Shower pump cutting out.

[wmg100]

I've fitted a shower pump to my hot supply only. The cold is mains fed but both hot and cold go through a pressure equlising valve before the bath taps. The shower just comes off the bath taps.

The shower works fine for about 30 seconds but then the pump switches off leaving you with just cold water coming out of the shower. Any ideas why this is happening as it seems very odd that the pump wouldn't come on when the hot tap is fully open. Would a more sophisticated mixer solve it rather than adjusting the temperature using the two taps?

Also any tips one making it quieter would be welcome.

Cheers,

Bill

 

[Fluffster]

I take it you are using a single impeller pump not one designed for ahot and cold feeds.
Pete

 

[wmg100]

Yep, single impeller.

 

[wmg100]

Any ideas?

 

[giblets]

I'm intrigued by the pressure equalising valve on both services. Normally this would be fitted on the cold only to reduce the pressure down to that of the hot. Sounds like a back pressure may be turning the pump off. Have you checked the actual temperature of the hot water against the pump maker's spec? Booster pumps don't take too kindly to too hot water particularly single stage ones that are designed for a mixed water temperature.

 

[Softus]

What's the inlet of the pump connected to?

 

[wmg100]

the pump is in the airing cupboard and is pumping the hot water for the whole house from the first outlet from the cylinder. It works perfectly on all of the single taps, its just the shower that cuts it out when mixing with the cold.

The equalising valve is one of these: http://www.plumbworld.co.uk/344-0000

The water temp is fine for use with the pump.

 

[Softus]

OK - that valve has a minimum inlet pressure of 20kPa == 0.2 bar.

Do you have enough head for this? It means that the base of your cold storage cistern needs to be a minimum of 2 metres above your shower head, and that's not allowing for any reduction in dynamic pressure resulting from going through the cylinder, and outlet flange you have, and pipework and bends.

If pressure isn't the problem then I'd suspect the equalising valve.

 

[wmg100]

OK - that valve has a minimum inlet pressure of 20kPa == 0.2 bar.

Do you have enough head for this? It means that the base of your cold storage cistern needs to be a minimum of 2 metres above your shower head, and that's not allowing for any reduction in dynamic pressure resulting from going through the cylinder, and outlet flange you have, and pipework and bends.

If pressure isn't the problem then I'd suspect the equalising valve.

I think it must be the valve.

Might take it out and just put a pressure reducing one on the cold and maybe move the pump to under the bath so that it's only pumping the shower.