A thermostatic radiator valve snapped off is quite a common problem. As long as the valve isn’t leaking it is luckily pretty easy to fix.

What are thermostatic radiator valves?

Thermostatic radiator valves (abbreviated to TRVs) are designed to allow a property to have different temperatures in each room. This helps to save energy and give the user more control.

How do they work?

Inside the plastic head is a capsule that expands as it gets hotter. This pushes a pin down onto the metal valve closing it as the room warms up. The head can be adjusted to control the temperature of the room.

Thermostatic radiator valves come in two pieces. The shiny silver metal valve holds the water from the central heating system. The plastic head controls the valve according to the air temperature around it.

Why has my thermostatic radiator valve snapped off?

The plastic connection that holds the head onto the metal valve is fragile. They get more fragile as the plastic ages. The slightest knock can shatter the plastic and cause the valve head to fall off.

In most modern designs the head is held onto the valve with a metal screw ring.

Once the head is pushed onto the body it is secured by tightening this screw ring.

Can I change a TRV myself?

You can change them yourself. Just changing the head doesn’t involve any plumbing. There are two complications when changing a TRV head.

1. Some brands of TRV heads aren’t compatible with other brands.
2. The inner workings of the metal valve may be stuck or broken.

In general a property will have all the valves the same. If one breaks you can look at the others to assess which type it is.

Different types of TRV head

The main brands are as follows:

Drayton – They have a pin in the valve body that is quite long and has flat sides. There are several designs of head but they are all compatible with the body.

Pegler / Terrier

The valves are recognisable by the pin being flatter, wider and has slanted sides.

Myson – they have a tall thin flat sided pin in the valve much like the Drayton valves. Myson and Drayton valves aren’t compatible

If you found this confusing:

If you found this confusing. Please let us know in the comments section so we can clear things up for you. We love feedback and we are trying to make the best possible website. If you don’t understand then others don’t as well. 

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