Drayton TRV4 Thermostatic Radiator Valve Head

By Drayton · Model: 07 25 006 · Plumbing & Heating

Thermostatic radiator valve head only (no valve body), with a liquid sensor, 0 to 5 settings with frost protection and an M30 x 1.5mm thread.

Liquid-filled sensor responds to room temperature
Settings from 0 (frost protection) to 5
M30 x 1.5mm thread connection
Head only: the valve body is not included
Screws onto the valve body on the M30 thread
No batteries or power supply needed

Overview

The Drayton TRV4 is a thermostatic radiator valve head. It is supplied as a head only, without a valve body, and screws onto a compatible valve body on an M30 x 1.5mm thread. A liquid-filled sensor responds to room temperature and moves the valve pin to reduce or increase the flow of hot water through the radiator. It is purely mechanical and needs no batteries or power supply.

In-Depth Look

The Drayton TRV4 is a mechanical thermostatic head for a radiator valve. It is sold as a head only, so it fits onto a valve body that is already on the radiator or bought separately.

How the Sensor Works

The TRV4 uses a liquid-filled sensor. As the room warms, the sensor expands and pushes on the valve pin to reduce the flow of hot water through the radiator. As the room cools, the pin is released and the flow increases again. There are no electronics or batteries.

Settings

The dial runs from 0, the frost protection setting, to 5. The numbers are settings rather than exact temperatures, so the room temperature for each number varies with the room and the system.

Fitting

The head screws onto the valve body on an M30 x 1.5mm thread. Check that the existing valve body uses this connection before buying. If you are unsure, ask a plumber or heating engineer.

Summary

The Drayton TRV4 is a head-only thermostatic radiator valve head with a liquid sensor, a 0 to 5 dial and an M30 connection. It suits people replacing a worn head or fitting heads to compatible valve bodies.

How It Compares

The Drayton TRV4 is a thermostatic radiator valve head. It is a sensing head only and does not include the valve body. The head screws onto a valve body with an M30 x 1.5mm thread, and it uses a liquid sensor. The scale is roughly 10 to 30 degrees C, and there is a frost protection position. It is a manual control, not a smart one.

In plain terms, the valve body sits on the radiator pipework, and the head senses the room temperature and opens or closes the flow to the radiator. If you are replacing a head, you need a valve body with a matching thread.

Option	What it is	What to weigh up
This head	Manual TRV head, liquid sensor, M30 x 1.5mm thread	Check the valve body thread matches
Smart TRV heads	Heads controlled from an app or hub	Part of a smart system
Manual lockshield valve	A valve set with a tool, not by temperature	Does not respond to the room temperature
TRV heads with other fittings	Some heads use different fittings	Check the valve body before buying
Room thermostat	A thermostat that controls the heating for a room or zone	Works differently from a head on each radiator

For a smart system with TRVs, see the Drayton Wiser multi-zone smart thermostat kit. The Honeywell V4043H zone valve 22mm is a valve that controls a whole zone rather than one radiator. Our guides on installing a radiator, bleeding a radiator and choosing central heating components are useful alongside.

Check the colour and the head type before you order, because heads and valve bodies are sold separately. The scale and the frost position are printed on the head, so you can see the setting at a glance.

Common Questions

What is the difference between a TRV head and a TRV valve body? The head senses the temperature. The body sits on the pipe. The head screws onto the body, so the two parts must match.

What does M30 x 1.5 mean? It is the thread size on the valve body. Check that it matches the head before you buy.

What do the numbers on a TRV mean? They are comfort settings, not exact temperatures. The scale covers roughly 10 to 30 degrees C, so use the numbers as a guide and adjust to suit the room.

What is the frost setting for? It keeps a little heat flowing in cold weather, so the radiator gets some warmth even when the room is not in use.

Do I need to drain the system to change a head? Generally no. The head can be changed with the valve body left in place, so the system does not normally need draining. Follow the instructions, and check before you start.

Why is part of my radiator cold when the rest is hot? That is a bleeding or sludge matter rather than a TRV one. See our guide to bleeding a radiator.

Is this a smart TRV? No. It is a manual control, set by turning the head to a number on the scale. A smart system with TRVs is a different product, and the Wiser kit linked above is one example.

Heating work should be done by a competent, qualified person if you are unsure. Follow the manufacturer’s instructions.

Specifications
Sensor Type	Liquid-filled
Temperature Range	Settings 0 (frost) to 5
Thread	M30 x 1.5mm
Frost Protection	Yes (setting 0 / asterisk)
Colour	Chrome and white (as listed)
Compatibility	Valve bodies with an M30 x 1.5mm connection
Supplied	Head only, no valve body

Who It's For

Plumbers and heating engineers fitting or replacing TRV heads
Homeowners looking to replace worn or stiff TRV heads for better room temperature control
Landlords wanting room-by-room temperature control in rental properties

Pros & Cons

Pros

No batteries or power supply needed
Liquid sensor responds to room temperature
Uses the common M30 x 1.5mm connection
Frost protection setting prevents pipes freezing in unoccupied rooms

Cons

No smart or app control, as it is purely mechanical
Valve body not included, so check the existing body before buying
Temperature markings are numbered rather than showing actual degrees

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