Salamander V Stuart Turner shower pump

[Ady01]

Having fitted a "Watermill PR50D" positive head shower pump 18 months ago it had an epic FAIL spraying enough water from one of the end screws holding it together to find its way into my freshly decorated kitchen below.
Eventually speaking to a guy from Grundfos (who appear to have taken Watermill over) I am told that the fail was due to the pump being situated too far (approx 9 metres) from the airing cupboard (even though the cold water tank is in the loft directly above the airing cupboard) & the pump sits on the floorboards level with the bottom of the hot water cylinder. The (Bristan Qube, thermostatically controlled) shower head is fixed approx 2 metres from the floor.
Being a mere layman I expected a positive head pump would be suitable for this application but am informed that I require a heavy duty negative head pump for this situation.
I would like to to ask:
1. is this correct ?
2. assuming it is correct, which (if any) of the following pumps would you recommend please : a Salamander Force 1.5 Bar Brass Twin End Positive and Negative Head Universal Shower Pump or a Stuart Turner Monsoon Negative 1.5 Bar Twin Shower Pump

 

[Richard C]

Shower pump impellers are designed to push water; they are not very good at pulling it. Pump manufactures mostly stipulate fitting the pump next the HW cylinder & some quote a maximum length of gravity pipe work; Salamander for instance quote a maximum gravity pre pump pipe length of 4m for 22mm & just 2m for 15mm. Moving the pump away from the gravity water supply reduces supply velocity to the pump, restricts flow, overloads the pump & can cause cavitation which will destroy the impellers/casing eventually, sometimes in a very short time.

As long as you have 1 litre/min gravity flow at the shower head (ST quote 0.6 l/min), you will not need a negative head pump. If your original positive head pump kicked in & run OK without pulsing, fitting a negative head pump will make no difference once the pump is running, it certainly won't make it any less liable to failure. How do you define “heavy duty”? If you mean higher capacity then 1.5 bar isn’t particularly great & about the minimum really; I usually advise/install 2 bar or above, depending on installation & number of showers. Installing a “heavy duty” or negative head pump will not alter the fact that 9 meters away from the gravity supply is way too far & the cause of the early demise of your pump &, as you’ve discovered, pump manufacturers will not guarantee satisfactory performance at such a distance & are unlikely to honour the pump warranty.

Regarding the pumps themselves, Salamander are good (I personally have one) but I now fit ST Monsoons; more expensive but better quality & quieter in operation; but that’s relative as they are all rather noisier than the manufacturer’s would have you believe.

 

[moggridgeplumbing]

Ditto. Go for Stuart & Turner all the time.