Minimum water pressure for Triton shower

[tadrb]

I have bought a Triton Amber 3 electric shower (8.5kW) but I am surprised to see that this has a minimum inlet pressure specification of 1 bar at 8 l/min.

This unit is to replace a Triton Ivory II (also 8.5kW) which had operated satisfactorily since 2005. Upon checking, I found that this has the same requirement. (I never checked in the first place as it was installed by a builder's plumber.)

The shower is fed by a tank almost directly overhead. The fall is 2.1m which corresponds to a pressure of only 0.206 bar. I have measured the flow rate of the Ivory II at 9.5 l/min. This flow rate is within specification which I would have thought would be the only requirement. Am I missing something here? Advice would be appreciated.

 

[sooey]

Are you sure it's fed from the tank, and not from the cold main which is feeding the tank?

 

[tadrb]

Definitely from the tank: I have isolated it using a tap on a pipe coming from (and close to) the tank.

 

[bolshy]

A pipe definitely connected to the tank, high up on the tank, or at the bottom? It could be the cold mains feed to the float valve, which means the pipe is feeding the tank, not coming from it.

 

[seco services]

There is no way that is tank fed it won't activate the pressure switch at 0.2 bar.

Some will still work as low as 0.7 bar but not 0.2 bar.
0.2 bar will just about hold the diaphragm closed when shower off.

 

[tadrb]

You are absolutely right. I had confused two pipes. The shower _is_ fed from the rising water main. Thanks. Your advice is much appreciated.