Are Your Radiators Not Hot Enough? Here’s Why

If you have luck like me, you really needed your radiators to heat up before searching this article up. Of course, they didn’t do that – otherwise you wouldn’t be here. If your radiators are not hot enough, I’ve got good news and bad news. The good is that some of these issues can be easily fixed. The bad news is that if these solutions don’t fix your problem, you likely have a much larger issue on your hands.

The most common reasons that radiators are not hot enough are trapped air, boiler or central heating problems, seized or old valves, and dirty radiator interiors.

Let’s get into it.

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The 4 Primary Causes of Radiators Not Being Hot Enough

Let’s start with the simple fixes and move onto the more complicated ones with time. That way nobody wastes their time without absolutely needing to. To do most of these fixes, you’ll need at the very least need your radiator key and a wrench.

Trapped Air

If you work visually like me, check out this video guide on how to bleed a radiator. Otherwise, read on!

If only some (or just one) of your radiators are not hot enough, a likely cause is trapped air. This is especially common when you’re turning them on for the first time after summer. To check and fix this:

  1. Feel the bottom of the radiator. If it’s hot at the bottom and cold at the top, that’s a sign of trapped air.
  2. If this is the case, grab your radiator key and locate the bleed screw on the side – it looks like, well, a large screw. They’re generally pretty hard to miss.
  3. Turn the key and slowly unscrew the bleed screw. You’ll hear a hissing sound – that’s where you should stop unscrewing. This can take up to one minute.
  4. Once that sound is gone and water comes out of the hole, close the screw back up tightly.
  5. You should have a fully-functioning radiator after this!

If that doesn’t work, move onto the next item in the list.

Read Next: How much water is inside a radiator?


Radiator valve

If your entire radiator is cold, rather than just on the top, consider looking at your valves. All you can do at home easily is ensure they’re open on both sides – if not, you’ll need to call a professional to confirm that’s the issue and fix it.

Calling a professional is even more important if your valves have seized and caused it to stop working entirely. You’ll likely need a replacement part or two, so it’s generally best to let people who do this for a living perform the repairs. Sit back, make a drink, and you’ll soon have a toasty home again.

Read Next: Why your radiator bleeding valve is leaking.


Dirty radiator

If your radiator is cold at the bottom only, that could be a sign that it needs to be cleaned out. Just like everything else in life, radiators work best when they’re clean, and when muck builds up over time, problems can arise. This process is, for all intents and purposes, just removing the old water and flushing the radiator with clean water.

First, it’s good to check that this is actually the problem. If you have dirty water coming out when you bleed your radiator, that’s a good sign it needs a flush. Other signs include needing flushing more often than usual, loud noises, or a broken or leaky heat pump. To flush your radiator at home:

  1. Turn your heat off and let it cool down. You don’t want to get burnt.
  2. Cover your floors with something you don’t mind sacrificing, like a dirty old towel. This will protect them from the gunk.
  3. Turn off both valves. Turn the thermostatic radiator valve (TRV) clockwise to the off position. Lockshield valves will require you use a spanner to turn them off.
  4. Loosen your TRV with your spanner.
  5. Bleed your radiator as detailed above.
  6. Drain it and let all water come out through the bleed valve.
  7. Remove the radiator and take it outside.
  8. Flush it with a hose, using clean water. You can use a rubber mallet (if you have one) to knock loose extra-pesky gunk.
  9. Reconnect the radiator and check your boiler pressure. If you’re not comfortable with any of this, ask a pro for help.

Read Next: How to calculate the costs of running your oil-filled heater.

When to Call For Help

Radiator repairman

If you’ve tried the above steps or are uncomfortable performing them, call a heating engineer for help. They’re going to be able to accurately pinpoint the issue and solve it much faster than you could likely ever do – after all, it is their job to do exactly that. It may seem expensive, but you know what’s more expensive? Having to pay them to come and fix something you did without actually knowing how to do it.

And if none of these issues solved your problem, it’s very likely that there are larger, underlying problems with your boiler or central heating system. Unless you’re a qualified engineer, it’s likely that you’ll need to call for help with this. If you don’t, or you put it off, you run the risk of having much more serious issues down the line due to neglect.

Read Next: Radiator crackling and other noises.

Final Thoughts

Radiators are truly wonderful creations, though they require a bit of maintenance every now and then. If your radiators are not hot enough, go through the above list. Knowing how to bleed your radiator and perform basic cleaning will go a long way towards helping prolong your radiator’s lifespan, and will save you money on repairs.

If your radiator is cold at just the bottom, check your valves. When the radiator is cold at the top, you likely only need to perform a bleed. And if it’s cold everywhere, you need to inspect your home’s boiler or central heating, flush the radiator, and likely call for help. There’s no sense in putting off problems that could be very serious.

If you’re tired of dealing with a radiator, consider investing in a conservation heater to save some money! And remember – professionals exist for a reason, so use them! There’s no shame in hiring someone more qualified than you to fix a problem while you sip at that hot toddy in peace.

Read Next: Fix a radiator that won’t turn off.