How to Change a Hydronic Radiator Valve

Before you start changing the radiator valve, go to your boiler and turn it off at the powerpoint.

Most importantly: ensure that the water is off by closing the valve on the mains water line coming into your system. The water line should be identifiable as the smallest copper pipe coming into the boiler. There is no harm in simply closing all valves.

Then, drain the system by opening the drain valve on your boiler to remove as much water from the pipework in the house. Note – not all water can be removed in this way, you will get water leakage from the panels and valves when you open them.

If your system was running and is hot, you should wait around an hour to let it cool down before starting your radiator valve changeover.

Now it’s time to start changing your radiator valves.

Start by closing the on/off valve by turning it clockwise like a tap. Then go to the lockshield and remove its cover, usually done by unscrewing a cap. Once the cap is removed you’ll see the lockshield adjustment, this needs to be closed by using a suitably sized Allen-Key or a Flat-Head Screwdriver that fits.

By closing the valve and lockshield, the water will remain in the lines when you undo the valves from the radiator ensuring less water to capture.

Place your towel around the floor area under the valve to capture any spills, and place your bucket under the valve.

PRO TIP: A paint tray is a great size to get under your valve to capture the water.

Take your pair of grips and spanner and crack open the nut that connects the valve to the radiator panel so the water begins to drain. You’ll have to open the air bleed so that the water can flow, and you will likely need to empty the tray a few times before your radiator panel is empty.

Now open the valve to ensure any water in your pipes is also drained.

Repeat for the other side of the panel.

Using your tools, unscrew the valve from the panel completely, then unscrew the valve from the pipe. You will have to unscrew the valve to panel connector using a large Allen-Key or Screwdriver also.

Remove all parts that are attached to the pipe so that you are left with a radiator panel with no fitting and a bare pipe.

Screw the new panel connector, that came with your valve, into the radiator panel, and slip over your pex or copper pipe connector on your pipe. Fit your valve to the pipe connector loosely, as well as the panel connector so that the valve is nice and straight.

Tighten each nut firmly ensuring that the valve stays in a straight position.

When you’ve connected all new valves and lockshields, it’s time to check for leaks. It’s best to do this with a second pair of eyes, so you don’t have a large clean up if you happen to have a large leak. First checking for leaks on the pipe side of the fitting by turning the valve and lockshield off.

Now you can turn the mains water back on at the boiler and check for leaks on any hydronic radiator valve you’ve changed over. When you’re confident there are no leaks you can open each valve and lockshield and check for any leaks on the panel connection.

When you have eliminated any potential leaks, it’s time to fill your panels one by one. This is done by opening the air bleed so that the water pressure can push the air out allowing it to fill with water. Have a bucket and towel ready at the air bleed.

Close the air bleed once the panel is full of water, you will know the panel is full when water starts to come out in a steady stream.

It is best to check all other panels for air by opening the air bleed.

When you turn your system back on, it may have air remaining in it. This air will usually be pushed to one point. You may have to (again) go panel to panel to check for air by opening the bleed.

If you’ve wanted to know how to change a hydronic radiator valve and still have some questions, be sure to comment below and we’ll do our best to help you out.

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