Stuart Turner showermate twin pump problem

[Qster]

Hello, I fitted the above pump for a customer and lately it is intermittently not kicking in. The feeds are 22mm to the flexi connectors. The cold is a separate feed but the hot is the main feed that also feeds the sink in the same bathroom as the shower and the kitchen tap directly downstairs from the bathroom. Only a small house. It said you can do this and has been working on. Any recommendations on why it is now sometimes not working?
Many thanks

 

[Johntheo5]

These are positive head pumps and require a flowrate of 1.0LPM or more from either a cold or hot tap to make either flow switch to start the pump. Is this only happening when HW only required?. A likely suspect might be a thermostatic shower which when first switched on only takes HW ininitially, maybe worth holding a container for exactly 30 secs under the shower head with it in its customery position and measure this with a one Litre container, X 2 for the flowrate in LPM.

 

[Qster]

Hi, I think it’s when they use the kitchen tap it doesn’t always kick in so the pressure is obviously restricted through the pump that’s not pumping.

 

[Johntheo5]

If I'm reading you correctly, then suggest, with that kitchen tap opened, switch on the shower, if it doesn't start, measure as above from the shower to confirm that the flowrate is < 1.0LPM.

 

[Qster]

Thank you, will do. If I remember right I did do a volume test and it was sufficient but will check again

 

[random bloke]

There are positive head and negative head (aka universal) pumps in this range. The negative head is easily distinguished because it has a cylinder on top to store pressure which, when the tap / shower is opened cause an internal pressure sensor to operate and this operates the pump’s relay to operate the motor.

Both types have a 2 reed switches mounted on the pump outlet sides of both hot and cold and the negative head type also has a pressure sensor which detects its own internal pressure loss resulting from the opening of one of the outlets. Any of these sensor types can cause a problem. In the case of either type bring a magnet close to each outlet sensor (which is marked with an arrow) and it should cause the pump to operate for as long as the magnet is close (no need to open a tap etc, just the proximity of the magnet should kick the pump into life). It’s more difficult to test the pressure sensor if you have a negative head unit but since your pump isn’t operating at all that’s not actually your problem.

If the magnet test has no effect the other possible culprits are (1) the relay mounted on the circuit board and (2) the run capacitor - if its the capacitor then the motor may ‘buzz’ instead of starting but again, the magnet test will be the device which will cause the it to buzz or not buzz!

 

[oldbuffer]

The instructions require a dedicated supply from the hot water cylinder. You are not supposed to use the existing pipework where it supplies other outlets.