How to Add a Radiator

The problem with radiators is there are never enough of them to go round and often they’re the wrong place. The quickest and easiest way to upgrade your central heating system is by adding a radiator – but why pay someone to do it when you can follow our easy step-by-step guide and do it yourself in a day?

Our step-by-step guide shows you how to upgrade your heating system in a day.

Adding a radiator is a straightforward but time-consuming business, that’s why a plumber will charge you around £100 a radiator, plus materials, to fit one for you. If you have solid floors or need a particularly long run of pipes installed, you can keep on adding to that figure.

We’ve put together this handy guide to adding a radiator to your central heating system. The guide covers the most popular form of wet central heating: the open-vented system that uses flow and return pipes to distribute hot water from the boiler to the radiators and back to the boiler.

(MORE: See more DIY tutorials)

Tools needed

  • Butane torch
  • Pipe cutter
  • Adjustable spanner
  • Radiator valve key
  • Bleed valve key
  • Paint pen,
  • Tape measure
  • Drill and drill bits
  • Pencil
  • Screwdrivers,
  • Flameproof mat
  • Plastic hose/pipe cutter

Materials needed

  • Pre-soldered 15mm bends, tees and straight connectors
  • or Plastic quickfit 15mm bends, tees, straight connectors
  • 15mm copper pipe
  • or 5mm plastic pipe
  • Radiator
  • Radiator valves
  • Flux
  • Butane
  • Spare 15mm olives
  • PTFE tape
  • Pipe clips
  • Screws
  • Rawlplugs

Think carefully about where you are going to position your new radiator. Is one part of the room particularly cold? Will its benefits be negated by any future furniture moves? Also think about the rooms overall heating needs: this is measured in British Thermal Units (BTU) and most radiators have a sticker on them showing the BTU output. To work out how many BTU your room needs multiply the height by the width and length of the room (in feet) and then multiply this figure by four.

How many extra radiators can your boiler take? When a boiler is fitted the plumber takes into account the size of the house and fits a boiler with an appropriate BTU capacity. Normally, adding one or two radiators shouldnt cause any problems but its a good idea to check the boilers output (in the instruction manual or available from the manufacturer) and have an idea of the demands placed on the boiler by the existing radiators.

Step-by-step guide to adding a radiator

1. Once you’ve established where you are going to position the radiator, find the nearest pair of flow and return pipes that you can connect into. These can be positioned under floorboards or, as here, attached to a wall because of the solid ground floor.With the central heating system cold, turn the thermostat until it clicks and then touch both pipes. The pipe that gets hot first is the flow pipe from the boiler. Mark the flow and return pipes clearly with a paint pen.

2. Turn the boiler off and make sure that the water supply to the unit is turned off too. Attach a length of garden hose to the draincock on the radiator and run the hose to a point outside thats lower than the radiator. Undo the square key underneath the draincock and let the system drain down.

3. Releasing air from the radiator bleed valves lets air into the top of the radiator and forces out any water left in the system. Remember to do the valves up afterwards.

4. Find the centre point of the wall and draw a vertical pencil line at this point. Find the centre line of the radiator and then measure out from this point to the centre of the brackets. Transfer these measurements to the wall.

5. Some radiators come with a template for marking off the bracket hole positions. Offer this up to the lines already drawn and spot through with a pencil. If theres no template, slot the bracket onto the back of the radiator and measure from the base of the bracket to at least 50mm below the bottom of the radiator (some radiator manufacturers recommend up to 125mm clearance check packaging for details). Starting from the top of the skirting board, transfer this measurement onto the wall. If the system has drained down, you can now do up the draincock.

6. Put the base of the bracket on the line drawn in step 5 and then mark off the brackets top hole on the wall. Drill and rawlplug the wall, loosely attach the brackets at the top and then mark off and drill the bottom holes.

7. Wrap PTFE tape around the threaded parts of the radiator valves five times. This helps them to seal.

8. Fit the valves. Do up the main body of the valve with the correct hexagonal key thats available from DIY stores. Use an adjustable spanner to tighten the outer part of the valve onto the main body.

9. Hang the radiator.

10. Cut and fabricate the pipework required from the radiator back to the flow and return pipes you identified earlier. If youre working with copper pipe use a proper pipe cutter never a hacksaw. Mark out where you intend to fix brackets to support the pipe runs and screw them in place now.

11. If you are using copper pipes check that everything fits together before you start soldering and that no stresses are created when the pipework is attached.

12. Clean the ends of the copper pipes with wire wool.

13. Slide the retaining nuts and olives over the pipes that are connecting to the radiator valves and hold them in place while you tighten them.

14. For this part of the job were using pre-soldered or Yorkshire joints that just need to be heated evenly with a butane torch to melt the solder inside the joint and make a watertight joint. Use a flameproof mat behind the area being heated to prevent fires and the chance of un-soldering existing joints.

15. You can stop heating a pre-soldered joint when the solder appears in a ring around the edge of the joint like this. Dont forget: both ends of a presoldered joint must be heated at the same time.

16. Once you’ve got the pipework from the new radiator in the area of the pipe you plan to connect into, youll have to cut the pipe and insert a tee piece to take the feed. In this case were using a quick-fit plastic tee to demonstrate how traditional and modern plumbing components can work together.

17. Plastic pipe should be cut with the correct hose/pipe cutter rather than a hacksaw that tends to leave a frayed edge. Make sure the cut is square.

18. Before you connect plastic pipe to a connector, push an insert into the end to stop the pipe deforming in action.

19. Connect up the flow and return pipes to the pipes from the new radiator. If you have fitted a thermostatic valve to one side of your radiator and its not a bi-flow type then the flow feed must be connected to that valve. Refill the system by turning on the tap you turned off in step

20. Check for leaks and then bleed the air out of the radiators.