12-27-2007, 03:02 PM
quote:
Originally posted by gtill
John, as the need for pressure would be intermittant, wouldn't an on demand pump provide the needed occasional use pressure to make everything work. Could be 110AC or 12V battery or both. Could also pump the tank. ...
The typical setup is a pressure pump and pressure tank, yes.
If you do not have a situation for gravity flow, you use a "normal" pressure tank, and some kind of pump to pressurize it.
In general bigger is better for pressure tanks since a bigger tank makes for more efficient pump use (pump doesn't come on as often) and longer pump life (pump runs a bit longer when it does come on - lots of very short runs shorten pump life).
If you are off-grid then you want to use a higher-efficiency (lower power usage) DC pump such as a flowlight booster pump ($$$ but more durable and up to 65 PSI) or shurflow diaphragm pump ($ but shorter-lived/needing more maintenace and max 45 PSI).
You can use those on-grid too, just to use less power, AC versions are available.
The "normal" AC-grid-power pumps used with pressure tanks are power hogs - the flowlight uses 1/2 to 1/3 the power, the shurflo probably a bit less.
A low-flow direct solar pumping setup to a higher tank for gravity pressure will use yet less energy, if you have the terrain or structure to get the elevation you need. And of course you'll still have pressure when you have no electrical power.
At the very least, be sure to have a gravity flow tap on your tank so you can get water out easily if power, pump or tank fails.
cheers,
John S.