Jan 9, 2007, 6:12 PM
Post #8 of 10
Sparks, It wouldn’t take a pressure sensitive pump, but a pressure sensitive switch to start the pump each time a faucet was opened. This type of system has been used for several decades in RVs, Motor homes, travel trailers, self-contained pickup campers etc. They are called demand water systems.
Re: [sparks] Another take on water system
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The pump will start every time any water is used, this may shorten the service life of the pump slightly, but probably by a negligible amount. The main possible disadvantage to a demand system is that when the power fails, you will have no water available until the power is restored. I would hate to be caught in the shower with my hair full of shampoo when the power fails in a house with a demand water system.
The reliability of the power supply in a given area would be a big consideration for me before I would opt for a demand water system. A modern pressure tank with a diaphragm in it would probably be a better option if higher water pressure were desired.
In a 3-story house, I don’t think I would rely on a centrifugal pump as is usually used here in Mexico for any kind of pressure on the third floor. Under ideal conditions, a centrifugal pump will only lift water 32 feet at sea level. Because of resistance in the pipes, and other factors, as a practical matter, in most instances centrifugal pump will usually only lift water an average of 27 feet. Any water lifted to the third floor by a centrifugal pump, would have practically no pressure by the time it reached that height.
A displacement pump, while slower, would be a viable alternative for lifting water any higher than 27 feet.
A tinaco on the roof would be the most reliable way to get any water pressure on the third floor if you are using a centrifugal pump. Since water produces just slightly less than ˝ pound of pressure per foot of elevation, you would probably have about 5 pounds of pressure in a third floor shower, and about 12 pounds of pressure on first floor fixtures.
I posted the formula for calculating gravity water pressure a few years ago, if you do a search you will find it.
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