what is this ? looks like a pressure meter ? wire is cut off

[Softus]

OK then. So you could just ignore this device.

Are you so sure about that, when we don't even know what it is?

It could be two small pressure vessels, mounted end to end, one off the hot side and one off the cold, but with no water connection between the two (the black bit being the housing for some sort of sensor).

But the OP has said that it's in parallel with the hot pipe that goes to the pump.

Unfortunately the OP refuses to show us enough of the installation for us to see how it functions.

Tell me about it - good luck with that one.

 

[andy007007]

sorry. the pipe from the pump goes up to the sink upstairs and this gadget is parallel about 500mm up from the pump. i will get better pictures tonight !

 

[chrishutt]

But the OP has said that it's in parallel with the hot pipe that goes to the pump.

You trust this OP's judgement on plumbing arrangements? I'll only believe what I see with my own eyes.

 

[Softus]

You trust this OP's judgement on plumbing arrangements?

OK. You got me.