Adding a new radiator into an existing system is best left to a professional, but it's possible to update or replace a rusty unit with the same size new radiator using some basic plumbing know-how.
By George Clarke
Adjustable spanners
PTFE tape
Radiator key
Screwdrivers
Shallow bowl or pan
Old towels
A 600x600mm double radiator costs from £45
Three to four hours for novices
Some plumbing experience needed
Step One: Turn Off The Radiator
Turn off the heating and water, and allow to cool. Turn off the radiator by turning the plastic handle clockwise. At the other end of the radiator is a lockshield valve. Take off the protective plastic cap and use an adjustable spanner to close this valve by turning it clockwise. Make a note of the number of turns needed as the valve should be opened by the same amount of turns when the radiator is replaced. This will keep the system 'balanced' - distributing the heat evenly through the house.
Step Two: Bleed The Radiator
Bleed the radiator of air by using a key to open the bleed valve in one of the top corners of the radiator.
Step Three: Remove The Old Radiator
Remove the old radiator, leaving the two valves attached to the pipes. Grip the valve assembly with one wrench so that it cannot be pulled loose from the pipe feeding it. If you open the bleed valve at the top of the radiator, air will enter and allow the water to flow more quickly out of the radiator. Undo the nut completely.
Step Four: Drain The Old Radiator
Now, carefully undo the nut holding the radiator to the valve at the other end in the same way. Close the bleed valve. Lift the radiator up from its brackets and hold it at an angle over the bucket to finish draining. Radiators can be fairly heavy, so get some help.
Step Five: Attach The New Radiator
Wrap a short length of PTFE tape around the thread of the new radiator in a clockwise direction before fitting. Lift the radiator up onto the wall brackets and manoeuvre the valves at both ends so that they sit squarely onto the radiator connections. Hand-tighten the nut onto each valve, taking care not to cross thread them.
Step Six: Tighten The Valves
Holding the valve assembly with a pipe wrench so that it can't be pulled off the pipe, use a second wrench to do up the connecting nut. Remember, you can tighten a joint if it leaks, but if it has been over-tightened, you will need to dismantle it and start again.
Step Seven: Open The Flow Valve
Having tightened both connections, open the bleed valve at the top of the radiator. Now open only the flow valve at the bottom of the radiator. This will be the valve used for turning the radiator on and off. This will allow the water to flow in, and air to be pushed out at the top. When water starts to leak from the bleed valve, close it.
Step Eight: Open The Return Valve
Now open the return valve at the bottom of the radiator by the same number of turns used to close it originally, allowing water to circulate through the system. Check both connections for leaks, turn on your heating and check again for leaks.
Illustrations: Ed Roberts
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