radiators not getting hot reason trv
Posted in

7 Reasons Why Your Radiators Aren’t Getting Hot Enough, Dec 2022

So why are Your Radiators not Getting Hot Enough?

Today’s blog is all about the reasons why your radiators aren’t getting hot enough. 

Around early December, you’d be forgiven for finally giving in and switching on your central heating. That sense of relief when the boiler fires up, you hear the water rushing through the pipes and about ten minutes later, your radiators are getting warm, your house cosy…and you’re already setting up the ground rules of the thermostat with the rest of the household.

At least, that’s the ideal situation. Unfortunately, this isn’t always the case, and many people are left continuing to sit in a cold room even with the heating on. If that sounds familiar, you’re in luck.

If your radiators aren’t getting hot enough…

Here’s what to do if your radiators feel cold, tepid, or just aren’t hitting the spot. By following this systematically, you can diagnose the issue by process of elimination.

Start at the beginning

Call us crazy, but the most logical thing to do is to head for your boiler and ensure it is behaving as normal. Things to look for:

●     That it switches and stays on (has electricity supply)

●     The gas or oil supply is switched on, and hasn’t automatically been switched off by a safety circuit within the boiler

●     If using oil, ensure there is oil in the tank

●     Ensure the water supply is switched on and that there are no leaks

●     Once set to run, there are no error or fault codes causing the boiler to switch off or interrupt the central heating

If your boiler passes these initial checks, and your radiators are still failing to get toasty, move to the next check.

Time at the bar

With an otherwise functional boiler, with supplies of power, fuel, and water, there’s one thing left at the boiler end to cast your eye over – the water pressure. When cold, the pressure on the gauge on the boiler should be approximately one bar, or at the lower end of the ‘green’ or ‘safe’ range.

If the water pressure is low, refill the system.  There’s likely to be a ‘tap’ to allow you to fill the system, then a second ‘tap’ which actually lets the water in. Keep an eye on the pressure gauge while filling and turn off both taps once the pressure gauge is reading in the low end of the safe range.

If your radiators aren’t getting hot at this point: un-roll your eyes, take a breath, and move on to check 3.

Valve Verification

It sounds ridiculous but check your Thermostatic Radiator Valves (TRV’s). Over the course of a spring and summer, particularly if you have small kids, the rotary valves on each radiator can end up being switched off, or onto a lower setting.

Also, ensure the rotary valves on either end of each radiator are in the on position. These are harder to accidentally turn into an off position, but stranger things have happened.

So, turn your valves onto the full heat setting and await the warmth. If this hasn’t fixed the problem, the valves may have seized - they may not turn at all, or the knob on the top of the TRV could shear from the actual valve preventing the hot water from entering the radiator. This one is harder to diagnose, so keep it in mind while you move onto the other checks to determine why your radiators aren’t getting hot enough.

trv radiator not working

Trapped Wind?

Ok, so you now know that your boiler is working properly, your water pressure is tip-top, and your radiators are indeed switched on - and yet, still, your radiators aren’t getting hot. So, what’s next?

Have a listen.  Can you hear trickling of water filling your radiator, or a hissing sound? Or perhaps the bottom of the radiator is getting warm, and the top is still stone cold? If these are the case, it *sounds* like you’ve got an airlock, and you need to bleed your radiators.

You can read an in-depth guide to bleeding your radiators in our other blog, but essentially it’s a case of opening the bleed valve at the top of the radiator until water starts to trickle out and then close it again. Doing this will force the trapped air out of the radiator, replacing the void with hot water and restoring functionality to your radiator.

Determine if your radiators are blocked

Often, the reason that radiators aren’t getting hot is not because of airlocks or boiler problems, but because the radiator is blocked up with a sludge comprised of rust, grime, and general silt which sits at the bottom of the unit and prevents the hot water from circulating properly. A tell-tale sign of this is a cold spot at the bottom of the radiator while the top is hot.

An additional issue associated with blocked radiators is that the sludge can travel between radiators and into the boiler, causing further inefficiencies and potentially expensive repairs.

There is a solution to this, however, in the form of a professionally administered Power Flush service which we offer. This is where the entire central heating system is flushed through at high pressure, clearing any blockages, and thereby increasing radiator efficiency by up to 30%.

Is it cold downstairs?

You may have noticed after all these checks that your radiators are successfully getting to temperature upstairs, and it’s the ones downstairs that are being problematic. If this is the case, it could be because your central heating system is unbalanced. This is in part because hot water rises, so naturally radiators upstairs will run hotter, but also radiators closest to the boiler, often upstairs, will heat up quicker than the others around your house.

Luckily it is possible to re-balance your central heating.  However if your house is any larger than a one-up one-down, you may want to find someone to help you.

The process is, in its briefest form:

Make sure all your radiators are cool and have been bled fully (there is no air within them)
Locate the lockshield valve on each radiator and open them (rotate left)
Turn your heating on and monitor the radiators to determine which heat up fastest - take note of these.
Turn the heating off and allow the radiators to cool down
Head to the radiator which heated up first, and fully close the lockshield valve - then open it a quarter turn
Repeat this for each radiator in the order, continuing with those that warmed up fastest. Those that warmed up the slowest need to be opened up more than the faster ones.
By doing this, you’re restricting the amount of hot water being supplied to the closer radiators and providing more to those that need it, resulting in the whole system heating up at the same rate.

If You’re Still Feeling The Cold…

If, after trying everything listed in this article, one, some or all of your radiators aren’t getting hot enough it’s probably time to call in some expert, professional help. Give us a call or book in online and a member of the Blackpool Boiler Installations team will be happy to give you some initial advice and arrange a time to call in and see what the problem is. Then your radiators will be warming up in no time and you can go back to arguing with the family over the thermostat!

Share this post
Need help with your boiler?
adam dilger blackpool boiler installations
Adam Dilger
Managing Director
We offer ground braking reliable heating solutions across the Northwest. With 20 years experience our engineers install, service and maintain your central heating systems. Connect with Adam on LinkedIn >>
View More Posts

Latest Posts






linkedin facebook pinterest youtube rss twitter instagram facebook-blank rss-blank linkedin-blank pinterest youtube twitter instagram