Cast Iron Radiators – Benefits and Helpful Tips

Cast Iron Radiator Range
Cast Iron Radiator Range

Cast Iron Radiators are a luxury statement piece to any room whilst also providing a practical use with its added benefits. Cast Iron Radiators have been around for a long time, but they have been given a new lease of life in the past few years with a growth in popularity.

Key Benefits


Whilst cast iron radiators take longer to heat up, they retain the heat for much, reducing the pressure on your boiler to maintain the temperature in your room. They take up much less wall space than steel or aluminium for the same heat output also. This makes cast iron the ideal choice for homes with limited space.


With cast iron radiators, you can customise to fit any style or colour scheme. All our cast iron radiators are made to size, and over 50 models with various heights and styles available, you can create the perfect combination for your home, whether modern or traditional. The finish options open up your design choices, with the ability to finish in any RAL colour , colour match, genuine Farrow and Ball, Aged Finishes, or our Hand Polished finish.

You can speak with your local dealer to discuss all options available.


An increase in environmental awareness has made cast iron radiators even more popular than its steel counterparts with its increased efficiency. Due to steel radiators losing their heat quickly, it causes the boiler and heat pump to work harder.

Using thermostatic valves to set temperature per room will also provide significant energy savings.

Heat Sources

Cast Iron Radiators have excellent heat conductivity and density, which means they hold heat transferred from the ground much longer. This means that cast iron radiators are ideal for use with natural heat sources such as ground or air source heat pumps. As the water travels a circuit from the ground and around the building, when it reaches the cast iron radiator it will already have retained the heat from the previous circuit. The heat pump therefore doesn’t have to work as hard , which saves you money in the long run.

Installation Tips

Your cast iron radiators will be delivered on a pallet via kerbside delivery. Whilst the radiator is on the pallet it will be fully supported, and the gaskets will not be put under any undue stress. Cast iron radiators are VERY HEAVY so please ensure you have sufficient help to unload your order when it is delivered to you. It is important that the full length of the radiator is supported, and the product is carried upright at all times. A common cause of leakage is due to strain on the gasket seals caused by carrying the radiator flat without supporting the middle sections or dragging the radiator. The longer the radiator the greater the strain imposed on the watertight seals. Two strong pieces of wood can make good handles when inserted between the last 2 sections at either end.


Cast Iron Radiator Installation
Cast Iron Radiator Installation

Cast iron radiators are for use on closed heating systems only, they are not suitable for installation on secondary HWS circuits. Upon completion of the installation the entire system must be thoroughly cleaned and flushed to remove debris and flux residues etc. When a chemical cleanser is used it must be thoroughly flushed from the system. Arroll recommends the use of the Fernox brand for power flushing and rust inhibitor it is vital manufacturers guidelines are followed. After treatments, the water should be checked for a neutral PH between 7 – 8. Following this procedure, the system must be closed with a good eminence water treatment to prevent corrosion. System design, flushing and dosing must be in accordance with BS 5449, 1990, BS EN 12828:2003 and BS 7593.

The most common cause of leaks is over tightening of the valve tails into the bottom bushes of the radiator. Over tightening will crack the bush. When screwing the valve tail in to the bush turn it finger tight then using a spanner turn it until there is only moderate resistance. Using a 4” (100mm) spanner it is difficult to over tighten. It is easy to over tighten and crack the bush with an 8” spanner.

All Arroll radiators come with end bush’s hand tightened only.

This is to allow easy installation of valve tails. A thread sealant must be applied to the radiator end caps and to the valve tail threads to get a water tight seal. LSX sealant available at all plumbers’ merchants is recommended. PTFE tape is an acceptable alternative. We do not recommend the use of an 18” Stilson to tighten end caps. The torque from an 8” adjustable spanner is more than enough to create a good seal. DO NOT USE LINSEED OIL BASED SEALANTS.

Maintenance Tips

Removing Rust

Rust usually occurs when cast iron has prolonged contact with strong oxidants, impure or salted water, acid, or polluted air.

There are a number of homemade solutions you can use:


1.White Vinegar

Vinegar has the necessary properties to help dissolve rust from cast iron. Soak a towel in vinegar and simply wipe away the rust. For best results leave the vinegar on for at least 24 hours.


2.Lime and Salt

First, sprinkle salt over the rust and squeeze the lime juice over the rusted area. Leave this for a few hours before rubbing it off. You can use the skin of the lime to avoid damaging the radiator. A lemon can also be used.

3. Baking Soda Paste

To make baking soda paste, simply mix 1 tbsp of water and 1 tbsp of baking soda together. Wipe the past over the affected area. Leave for a short period of time and wipe away with a clean towel.



A major cause of corrosion in your radiator is sludge. This black substance can build up over time and cause rust to develop within your radiator. This can lead to pinholes and as a result leaks can occur.

Sludge can cause damage to your entire heating system, resulting in performance issues. Regularly maintaining your heating system will ensure that sludge won’t become a problem.

Using magnetic filters will help to avoid rust developing as it catches the sludge before it has a chance to develop.  Always consult a heating engineer to advise on whether you can fit a magnetic filter to your system.

Paint / Finishes

We highly recommend using our experienced painters to finish your radiator at the factory prior to delivery. It offers protection from rust and reduces wear and tear damage.

If finishing the radiator at home, ensure you use an appropriate heat resistant paint and cover all of the radiator as some areas can be easily missed and therefore will be unprotected from rust.

Polished Radiators need to be looked after and regular maintenance is required to ensure a long–term rust–free finish. Applying a thin coat of lacquer or oil will help to preserve the finish for years to come.

To remove rust spots if they appear, gently rub with light wire wool and touch up with a thin layer of lacquer or oil.

Choose from 22 designs and over 50 models visit our cast iron radiator page to find the perfect radiator for you!

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