Well Pump Distance and Pressure Tank Size

[Ultisol]

I posted about 18 months ago regarding low pressure in my new house. The attached diagram shows the current setup on my farm. We are now planning on wiring the pump to be connected to the new house so that it can be connected to the backup generator that way we can also maintain water to the barn and cabin should power go out. We planned for this when we built the house and already ran conduit underground with rope so we can pull the electric wire through. With this change, the pressure tank will now be in the basement in the house. The set up is currently, 1 HP - 15 GPM pump set at 130 feet deep. Well is producing 45 GPM. The elevation change from the well head at grade to the second floor in the new house is about 50'. From pump head to new house is 400 feet. 1 inch water line from well to house and well to barn/cabin.

Questions: What is the recommended pressure tank size and pressure switch size? Right now the pressure tank in the barn is 70 gallon with a 40/60 switch. I have been advised to do a 60/80 switch and 80 gallon pressure tank, but wasn't sure if that would be too much for the house or if it would be needed to overcome friction loss with the 400 feet run. It was also suggested to put a check valve at the well head. I have talked to a few local plumbers and well pump companies and get conflicting advice. Any thoughts would be appreciated. Thanks!

 

[Jadnashua]

You will lose about 0.43pounds/foot elevation increase...so, decide how much pressure you want at the highest point, and figure out your pressure required at the source (where the switch will be).

For each kind of piping material, there's a maximum flow rate recommendation. You can also look up the frictional losses in that pipe at various flow rates. The combination of frictional losses and elevation changes will guide you on what pressure will work out best for you.

You want the pressure tank sized so that you don't get frequent on/off cycles of the pump motor. So, that would depend on your typical draw at any one time.

 

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[Valveman]

50' of elevation will cost 21 PSI loss. So to get the same average 50 you get with a 40/60 switch, the 60/80 switch would be about right. At 60/80 pressure an 80 gallon tank will only hold 18 gallons of water. With multiple buildings and uses, I would use at least two of those 80 gallon size tanks. You could also use a Cycle Stop Valve, which will work with the tank you have. You really only need 44 gallon size tank with the CSV working at that pressure, and it would do a better job than a room full of large tanks. You will need to install the CSV1A at the well before the line tees in two directions. You may also want pressure reducing valve on the line going to the barn and cabin, as 70 PSI constant pressure there could be more than the floats in the water troughs can handle. The only check valve you want is the one on top of the pump. Any other check valve will cause a water hammer problem.