cheap shower pump fitted away from hot water cyliner

[toadhall]

Hi
Can anyone tell me on a cheap brand of shower pump that you can fit near the shower rather than (miles away) in the basement. My shower is on the top floor at same level as water tank and my cylinder is in the basement so I suppose the 'pump' needs to suck rather than pump. I just need one shower pumped and nothing else.

Also, what on earth is the difference between postive and negative head when it comes to pumps? tks t

 

[muggles]

You can't fit a pump near your shower, it needs to go by your cylinder, unless it has a dedicated supply from the cylinder to the shower in which case you can sometimes get away with it, but at the same time if you have those dedicated supplies then there's no reason why you can't pump in the cylinder cupboard. If you try to pump off a common supply and someone opens a tap, it'll most probably suck air into the system through the tap, and air+pump=broken pump.

 

[Technotim]

Also, what on earth is the difference between postive and negative head when it comes to pumps? tks t

Positive is when you have enough flow to activate a pump say 1 liter per minute and negative is when you got jack S#@t flow that can't even turn the pump on.

Most pump manufacturers say that if you have 600mm of head (distance between the bottom of the cold water tank and the device (shower head) then it is positive head, this does not always follow though it is really the flow that matters.

 

[toadhall]

thanks Technotim,

out of interest, how the hell does the negative head pump 'know' the tap/shower has been turned on and it needs to start pumping? If the shower head/tap is above the water tank i.e. there is no natural gravitational pressure, there will be zero natural flow and turning on a tap will do sweet FA.

i ask because I have another pump supplying a loft sink that does not work when i turn the taps on. The tap has negative head for sure. The pump used to work fine but now to get the pump going, I have to suck on the tap. Is the pump knackered or has something changed in the water pressure to make the pump behave like this?

 

[Technotim]

They use a pressure vessel that stores a small charge of water pressure, so when an outlet is turned on you get a small boost of water then the pressure drops and it is that pressure drop that activates the pump.

To answer the second part of your question I would have to know which product it is, if it is a Salamander then it is not faulty it is because it is not in negative head mode (see commissioning instructions the came with pump).

 

[toadhall]

its a monsoon 1.5bar pump.

 

[Technotim]

If it has a pressure vessel, try adding a bit of pressure with a bicycle pump.
or call Stuart turner they are quite good over the phone at identifying faults.

http://www.stuart-turner.co.uk/contact-us