Do I need a pump?

[daven1986]

Hi all, I'm installing an open vented system for my hot water (bad mains pressure rules out an unvented system) and I'm wondering if I can get away without a pump. I'm going to have 2 bathrooms run off the tank and the showers are rated for 0.1 bar. I figured if i have a 28mm pipe from the tank which then becomes 22mm to feed the hot water and showers /bath and a 15mm for the toilets and sinks, then there should be enough flow to allow 2 showers to be used (max flow of the showers is 12 litres a minute), or a shower and a sink, without the pressure dropping to a dribble.

Is my logic correct, or would I need to install a system pump to ensure consistent flow?

Thanks!

 

[Steelmasons]

Might of been useful had you of mentioned static head height.

 

[daven1986]

Ah sorry, upstairs shower around 0.1/0.15 bar, downstairs around 0.4/0.5 bar. Thanks

 

[Steelmasons]

You should be able to pizz faster.

 

[daven1986]

Thanks, maybe something like this http://www.showerpowerbooster.co.uk...ower-booster-sp2b-plus-sp2bu-3-year-warranty/ for the upstairs shower and just leave the downstairs to be gravity fed?