlessly.

Some of the most popular cast iron ranges made by Paladin include:

  • Clarendon
  • Neo-Georgian
  • Pimlico
  • Montpelier
  • Shaftsbury
  • Sloane
  • Victorian

You can shop for Paladin products here.


Now, West doesn’t make cast iron radiators, but they do help any installation look the part by providing radiator valves in matching finishes to many the radiator finishes mentioned earlier in this section.

We recommend taking the time to find a matching radiator valve for a cast iron radiator, as getting a lovely new radiator installed and only realising you have white plastic cap valves at hand, doesn’t leave things looking as pretty as you’d hoped.

You can shop for West products here.

View All Our West Radiator Valves

Tools & Cast Iron Radiator Accessories

Cast iron radiators need to capture a mood when they’re installed, and having the right tools and accessories at hand is the only way to ensure correct installation.

Cast iron radiator accessories you will want to consider include:

  • Reducers
  • Air Vents
  • Smart Controls
  • Pipe sleeves


The cast iron radiators we have in stock are made to fit with 15mm connections, which is what you’ll find in most UK homes when looking at pipework.

In some cases, especially when we’re replacing a very old radiator with a new one, it is important to check that your pipes match that standard size.

In older homes, you may see that micropipes were used, so if you have noticeably smaller or larger pipes, make sure you have reducers and adaptors handy to establish the connection correctly.

View All Our Reducers

Air Vents

Imagine a world where you never had to bleed another radiator in your life? Well, it’s a reality when you get air vents installed. For cast iron radiators, there are two products we recommend:

View All Our Air Vents

Smart Controls

Just because cast iron radiators use traditional design, it doesn’t mean they need to use old school controls. We have smart controls in stock to help you take control of heating in every room.

With many linked to your home Wi-Fi, the novelty of being able to knock on a cast iron radiator in the living room on the way home never gets old.

View All Our Smart Heating Controls

Pipe Sleeves

Pipe sleeves are the finishing touch that helps a radiator installation look complete. Get sleeves that have a similar finish to your new radiator, and it will look the part in no time at all.

Take a look at all our radiator accessories, including pipe sleeves, here.

View All Our Pipe Sleeves

Buying Cast Iron Radiators with Trade Radiators

With so many different features, shapes, and sizes, it’s all too easy to feel overwhelmed when buying a cast iron radiator for the first time. If this has become the case for you, then there’s no need to worry as Trade Radiators is your one-stop shop for buying new cast iron radiators.

As the UK’s leading and most trusted online radiator store (you can read genuine customer reviews here), anyone buying a cast iron radiator can be assured of:

  • Quick delivery
  • FREE delivery
  • Financing on most products
  • Top-Rated Customer Service
  • Unbeatable Prices

We aim to get cast iron radiators primed, painted, packaged and out the door as quickly as possible. Some products which already have a finish can sometimes be shipped by next working day, but we average five working days for cast iron radiators with metallic paint or primer (undercoat) applied.

When looking at custom paint jobs and unique finishes that require time to get right, it can take up to 10 working days. When you order your products, we’ll send out an email with all the information you need relevant to your order.

As always, if there’s a specific question you have about cast iron radiators visit our contact page.

Part 3: Cast Iron Radiator Advice & How-To Guides

Cast iron radiators are incredibly adept at heating rooms. That doesn’t mean that everyone knows how to operate and maintain them from day one out of the box. Sometimes people are a little embarrassed to ask what they perceive to be “silly” questions about looking after and fixing cast iron radiators when we all know there’s no such thing as a stupid question.

In this section of the guide, we’ll be covering common maintenance and care questions regarding cast iron radiators, with a particular focus on:

  • How to fit a cast iron radiator
  • How to change a cast iron radiator
  • How to use a cast iron radiator
  • How to clean a cast iron radiator
  • What to do when a cast iron radiator leaks
  • The biggest mistake dual fuel users make
  • Common dual fuel problems

If there’s a particular issue you don’t think has been addressed from the points above, have a quick look to see if covered in our DIY & Troubleshooting section. Guests of the blog use it to get some very handy tips on looking after cast iron radiators, and practical videos on how to troubleshoot common problems.

How to Fit a Cast Iron Radiator

Cast iron radiators are heavy old things the bigger you get. While they have their own foot stands to keep them in place, it does help to have a cast iron radiator installed to the wall to avoid any accidents. You would do this with a wall stay, which most of the cast iron radiators we stock have in the box already.

This video explains how to get your cast iron radiator installed to a wall:


A few key points to consider if you are going to install to the wall:

  • Make sure you’re not drilling into any pipe or cables behind the wall.
  • Always measure first before installing.
  • You always want to clamp to the rear of the radiator, so it is secure (and it looks tidier than a front connection).
  • If you’re buying electric, try to avoid “hiding” the socket as you want to be able to turn the radiator on and off.
  • Cut your rod to length to keep the radiator close to the wall (you don’t want it hanging out).

How to Change a Cast Iron Radiator

Cast Iron radiators don’t need any unique work carried out if you’re going to be changing a regular radiator for one. With them being heavier, it helps to have someone else at hand if you find it tough to move. You don’t want to try and lift a heavy object and damage something, or yourself, in the process.

If you haven’t changed a radiator before, and don’t feel confident about the process, please get a professional to do so, as you don’t want any accidents occurring.

How to Use a Cast Iron Radiator

How you use your cast iron radiator will depend entirely on the make and model of valve used. You can find out everything you’d ever need to know about that by checking out The Complete Guide to Radiator Valves.

Most cast iron radiators come with manual cap valves as standard in the box.

How to Clean a Cast Iron Radiator

Cleaning a radiator

With many cast iron radiators having unique polishes and finishes, you might fear that cleaning one of these radiators the wrong way will result in scuff marks and paint/polish coming off.

If your cast iron radiator has a painted finish, wipe it down to remove dirt and dust, before wiping it gently with soapy water (it’s a good idea to put a towel underneath to catch water).

If your cast iron radiator has a polished finish, every few months you’ll want to dust it down and check around the connections and valve entries.  Use a polishing cloth to help keep the shine on the radiator. Don’t jump to using popular cleaners and polish, as they could rub badly on the finish. Only use if you need to and have checked that the product is safe to apply.

When you have a truly stubborn stain, lightly cleaning away with a toothbrush or very low-level scouring pad may help but do take care.

What to do when a Cast Iron Radiator Leaks

A leak from a cast iron radiator can be worrying, but it should be easily fixable. A leak can happen if valves have been closed too tight (with PTFE tape splitting), or there’s a problem somewhere inside the radiator.

Most leaks are down to valves not being closed properly. When they’re too loose or too tight, it’s easy for water to cause problems. You need to remember that hot water in a traditional heating system needs to flow from radiator to radiator, so doing things like shutting off the out valve or tightening the entry valve can give you a hard time.

When you have a leak, turn the heating off, let the radiator cool down, and have a thorough check of the valves to see if you can pinpoint where the leak is. If you notice water coming from the connection when it is loose, closing off the radiator and replacing the tape around the valve is a quick fix. Again, if you don’t know what to do, get professional help.

When the leak is clearly coming from the radiator sections and not around the valves, you have a more significant issue and should call for help.

The Biggest Mistake Cast Iron Radiator Owners Make

It is important to remember that radiators can’t just take paint as easily as a wall or piece of wood. With constant changes in temperature, some paints will expand and contract, which ends up causing the paint to crack and split.

If you can, let us know what colour you want your radiator to be, and we’ll professionally paint the radiator for you. Most of our cast iron radiators are made to order, so if you have the time to wait for a few days more, we’ll get it looking perfect.

If you already have radiator paint you’ve used and want to apply that same paint to a new cast iron radiator, make sure you choose to have a primer/undercoat, which will be black, applied to help protect the radiator. Even if you choose a polished or painted finish when ordering, your paint may not take well.

Common Cast Iron Radiator Problems

A cast iron radiator on the fritz can leave you scratching your head for solutions. Knowing the common problems, and the simple solutions, are things every owner of a cast iron radiator should know.

Here are some of the common problems and solutions you’ll want to know about:

Cast iron radiator will not heat up.Check radiator valves are open and that heating is being supplied to pipework coming in.
Cast iron radiator is incredibly hot.Adjust your valve accordingly. If it’s a manual valve, turn it as low as you can go without completely closing it. If it’s a TRV valve, turn it to 1 or 2 and see what difference it makes.
Cast iron radiator has cold spots.Bleed the radiator when heating is off and check again. If it remains cold, call a plumber to see if there is a dirt/sludge build-up inside.
Cast iron radiator is making noises when turned on.Trapped air, which heats under pressure, can cause clicking or banging noises. The radiator may need bleeding, or the whole system checked by a plumber.

Get Cast Iron Radiator Advice & Order Today with Trade Radiators

If you’re read everything and made it this far, you’ll be happy to know we’ve now reached the end of Trade Radiator’s Complete Guide to Cast Iron Radiators.

We hope that all your questions and concerns regarding cast iron radiators have been answered, and you’ll have no problem at all finding the ideal radiator for any space.

For anyone who still has a burning question they need answering, or there’s a specific cast iron product you want more information on, please do get in touch by visiting our contact page. We’re always glad to help customers find what they need.

If you’re still looking to read more about this area of radiators, some of the most visited posts on the Trade Radiators blog around this topic to check out include:

And remember, you can always find the best range of cast iron radiators online by visiting TradeRadiators.com.