TRV adapter sizing

[William Westcott]

I have purchased a Drayton Wiser kit to control my heating.
Not all of the TRV valves are the right size for the drayton trv heads.

I have seen various adverts for diferent sizes of Valve/head.

Most are measured across the diameter of the thread and the length of the valve body, and are usually quoted in rounded millimetres. When I measure mine with an electronic calliper it comes out as 27.93 millimetre, so do I look for a 28mm one.

They also say M28 x 1.0, what is the significance of the 1.0

 

[RandomGrinch]

Hi,

They also say M28 x 1.0, what is the significance of the 1.0

The 1.0 refers to the 'pitch' of the thread - i.e. the distance between two adjacent ridges on the thread - in this case, the distance should be 1mm.
This is a measurement worth checking on your old TRV body.

M28 is perfect for the diameter - an M28 bolt should have an outside diameter of between 27.682 and 27.962mm!

I hope that helps!

 

[Harry Bloomfield]

They also say M28 x 1.0, what is the significance of the 1.0

The 1.0 is the thread pitch, the measurement between one thread peak and the next adjacent one which is 1mm. Count 10 and they should equal 10mm.