How to Change Valves on Hot Water Radiators

White radiator in a room
  • 1-2 hours
  • Intermediate
  • 20-50
What You'll Need
Pipe cutter (optional)
New valves
Tape dope

You may need to change the valves on a hot water radiator from time to time. This needs done when they get old and rusted and become difficult to turn. The valves must be in good working condition if you want to successfully use the radiator. Purchasing a new radiator every time the valves become rusted or broken is expensive. It is also unnecessary as replacing these isn't terribly difficult. Follow the simple steps below to change the valves on your radiator on your own.

Step 1 - Cut the Power

Turn off the power to the water radiator. If you are working with a gas radiator, then turn off the gas supply too; you can do this using the gas valve, usually found towards the bottom of the unit. The power and the gas must be turned off if you want to safely work on your radiator.

Step 2 - Drain the Water

Just below the relief valve, you should see a drain valve. Open this to allow the water to drain from the system into the nearest floor drain. It should take less than five minutes to completely clear the radiator. If the nearest floor drain is too far away, then it may be necessary to use a large bucket to carry the water to the drain. Be sure to not move on to the next step until all of the water has successfully drained from the radiator.

Step 3 - Prepare the New Valve

Wrap the threads on the new valves with pipe dope, which will help to seal the threads once you install the new valves. Be sure to not use too much as this can make working with the valves difficult. Only use enough to cover the threads of the new valves.

Step 4 - Remove the Old Valves

red shut off valve

Use a wrench to remove the old valves. If they are severely damaged - like from rust - you may need to use pipe cutters. If you have to use this route, you will need to install a new stem as well.

Step 5 - Replace the Valves

Insert the new valves into the stems. Twist the new valves on to the stem until they catch. Use the wrench to tighten them down, but not too much as this can damage the new stems. Only tighten them until they can no longer move, and then stop.

Step 6 - Turn the Water On

Restore the water supply, and test to ensure the new valves are operating properly. If you see water leaking from around the valves, you will need to turn off the water again and remove the valves. You may just need more pipe dope to correct this. Once you confirm that they are properly installed, you can restore both the water and the power.