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Cast Iron Radiator Construction


Cast Iron Radiator Construction

Have you ever wondered how your cast iron radiator was constructed?

We recently had a customer ask us to repair a cracked radiator which had been left in an empty house over winter… with disastrous results! – Here’s what frozen water can do to pipes and radiators.

Cast iron radiator construction
A combination of inferior quality cast iron and frozen pipes did this to the radiator

Radiator frozen pipe damage

A combination of inferior quality cast iron and frozen pipes did this to the radiator, imagine what it did to the rest of the house? Note to everyone (and self) double check insulation on pipes and make sure frost guard is switched on or system emptied if house left unoccupied.

(Do see our article “how reliable are reproduction radiators”)

Anyway, we were happy to help. In this case it meant dismantling the radiator, removing the broken section and re-assembling the radiator (now one section shorter). Not only was our customer very pleased that they didn’t have to go and buy a new radiator it gave us the perfect opportunity to show you how, once cast, the individual pieces of this type of construction of radiator are put together. Most cast iron radiators, old and new, use the same principle. (although some use a different construction type called “push nipple”)

Cast iron radiator construction
The individual pieces of this type of construction of radiator

At the top and bottom of each section there is a hole on each side that allows the hot water flow freely from one section to the next and through the entire length of the radiator. All these holes are tapped into a female profile so they can accept a large hollow bolt called a “nipple”. On one side of the section holes are tapped with a right hand thread and on the other side the holes are tapped with a left hand thread. The nipples are tapped to a male profile so they can be screwed into the sections. One half of the nipple is tapped with a right hand thread and the other half tapped with a left hand thread.

The hollow inside of the nipple is shaped so a tool can be inserted into it and the nipple turned. On the outside of the nipple (in-between each section) a gasket is placed.

The nipple acts in the usual manner – clockwise to tighten and anti-clockwise to loosen.

See our Cast Iron radiator Construction video

a tool can be inserted into it and the nipple turned

Well, new radiators are relatively ‘easy’ but for original radiators that have been together for up to 120 years the case is entirely different. Fort these we need to make special tools and be prepared to work much harder. You can see us dismantling an original radiator in our video.