Warm thermostatic shower valve

[Mark Scott]

I've a Hansgrohe Ecostat thermostatic shower valve in my bathroom, horizontal style like in the picture here:

was fitted professionally about 5 years ago. Recently I noticed that the body of the valve is constantly warm to the touch. There are no signs of any leakage. The feeds to the valve come via plastic pipes from a shower pump next to the hot cylinder, which is in a cupboard next to the bathroom. Bit of a puzzle to me. I wonder if I should be worrying about this -- is it sinister or potentially expensive?

[Wingedcat]

If the shower valve is "constantly warm" then surely it is being subjected to a constant flow of warm water. Therefore it follows there must be a leak.

How are the pipes connected at the back of the unit? Is it in a solid wall or stud partition? Most likely source of a leak is where the feed pipes adjoin the unit, and there will be a *very* small leak hidden away in the wall cavity. Plenty to keep the unit warm, but maybe not noticeable until the ceiling falls down downstairs(!)

Easiest way to check is to turn off the hot feed from the pipe and see if the problem disappears.

[Ed Sirett]

This can be caused by a slight difference in supply pressures, there are usually non-return valves fitted in the mixer to stop this effect.

You may have to add some to the supply pipes to fix the problem.