flush valve vs Cistern flush for toilet

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Joined: June 1st, 2018, 6:24 pm

flush valve vs Cistern flush for toilet

Post by Visualizer »


I have 2 floors and total 5 bathrooms overhead tank will be at 10-12 feet height from rooftop (on staircase room). So on an average for first floor tap points the water head will be 10 + 5 = 15 feet meaning 15x0.443 = 6.5 PSI pressure.

My architect is suggesting flush valve in toilets instead of concealed cistern.
And for this a flush line of 1.5 inch will run from OHT to toilets.
Plumber is against it and suggests cisterns with 1 inch flush line and says 2 inch line is needed for flush valve.

Now i read up on net from foreign sites mostly and found atleast 20psi water pressure is needed for flush valve.
However these sites also say normal water pressure should be 40-80 PSI which looks impossible in Indian homes with 1 or 2 floors and Tank at 8-10 feet above roof.

So can anyone with practical experience suggest what will be a better option in terms of usability and maintenance.
Pressure pumps seems to br hot favorite of architects these days but
I don't want to add any pressure pump for flush line and if possible anywhere else as well.
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Joined: June 20th, 2009, 2:12 pm

Re: flush valve vs Cistern flush for toilet

Post by ardesarchitects »

I personally recommend a cistern tank ( with two settings- half flush and full flush) instead of flush valve. The pressure from 15' ht is not good enough to flush the soil easily. There is lots of water wasted in the flush valve as the user will keep it holding till the soil gets flushed. Western countries have pressurised soil lines that sucks the soil faster (not as much pressure as flight toilets), that's why they throw the tissue paper into the commodes only.  
Using a pressure pump to build pressure for flush line is not at all suggested in a residential building as it's not economical unless the usage is high.
Pressure pump is recommended for showers and concealed diverters to get pleasurable bathing experience. If we are looKing at normal fittings and bathing using bucket water then there is no need for a pressure pump at all.
Make sure you have dedicated water line even for cistern tanks to make sure later adding a pressure pump to your showers is possible.

Ardes Architects and Interior designers
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