Why do I need a heat sink radiator?

It prevents boiler overheating and excessive system temperatures if all TRVs close and there is no bypass, allowing the boiler to shed heat safely.

Where should a heat sink radiator be installed?

Bathrooms are common because towel rails often run to dry towels, making them practical heat sink radiators.

Which products make good heat sink radiators?

Standard ladder heated towel rails in chrome, white, or black, and stainless steel models, are practical choices that provide continuous circulation and useful heat.

Ben Clarke

29 April 2014

Buying Guides

What is a heat sink radiator & why should you have one?

Q: What is a heat sink radiator?

A heat sink radiator is a radiator fitted with lockshield valves instead of thermostatic radiator valves (TRVs). It provides a path for hot water circulation when TRVs shut down.

A heat sink radiator with lockshield valves protects your boiler and system when thermostatic valves shut down. Below explains what it is, why you need one, typical locations, and suitable product options.

Key points:

Heat sink radiator uses lockshield valves, not TRVs.
Prevents boiler overheating and excessive system water temperature.
Bathroom is a common location due to frequent towel‑drying use.
Heated towel rails (chrome/white/black/stainless) make practical heat sink choices.

What is a heat sink radiator?

When planning your central heating system, an often under-discussed element is the necessity of having what is known as a ‘heat sink’ radiator.

A heat sink radiator is a rad you have in your heating system that has regular lockshield valves on it, rather than thermostatic radiator valves.

Why should you have one?

You have a heat sink radiator to stop the boiler from overheating if all the thermostatic radiator valves on the heating system shut down. It also stops hot water in your system from becoming too hot.

Thermostatic radiator valves (TRVs) are automatic so they will shut down on their own. If they all shut down and you don’t have a bypass, then the boiler has nowhere to get rid of it’s heat. So you need to have a heat sink radiator that has just lockshields on it and that will allow the boiler to circulate hot water through that radiator and get rid of the heat.

Where is it commonly placed?

The most common place to have a heat sink rad is in the bathroom. The reason fo this is because you are most likely to leave a bathroom radiator (or heated towel rail) on all the time to dry off your wet towels, so it makes sense to have one there.

Heat sink radiator product options

Bearing all that in mind, if you do need to install a heat sink radiator, you'll find some excellent heat sink candidates in our Heated Towel Rail section. We have a choice of the standard ladder type rails in chrome, white and black and we also offer stainless steel rails with a whopping 25 year guarantee. We've also got a great range of designer and traditional rails which will be perfect as heat sink rads, whether your prefer the contemporary or old school look. Dry your towels and heat your room at the same time, all the while preventing your boiler from overheating!

Don't forget to check our clearance section too for great deals on Delonghi radiators and heated towel rails

The radiator featured in the main image is the 1200x500mm Pagnani Contemporary Chrome Heated Towel Rail.

Article by Benjamin Clarke

Shop Heated Towel Rails

See Clearance Deals