Simple explanations for plumbing problems

My thermostatic radiator valve snapped off

My thermostatic radiator valve snapped off

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

Thermostatic radiator valve snapped off from the body
Thermostatic radiator valve snapped off

What are thermostatic radiator valves

Thermostatic radiator valves (abbreviated to TRVs) are designed to allow a property to have different temperatures in room depending on your preference.

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.

They come in two pieces. The shiny silver coloured metal valve holds the water from the central heating system and 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 and gets 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. However 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 so 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.

A Drayton TRV 4 TRV head. A replacement if you thermostatic radiator valve snapped off
Drayton TRV4 head

A Drayton RT212 TRV head
Drayton RT212 TRV head

Pegler / Terrier

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

A Pegler terrier TRV radiator valve.
Pegler terrier TRV head

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

A Myson TRV head that can be used to repair a snapped TRV head.
Myson TRV head
A Myson TRV head that can be used to repair a snapped TRV head.
Check the metal part of the valve matches your before replacing it.
A Myson TRV2 body and head. Check if your broken TRV matches before buying a replacement

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