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+--- Thread: UV water filter/pump set up(question) (/showthread.php?tid=3115)
UV water filter/pump set up(question) - Beachboy - 03-21-2007
The tank below the water filter pump. What size do you folks have at your home? Where I stay now on 9th Ave the house has about a 20 gallon tank. My friend suggested I get a tank way larger for my home. Bigger tank less need for the pump to kick in, and that translates to a cheaper electric bill,...right?
RE: UV water filter/pump set up(question) - sansei - 03-21-2007
Motors will typically have a startup current draw 50-100% higher than the run current, depending mostly on load but it is only for a brief period of time. The current heats the motor coils and the start torque wears the bearings. Going to a larger pressure tank probably won't save enough electricity to make it worth while. If you have to change the pressure tank because it is bad, it would be worth while getting a bigger tank because the incremental cost is not great.
Here is some information you can use to make your own judgment. Pressure tanks work by having a charge of air in the tank that is compressed by water entering the tank. The compressed air provides that water pressure when the motor is off. There are two types of pressure tanks. The cheaper ones have air in direct contact with the water and have to be re-pressurized as the air is absorbed into the water. The second type has a bladder that separates the water from the air.
Tank sizing is a function of usage. Because the pressure tank works by compressing the air, a 20 gallon tank does not have a 20 gallon draw capacity. My Well Rite catalog says that a 20 gallon tank with a 20/40lb pressure switch has a 8.1 gal draw. Macomber's Rainwater Catchment booklet suggests ~50 gal/person/day. This would imply the pump gets turned on about 6 times /person in the household /day, although as they say your mileage may vary. Not a huge number for a small household.
One suggestion is if your tank is in good shape, you can parallel another tank. A second 20 gallon tank would double your capacity and cut the number of times the motor turns on in half.
One more thing to consider. A pressure tank keeps up water pressure during power outages so life can go on all be it in the dark.