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Plumbing FAQ: Why is my bathroom radiator only getting hot at the bottom?

If your bathroom radiator is only getting hot at the bottom and remaining cold at the top, don't worry - there's hopefully an easy fix.

As your central heating system pumps hot water around, small air bubbles can begin to form. Naturally, these small pockets accumulate - typically high-up in the central heating system.

Due to the design of bathroom towel radiators, it is easy for this air to accumulate and become trapped at the top of the radiator. Resulting in the top of the radiator remaining cold. This air needs to be released from the radiator with a procedure commonly known as "bleeding the radiator".

The only tool you should need to bleed the radiator is a radiator bleed / vent key - available to purchase at our plumbing and heating counter.

You'll also need to locate the filling loop on your boiler, ensure it is functional, and take note of what the correct operating pressure of your boiler is prior to bleeding the system.

If you're in any doubt, we'd recommend arranging for a plumber to fix the issue for you.

Warning: Before bleeding the radiator, ensure that your central heating is not running and has cooled down, as the hot steam / water has the potential to cause burns.

With the key in hand, simply loosen the vent bolt slightly on the top of the radiator until you can hear air hissing out of the radiator. Once all of the air has been released, water will then start to be released from this vent. As soon as water appears, simply re-tighten the vent bolt and you're all done.

It may also be worth checking all of the other radiators for air while you're at it - using the exact same technique.

Before you switch your central heating back on, you may need to increase the pressure in the central heating system. This is usually done via the filling loop attached to your boiler.

Increase the pressure to the correct operating pressure and you should be good to go.


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