Negative or positive head shower pump?

[R1CKY]

Hi guys, a little advice if you please! I got called to a job today to look at a shower pump that had died. It was a small salamander unit that looks as if one of the impeller housings has overheated and blistered, causing a leak.

The shower pump is in the loft, above the shower head and about 30cm below the cold water storage cistern. Pump has a minimum static pressure of 0.6 Metres and obviously it only has 0.3 Metres static head, will this have caused the damage to the pump housing?

I know Negative head usually refers to the shower outlet being higher than the cistern, but would a negative head pump be required in this instance?

 

[moony]

negative head doesnt necessarily have to be above the cwsc - it can be within 2 foot of it too - i have one now i am having to change due to head being level with bottom of the cistern

 

[R1CKY]

Just spoke to Salamander technical and there is no way around the lack of head between the pump and cistern. Plan is now to replace an additional pump in the airing cupboard with a 3bar and run the two showers from this.

The pipework will be going level with the cistern, so a negative head pump will be required I take it?

 

[neily01]

Sounds like a negative required but salamander do a descent 3bar pump for neg or pos head. Just select which mode they suggest negative head mode if it is close. Just has a little vessel on the side that sensorsany water movement.