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Oversize Radiator Assembly Guide

Home / Resources / Installation Guides / Oversize Radiator Assembly Guide

A brief guide to assembling oversized radiators

Watch our Assembly Video


1. Position the radiator and remove the bushes

illustration of cast iron radiator sections together cap to capa. Check you have all pieces of the radiator (refer to the Assembly Diagram) and place them as close as possible to the final installation location.

b. The plastic caps at the joins are colour coded. Place green next to green or yellow next to yellow, for instance.

c. Remove the end bushes [2] & [3] as required for assembly of your radiator. You may need to use the Castrads assembly tool in Socket Mode for this. See the Assembly Tool Quick Start Guide for more information.Illustration of oversized radiator sections side by side ready to assemble.

2. Insert the threaded nipples

a. Check that all joining faces are clean and free of paint, rust or remnants of previous gaskets. Use a sharp blade to clean them back to bare metal if necessary.

b. Optionally apply a coating of sealant such as Boss White to the internal threads of the mating radiator sections and a thin coating to the cleaned faces.

c. Insert a nipple by just a quarter turn into the top and bottom female threads on one side of the first join. Ensure thread orientation of the nipple matches that of the radiator part.Illustration of cast iron radiator assembly inserting threaded nipples and adding gaskets.

3. Add the gaskets

a. Add a gasket to each nipple so it sits in the central recess.

4. Hand tighten the joins

a. Set the depth stop to the correct position. The distance from the depth stop to end of the assembly tool should be about an inch longer than the piece of the radiator you are attaching.

b. Insert the assembly bar through the top joining hole until it engages with the correct nipple as indicated by the depth stop.Illustration of cast iron radiator assembly tool marking point for nipple.

c. Tighten the top joint about two turns. Pull slightly on the radiator to ensure the two pieces are connected.

d. Repeat at the bottom join, tightening only a couple of turns.

e. Repeat steps c and d, tightening each join a little at a time, until both are closed and hand tight.Illustration of cast iron radiator assembly cross section.

5. Close the joins

a. Attach the breaker bar to the assembly bar.

b. Fully tighten the top join with the breaker bar.

c. Repeat on the bottom join.

d. Finally, repeat steps b and c on both joins to ensure a watertight seal. The breaker bar is designed to be long enough that an average adult placing their full weight on the end of the bar will generate sufficient torque at the join to form an effective seal.

6. Additional joins (if applicable)

You will need to repeat steps 2 to 5 for each additional join if your radiator has been delivered in more than two parts.

7. Insert the bushesIllustration of cast iron radiator assembly inserting the bushes.

a. For each bush, check that all joining faces are clean and free of paint, rust or remnants of previous gaskets. Use a sharp blade to clean them back to bare metal if necessary.

b. Add a gasket to the bush.

c. Insert the bush into the radiator.

d. Tighten the bush using the Castrads assembly tool in Socket Mode.

e. Repeat steps a to d for each bush that has been removed.