Introduction

Conventional steel-panelled radiators are hung on brackets fixed securely to the wall. These generally consist of a piece of angled steel with hooks to match the slots in the brackets welded to the rear face of the radiator. Since they are fairly heavy when full of water, the fittings and fixtures must be strong. They must also be aligned accurately so that the radiator will be square and level. Some radiators may have more than two brackets, but this will depend on the size.

If a radiator is corroded or damaged it will have to be replaced. Where possible, try to obtain exactly the same model as the one you are replacing; that way you can simply drain and remove the old one, clean up the threads of the new adaptors

and blanking plugs, wind PTFE tape round them, screw them into the new radiator, hang it on the wall and connect the valves to the adaptors. However, if your system is a little elderly, you may have to settle for a different pattern of radiator, and chances are you'll have to fit new wall brackets and alter the water pipes.

Each radiator will have four threaded tappings - one at each corner - used for the necessary fittings to suit the pipework runs. Generally one of the top tappings will not be used and will therefore be blanked off. The second top tapping is fitted with a bleed valve while the two bottom tappings are used for the manual or thermostatic control valve and a balancing lockshield valve.

Drain the system, remove the old radiator and take the old brackets off the wall. When you have re-connected the plumbing, allow the feed and expansion tank to re-fill and the system will fill automatically. Then, bleed all the radiators.

If you want to move a radiator to a different position in a room, perhaps because you are rearranging the furniture, you will have to take up the floorboards. Sever the vertical portions of the old feed and return pipes and either cap the T-joints or replace them with straight joints. Use capillary or connection fittings to connect new vertical pipes to the original pipework, making sure they align with the radiator valve. Re-hang the radiator as described below.

Step by Step Instructions

1 Measure the new radiator

Lay the new radiator face down on the floor and slide one of its brackets onto one of the hangers welded to the back. Measure from the top of the bracket to the bottom of the radiator and add 100-125mm (4-5in) for clearance under the radiator.

2 Mark the wall

Using the distance just calculated, mark a horizontal line on the wall where the radiator is to be hung. Use a spirit level to ensure a true horizontal. Next, measure the distance between the centres of the radiator hangers and make two further marks on the horizontal line at that distance apart.

3 Fix the brackets

Line up the brackets, mark their fixing screw holes, then drill and plug the holes. Fix the brackets in place. Unscrew the valve adaptors from the bottom of the radiator with an adjustable spanner or hexagonal radiator spanner. Unscrew the bleed with its key, and the blanking plugs from the top of the radiator.

4 Fit the valves

Fit the valves so you can see where the pipes will come through the floor. With the protective plugs removed from the radiator, wrap at least five turns of PTFE tape around the threaded tails of the valve and screw them hand-tight into the radiator. Make sure the PTFE stays on the thread as you tighten.

5 Roughen the thread

If the PTFE tape starts to run over the thread, undo the valve and slightly roughen the thread with a hacksaw blade. Re-tape the thread more tightly, screw in to the radiator and then tighten first by hand, then with a spanner or Allen key. When the tails are tight, attach the body of the valves.

6 Marking holes for drilling

There are two ways you can run pipes: along the surface of a wall or under the floor. If the pipes are coming from beneath a wooden floor, hold a try square in line with the centre of the valve in two positions and mark the point on the floor. Where the two lines cross indicates the centreline of the valve.

7 Drill holes

Check there are no pipes or cables hidden beneath the floor. Use an 18mm (3/4in) or larger wood bit to drill into the wooden floor. This will allow for clearance around the pipe. If the hole is too small, when they are full of hot water they will expand and creak against the floor.

8 Connecting pipework

If access is restricted, use push-fit joints. These are reliable but the pipe ends must be evenly cut so they don't damage the rubber seals. If you prefer, solder the joints and, if possible, make up lengths of pipes with elbows and solder them outside. You should be able to push them through the holes into the radiators.