How to Replace A Radiator Valve (Without Draining The System!)

Radiator valves are essential components of any central heating system – they allow us to control the flow of hot water through each radiator, so keeping them in good working condition is important to improve the overall efficiency of your radiators and heating system.

Many online guides explore how to change a radiator valve whilst also draining the heating system. However, this isn’t ideal as you’ll likely have to replace the inhibitor in your system. In this guide, we’ll show you how to replace the valve without draining the central heating system – making it a much quicker and more economical task!

If you’re unsure how to change a radiator valve – or if you’re wondering what can go wrong, this is the blog post for you – we’ll cover the exact steps you’ll need to take, whilst considering the common problems you might find with radiator valves. 

So whether you’re replacing a broken valve or just looking to upgrade a manual valve to a thermostatic radiator valve for improved radiator efficiency (TRV), read on for instructions on how to get the job done quickly and easily. 

Steps to install a new radiator valve without draining the system:

Step 1: Turn The Boiler Off

The first step to changing a radiator valve is turning off your boiler at the fused spur switch on the wall. This will ensure that the boiler doesn’t engage and push more water through the system whilst you’re working on it, which would lead to quite a considerable leak!

Step 2: Bleed The Radiator To Release The Pressure In The System

Use either a bleed valve key or a screwdriver to bleed the radiator – simply twist the valve anti-clockwise a quarter turn or until you start hearing a hissing sound, this means that the pressure is being released from the radiator. This will ensure that the pressure in the system is low enough for us to replace the valve.

Don’t be too concerned if you see water escaping from the unit, this is normal so just ensure you have a towel or container ready to catch the drips. You’ll want to keep the valve open until the flow has reduced to a very small, light trickle. This means that the pressure in the system is low enough for us to remove the valve.

Step 3: Close The Lockshield Valve Inlet

Remove the cap from the top of the lockshield to expose the pin (this will be on the opposite side of the radiator from the one you are replacing). Simply use your wrench or adjustable spanner to turn the pin clockwise – this will ensure that there is no more water entering into the radiator whilst we remove the valve from the opposite end of the radiator.

Step 4: Prepare The Replacement Valve & Surrounding Area

Now that we’re ready to remove the old valve and replace it with an updated, newer TRV valve, we want to ensure that the area is prepped for any spillages or leakage. There will likely be some water that comes out of the radiator so make sure you’ve got your towels and container to hand!

To prep your new radiator valve, simply remove the nut and olive from the unit – we already have these in place on the existing setup so there’s no need to use these. Just take a minute to visualize the orientation of the valve so that the thermostat is facing the right direction before committing to fitting the valve. The connections should simply match your existing valve orientation and position.

Finally, ensure that the new valve is shut (it should be turned fully clockwise). This means when we’re attaching it there’s no way for the water to run through the valve – making it even easier to control any leakage that does run out whilst making the replacement.

Step 5: Loosen The Bottom Nut

Now we’ll need to loosen the bottom nut underneath the old valve, start slow with a small 1/4 or 1/2 twist – just enough until you feel the friction release. You may notice a few drips so just wipe them away with your towel.

Step 6: Loosen The Side Nut

Carefully loosen the nut that attaches the valve to the radiator itself. It’s very important to secure the valve itself whilst making this adjustment. If you try to force the nut loose without supporting the valve it is possible that the copper piping may become misshapen or bent. A gripper tool works well here – simply twist the nut with one hand whilst holding the valve in position with your other hand.

Once the nut has been loosened with your spanner or wrench, you can usually use your fingers to finish off the rest of the way. Don’t be alarmed if more water begins to flow out – this is normal. You may need to work quickly though to reduce the amount of water lost from the system.

Step 7: Remove the Old Radiator Valve

Now we need to remove the old valve by gently pushing it free, there should be some flexibility in the copper or plastic piping but don’t create any kinks or bends. Be gentle, using a small amount of force to wiggle the valve free.

Step 8: Install The New Valve

Attaching a new radiator valve is relatively simple – all you need to do is place the TRV back in place of the old valve and start twisting the nuts back onto the threads. Start with the one connecting to the radiator for the smallest amount of water loss. Remember, the new valve should be in a closed position so that once the side nut is fitted the water should dripping into the container.

Again, it’s advised to use grippers whilst tightening the nuts to ensure that no kinks or bends are made on the copper piping. Hold the valve in a fixed position whilst twisting the nuts with your other hand.

Conclusion

Congratulations… you’ve just changed your own radiator valve from start to finish without breaking a sweat -and you did it yourself! If done correctly, changing your radiator valves should only take about 30 minutes at the most.

However, if at any point during this process something doesn’t seem right, make sure to call an experienced professional for help rather than attempting further DIY fixes, as these may end up making matters worse instead of better.

Thanks for reading – we hope this guide was helpful for any future projects involving changing a radiator valve in your home. 

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