Pulsating shower pump - hot water in a gravity fed system

[nickse]

The shower pump pumps cold water fine but pulses (shuts on and off repeatedly) for mixed and/or hot water.

If left on for hot water, the shower pump pulsates continuously for about 20 mins and then just stops pumping altogether, whilst gradually decreasing the frequency of the pumps.

The shower pump (Stuart Showermate 1.5bar twin) is about 4 months old and serves as a replacement for the old one which just leaked for some reason.

I have a gravity fed system with cold water and pressure tanks in the attic and the hot water tank in close proximity to the shower pump.

The problem appeared recently, it worked alright for 4 months.

Thank you.

 

[Exedon]

It's called hunting.
For a start go on Stuart Turner Web site they have a list of FAQ. that includes this problem.

 

[nickse]

It's called hunting.
For a start go on Stuart Turner Web site they have a list of FAQ. that includes this problem.

Only advice I could find is to bleed through without the pump on and it didn't work.

I am thinking about contacting them, this might be a malfunction of the pump.

 

[dilalio]

Pump is starved of flow.

 

[TimboTwo]

Debris in tank patially blocking the outlet, being pulled by pump suction?