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Cooling And Heating

One Radiator Not Working, Cold Pipes [Solved]

Written by Dale Richardson - Updated: June 23, 2023

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And we're back again with more tips on how to troubleshoot radiators. If you have one radiator not working and cold pipes, this is the place to look for more information. Specifically, that's because we've got other guides for fixing radiators . Check them out if you're stuck or need a bit of extra advice.

The two most common causes of a single radiator not working with cold pipes are air trapped in the radiator or a stuck valve.

Keep reading for a thorough explanation of how to bleed your radiator, fix stuck valves, and get your home nice and toasty once again.

READ NEXT: Heating off but radiator hot? Here's why.

One Radiator Not Working, Cold Pipes - Top Causes

Especially with old radiators, having your valve get stuck due to constant fluctuations in heat is extremely common. While this is especially bad with older radiators, your shiny new one may have the same issue. Another possible cause for issues with your radiator(s) is air getting trapped inside the machine. This is, luckily, very easy to solve in a few minutes.

Let's get into it, shall we?

Stuck Valves



Check out the valves if you have the heating on and a single radiator is out while the others are working. The thermostatic radiator valve (TRV) controls the flow of hot water to and from your radiator. If this gets stuck, bent, or warped, it can cause your radiator to stop working quite as well.

To check your valve, you'll need to remove the rotating head that's attached (usually on the side). It's the knob you use to adjust temperatures on the radiator. There will be a raised pin beneath that you can press with your finger.

When you release the pin, it should rise back up - if it doesn't, or does so very slowly, the pin is likely damaged. If you have to apply a large amount of force to the pin, this is a bad sign, as you shouldn't have to force it.

You can try to use some pliers and grease (such as WD-40) to loosen the pin, though you risk damageing it further, so be careful. If you do damage the pin, you'll need to call for some help.

READ NEXT: Learn more about why your boiler is clicking (and other noises).

Trapped Air



If the TRV isn't the cause of your problems, you likely have air trapped in the radiator. The air tends to gather at the highest points of your radiator and get trapped. It will prevent the distribution of heated water, causing cold pipes near the top. To fix this, you'll need to bleed your radiator. Here's how:

  1. First, open all radiator thermostats and run the heat at full temperatures for at least ten minutes.Next, you’ll off the circulation pump and wait for your radiators to cool – this usually takes no more than an hour.
  2. Next, locate your bleed screw on the side. This is generally rather hard to miss and looks like, well, a large screw. 
  3. Start by using your bleed key or a screwdriver, turn that screw so that you hear air hissing out.
  4. Once you’ve done this for ~30 seconds to one minute, water will begin to escape. Tighten the screw to stop the flow of water and repeat this process for all of your radiators.
    • This is good to do every year as general maintanence. Even if your other radiators are working perfectly, there’s no harm in doing it all at once to prevent issues down the line.

If this seems too involved for your level of technical expertise, call a pro. You don't want to damage anything by doing something you're uncomfortable with accidentally.

Read Next: Radiator crackling and other noises.

Additional Causes for One Radiator Not Working, Cold Pipes

If neither of these solutions solved the problem, but you don't want to call in the big guns yet, check several other things. You'll want to take a look at your water pressure and the boiler or water heater you have. If the radiator isn't the issue, the fault may lie in your home's framework.

Read Next: How much water is inside a radiator?

Water Pressure



Look for the manometer for your boiler. Generally, manometers are directly attached to your boiler or the point that your water supply and boiler meet. It will look like a small gauge, similar to those on your car's dash.

A residential gas boiler's ideal water pressure is usually around 1.0 bar - water pressure is displayed on the meter with coloured sections. If your water pressure is lower than ideal, increase it. However, if this doesn't work, call for help - it's likely a more complicated fix than you can perform at home.

Read Next: Radiator crackling and other noises.

Boiler/Heat Pump Faults

One final source of your problem is the boiler or heat pump itself. First things first - boilers are complicated machines that require electric and plumbing knowledge. If you don't have those bits of training, you'll want to call a Gas Safe registered heating engineer if you're even slightly uncomfortable with the following.

With that out of the way, let's get onto what you need to look for. Begin by double-checking that you have your boiler on the proper settings. Check for fault codes that are displayed (they'll be obvious) and that the boiler is not on summer mode. Next, ensure you have the boiler set for heating and hot water - if not, fix the settings.

If you have a heat pump, make sure it's working properly and double-check the outdoor unit. If it's dirty, clogged, or blocked, fix the block. Finally, if either your heat pump or boiler are making odd noises - call for help. That's a sign that something is wrong internally and is exactly the type of thing you call a licensed technician for.

Read Next: Towel radiator not working? Try this.

Final Thoughts

Radiators are complicated machines that require multiple small parts to work in perfect unison. If you have an old radiator, check the valves and ensure you've recently bled your radiators. These solutions will, nine times out of ten, fix one radiator not working with cold pipes. If these problems aren't solved by bleeding your radiator and checking the valves, move onto the boiler and water pressure to troubleshoot.

While you can check the boiler, heat pump, or water pressure yourself, any repairs need to be made by a professional. Keep an eye out for fault codes, blockages, proper settings, and that they're actually on . If you hear odd noises or feel uncomfortable with any of this, it's time to call in the big guns. Make yourself a drink, sit back, and let the pros deal with the problem.

Read Next: Why your radiator bleeding valve is leaking.

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