C H O O S I N G C O LU M N C A S T I RO N R A D I AT O R S

T O M AT C H YO U R H E AT I N G R E QU I R E M E N T S

Radiators as part of central heating systems transfer

heat or thermal energy, usually from heated water or gas

to air, for the purposes of heating living spaces. The

term radiator is not strictly accurate as they do not

transfer energy by thermal radiation but rather by

convection. No matter what we call them though their

importance to us is based on how well they can heat the

spaces we live in. Radiators circulate fluid through

sections or pipes and have columns to increase their

surface area to allow for the diffusion of heat.

C H O O S I N G C O L U M N C A S T I RO N R A D I AT O R S T O

M AT C H YO U R H E AT I N G R E Q U I R E M E N T S

Cast iron radiators are made up of sections joined by

threaded nipples and each section in turn is divided into

columns. These columns can vary in number and include

4 and 9 column cast iron radiators. The manufacture of

the 4 column cast iron radiators as an Ideal Standard

occurred in the United Kingdom until the 1970’s and is

therefore the most likely to be found in older buildings.

They are often preferred by architects and clients wanting

to use traditional cast iron radiators since they provide

the retro feel but are also economical.

C H O O S I N G C O L U M N C A S T I RO N R A D I AT O R S T O

M AT C H YO U R H E AT I N G R E Q U I R E M E N T S

The period preceding the 1970’s also saw the use of 9

column cast iron radiators in spaces where height

restriction was a factor. For those of you renovating a

period house these radiators add just the right touch.

Radiator heat output is measured in Watts or British

Thermal Units (BTUs) and they represent the same

thing although they use different scales. To convert an

output measurement in BTUs to Watts you should

divide by 3.412.

C H O O S I N G C O L U M N C A S T I R O N R A D I A T O R S T O M A T C H

Y O U R H E A T I N G R E Q U I R E M E N T S

. Retailers will usually specify the output of the radiators

they sell and you will have to determine what your heating

needs are prior to making a purchase or consult an expert.

Usually there is a discrepancy between the heating

requirement and the radiator output so one would need to

purchase a radiator or radiators that exceed the heating

requirement and use thermostatic valves to regulate the

temperature.

C H O O S I N G C O L U M N C A S T I RO N R A D I AT O R S T O

M AT C H YO U R H E AT I N G R E Q U I R E M E N T S

When purchasing a radiator you would also come across

the term delta T. The delta (Δ) T value indicates the

difference in temperature between the water circulating in

the central heating system and the temperature of the

surroundings also known as the ambient temperature. The

temperature of the central heating system running in your

house is usually around 80°C, while you would generally

like to heat your house to around 20°C. Calculation of the

Delta T value would therefore be 80-20 = 60. In the

United Kingdom outputs are usually shown at operating

temperatures using delta T60.

C H O O S I N G C O L U M N C A S T I RO N R A D I AT O R S T O

M AT C H YO U R H E AT I N G R E Q U I R E M E N T S

Knowing the various specifications and terminology

associated with column cast iron radiators is a quick way

to match your radiator to your heating requirements.

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