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When winter hits London, a good heating system isn’t just nice to have—it’s a must. So, there’s nothing more annoying than one radiator not working while the rest of the house is warm and cosy. Whether it’s a freezing bathroom or a chilly living room, even one cold radiator can throw off your comfort.

If you’re asking, “Why isn’t this radiator getting hot?” don’t worry—we’ve got you covered. In this guide, we’ll break down the common causes, share some easy fixes, and give you tips to keep your radiators running smoothly. And if you need some expert help, Serviceteam is here to get your heating system back on track.

Understanding the Issue: Why is One Radiator Not Working?

a-person-touching-the-radiator-in-their-home Airlocks in the System

Air trapped in the radiator can stop hot water from flowing properly, leaving it cold or only partially warm. The good news? Bleeding the radiator is often a quick and easy fix.

Faulty TRVs

Thermostatic radiator valves (TRVs) control the flow of hot water to radiators, ensuring efficient heating. Over time, TRVs can seize, especially in older radiators, stopping hot water from entering and leaving the radiator cold. Identifying a stuck TRV is key to quickly resolving heating issues and restoring your system’s functionality. Keep your radiators running smoothly by addressing this common problem.

Sediment Build-Up

Over time, sludge and debris can collect inside radiators, especially in older systems that haven’t been cleaned. This blocks the flow of hot water, but a professional power flush can help get things back to normal.

Central Heating Pump Problems

The central heating pump is what moves hot water through your radiators. If it’s not working properly or isn’t set up right, radiators far from the pump might struggle to heat up. A quick check of the pump could be the answer.

Balancing Issues

Sometimes, the reason behind one radiator is not getting hot isn’t with the radiator itself but the whole system.

An unbalanced heating system can favour some radiators over others, leaving a few in the cold. Balancing the system can make sure heat is spread evenly.

If one radiator isn’t working, identify the cause, it could be trapped air, a stuck valve, or a larger system issue and if you’re unsure, call a professional heating engineer—they’re here to help!

You can rely on Serviceteam for professional radiator replacement services in London.

Diagnosing the Radiator Problems

Here’s how you can diagnose why one radiator not working:

Check the temperature:

  • Is your radiator cold all over or just in certain spots?
  • Cold at the top but warm at the bottom? There’s probably some trapped air.
  • Cold at the bottom? That could mean sludge build-up.

Take a look at the valves:
Make sure both the Thermostatic Radiator Valve (TRV) and the lockshield valve are fully open. Look for any visible damage or leaks that might mess with how it works.

Check other radiators:
If more than one radiator is playing up, the problem might be with your central heating pump or an imbalance in the system.

Listen for weird noises:
One radiator not working, and you can hear banging or gurgling sounds? That’s often a sign of trapped air or sediment blocking things up.

Keep an eye on boiler pressure:
low boiler pressure, it can stop your radiators from heating properly. Check the pressure gauge and adjust it if needed.

If none of these fix the issue, it’s probably time to call in a professional. Catching the problem early can save you time and money down the line!

How To Fix One Radiator Not Working?

a-young-man-is-repairing-a-radiator-at-home Bleeding the Radiator

If there’s trapped air causing a blockage, bleeding the radiator is an easy fix. All you need is a radiator key, which you can grab at most hardware stores.

  • First, turn off your heating system to avoid any risk of burns.
  • Find the bleed valve at the top of the radiator and pop in the radiator key.
  • Slowly turn the key counterclockwise—you’ll hear a hissing noise as the air escapes.
  • Once you see water dripping out, close the valve tightly.
  • Wipe up any mess, turn the heating back on, and check if the radiator heats up evenly.
But if one radiator not working after bleeding, then it might be best to call in a pro to take a look at your heating system.
Cleaning or Power Flushing

If sludge or grime is clogging your radiator, it might need a good clean. Smaller blockages can sometimes be handled manually, but for a thorough job, a professional power flush is your best bet. This clears out sediment from the entire heating system, not just the radiator, improving efficiency and performance.

Regular maintenance can also help you avoid sludge build-up in the first place.

Opening or Replacing Valves

If the radiator valve is stuck or broken, try gently turning it to make sure it’s fully open. If it’s still not working, you might need to replace it.

A new valve will restore proper water flow and get your radiator back on track.

Resetting the Heating System

Sometimes, a quick reset can fix one radiator not working. Turn off your boiler, wait a few minutes, and then restart it. This can help resolve circulation problems or small glitches.

IMPORTANT
Just be sure to follow your boiler’s manual for safe boiler restarting.
Balancing the System

If some radiators are heating unevenly, your system might need balancing. This means adjusting the lockshield valves on each radiator to ensure water flows evenly throughout the system. It can be a bit tricky, so if you’re unsure, calling in a pro is a smart move.

Fixing Faulty TRVs

To see if your TRV is stuck, turn off the heating and make sure the radiator is cool. Take off the TRV head to get to the pin underneath.

  • Gently press the pin—if it pops back up, the TRV isn’t stuck, and you might just need to bleed the radiator.
  • If the pin is stuck, try adding a little grease and carefully loosening it with pliers. Just don’t use too much force—you don’t want to break it! If that doesn’t work, it’s best to call a qualified heating engineer to fix it safely.

By following these steps, you can handle most radiator issues, like one radiator not working and keep your heating system working like a charm!

Preventing Future Radiator Problems

Here are some easy tips to help you avoid problems:

  • Get Regular Maintenance: Book an annual boiler service for your boiler and heating system. It’ll keep things running efficiently and catch any issues before they become bigger headaches.
  • Bleed Your Radiators: Before the cold sets in, bleed your radiators to get rid of trapped air. This helps your system work better and keeps your home evenly heated.
  • Check Boiler Pressure: Make sure your boiler pressure stays between 1 and 2 bars. Too low or too high can mess with efficiency and cause trouble down the line.
  • Think About a Magnetic Filter: Installing a magnetic filter can trap sludge and debris before it clogs up your radiators. It’s a great way to extend the life of your heating system.
  • Call in the Pros: Always hire a licensed heating engineer for installations, repairs, or servicing. They’ll do quality work and ensure everything’s safe and up to standard.

Taking care of your heating system doesn’t have to be a hassle. With a little regular maintenance and help from the experts, you can avoid costly issues like one radiator not working and keep your home warm and cosy all year long!

How To Distribute Heat Evenly Across Radiators?

a-woman-is-warming-her-hands-on-a-radiator
  • Adjust Your Radiator Valves
    Take a look at each radiator valve and make sure they’re set properly. Balancing the valves helps hot water flow evenly so all your radiators stay warm.
  • Consider a Bypass Valve
    If your system struggles with pressure or water flow, adding a bypass valve can help. It keeps everything running smoothly and ensures consistent heating.
  • Check Your Thermostat
    Double-check your thermostat settings to make sure they’re right for your home’s size and layout. A poorly set thermostat can throw everything off.
  • Do Seasonal Check-Ups
    Before winter hits, give your heating system a quick once-over. Catching any issues early will save you from chilly surprises later.

Follow these simple steps, and you’ll have evenly heated radiators and a cosy home in no time!

Reliable Radiator Repair and Replacement in London

At Serviceteam, our expert engineers are pros at sorting out heating problems quickly and smoothly. Whether it’s bleeding a radiator, fixing a heating system, or swapping out faulty parts, we’ve got your back with reliable service designed for London homes.

Why pick Serviceteam?

  • Certified engineers who know their stuff.
  • Clear pricing—no nasty surprises.
  • Quick, hassle-free service to get your heating sorted.

Upgrade Your Heating with Professional Radiator Replacement

Is your old radiator underperforming? Trust Serviceteam for expert radiator replacement services across London. Our skilled engineers ensure a seamless installation, improving your home's comfort and energy efficiency.
    

Don’t let a cold radiator ruin your comfort. Give us a call today, and we’ll get your heating system running like a dream. We’re here to make sure you stay warm when it matters most!

Find our blog section, Boiler and Heating, for valuable insights and expert tips on all things heating.

FAQs

Why isn’t one of my radiators heating up?

If one radiator is staying cold while the others are working fine, it could be due to trapped air, a stuck valve, or sludge buildup. In many London homes, bleeding the radiator or flushing the system usually fixes the problem. But if one radiator not working after bleeding, it’s a good idea to call in a professional to make sure your heating system is running smoothly.

How can I figure out what’s wrong with my heating?

Start by checking the basics: is the boiler pressure okay, are the thermostat settings right, and are the radiator valves open? If you live in an older London property, there might be issues with the pipework, so keep an eye out for leaks or uneven heating. If you’ve tried all this and still can’t solve the issue, calling a Gas Safe engineer is your best bet—they’ll sort it quickly and safely.

How often should I get my heating system serviced?

Once a year by a Gas Safe registered engineer. Regular servicing keeps it running efficiently and safely, and it’s especially important for older London homes to avoid winter breakdowns. Need a reliable annual boiler service? Serviceteam is here to help!

Should I call a professional when one radiator not working?

If bleeding the radiator doesn’t do the trick, YES, it’s time to call a pro. A Gas Safe engineer in London can tackle issues like stuck valves, trapped air, or sludge buildup, making sure your heating system works perfectly and keeps your home cosy all winter long.