Considering mixer shower on second floor - options?

[dormermike]

Hi there

Living in a dormer bungalow, main bathroom is on ground floor with a mixer shower (has a pump which isnt working - flow is good without pump).

The upstairs bathroom has an broken 8kw electric shower which is supplied by a 6mm cable. I am loathed to put a new cable in if I can have a mixer shower upstairs too, with a reasonable flow.

The "airing cupboard" is next to the upstairs shower room - this contains a water tank and a HW cylinder. The header tank (water tank) would be at a similar level to the shower head.

I realise the flow would be poor - but is this where a negative head pump comes in? I did have an RGI in for a seperate issue and he took one look and said no, wouldn't work - but I can't see why not and didn't have time to discuss with him in detail.

The other question would be, is a 140l hot water cylinder big enough, i suspect not. I do not know the size of the water tank but can get dimensions if needed. I am considering upgrading this to a dual coil cylinder at some point.

Apologies for the rough drawing, but hopefully it sheds some light on my ramblings:

Second Floor Mixer Shower

• dormermike
• 18 May 2012
• 1

I had assumed a neg head pump somewhere along the bottom run would be needed?

House occupied by 2 adults and 1 female toddler and a baby girl. Am forward planning somewhat, considering that at some point it will be me and three females, so two decent showers would be good. Electric does of course provide backup etc. I did also consider a cheap 8kw replacement shower may be an incentive not to spend ages in the bathroom

Thanks
Mike

 

[Tibbot]

It's your cold water storage that may be undersized. If replacing the cylinder you could buy a vented one with an additional built-in shower coil for mains HW. If you have electric shower now, it's main can be used for the mixers cold side.

 

[Charnwood]

Unless you're a yank the title should say first floor.

Your diagram shows little or no head between the height of the tank and the shower head, therefore no pressure. It won't work.

 

[SimonH2]

Your diagram shows little or no head between the height of the tank and the shower head, therefore no pressure. It won't work.

Err, surely with a suitable pump, installed correctly, the lack of head is no problem ? There may not be enough head to start the pump, but that can be fixed with a manual start button - not elegant, but can be done.
As Tibbot says, header capacity may be an issue.

 

[dormermike]

Thanks everyone.

Apologies for naming the drawing incorrectly, not American but have lived all over and forget where I am sometimes

Don't like the sound of having to start it manually, unless its just a button... Not a footpump or something lol.

Cheers

 

[dormermike]

Regarding header tank size, I can't see any labelling on it so I guess I would have to measure it. My drawing is not to scale.

 

[SimonH2]

Don't like the sound of having to start it manually, unless its just a button... Not a footpump or something lol.

It's just a pushbutton. There was one in the shower cubicle I helped my mate pull out of his new pad last year.

Pushbutton on panel next to shower, linked with a thin plastic tube to a pressure switch in the pump. In his case, there was head (ground floor bathroom in a bungalow, header tank in loft), but I guess they found there wasn't enough flow to trigger the switches in the pump.
Operation would be : turn on shower, press button. Once the pump starts, the flow switches take over and the pump will run until you turn the shower off - then it will switch off itself.

AFAIK that's all a "negative head" pump is - same as any other pump but with the manual start built in. It still needs a positive head at the inlet to the pump, but the shower can be above the header tank.

 

[Charnwood]

Err, surely with a suitable pump, installed correctly, the lack of head is no problem ?

Missed the part about fitting a pump, just looked at the diagram.

 

[picasso]

I would consider going for an unvented cylinder, the cost of a twin coil cylinder, new pump and pipework would make an unvented cylinder cost effective (if the mains flow and pressure are good enough).