Starting to consider the water system for our lake cabin. The well is a 2″ driven sandpoint to about 50 feet. Cabin will have 2 baths, one with a whirlpool tub. Two person occupancy most days, up to 10 when the kids come. The local hardware has several pumps, one that can be wired 120 or 240.
Q. What are the considerations in wiring 120 or 240? At this point I can do either.
Q. What are the considerations for sizing a pressure tank? Is bigger just better, or is there over-design possible?
Thanks to the pros out there who have taught me so much.
Replies
Before you decide what voltage pump motor you need there are a couple other considerations. The well is about 50 ft deep, how far down is the water level, how much does it drop while pumping and how long before it returns to its original level. A shallow well jet pump won't pull water from a depth more than 23 to 25 feet, and that's pushing it. If you're pumping from deeper than that, you'll have to go with a deep well system with a packer.
You then need to figure out what the water demand in gallons per minute is going to be. The pump will have to be sized to meet the water demand in gpm from whatever depth you decide from the well. Maybe a 1/2 hp pump motor will do the job, maybe it will take a 3/4 hp.
As for sizing the pump tank, you want to have a large enough tank so from the time the pump begins running, it takes between 1 and 2 minutes to replenish the water in the tank and shut off. But if the gpm the well will supply is less than the water demand in gpm, then you'll have to oversize the tank in order to have enough water available without running out.
To answer your original question, I think the general rule of thumb is that 240V is more efficient that 120V.
I think I have some charts and other info that will help you to size the water system (pump and tank). Let me know if you're interested and I'll try to find the stuff and scan it so it'll go via e-mail.
220v is more efficient/better on the pump motor (draws half again as many amps.)
The bigger the tank, the better. (Minimizes pump cycles and allows the pump to run longer, which minimizes pump wear and tear.)
You mean "draws half" not "half again"
"220v is more efficient/better on the pump motor"
Absolutley not.
The motor don't care as long it is working at it's designed voltage.
What it boils down to is the how easy that it is to deliver the needed current without significate voltage drop.
First we need to know two things. What size motor do we need. That is determined by now much the pump has to deliver, pressure (at the pump) and flow.
The other parameter need is the length of the electric run.
All of that said there if 240 is available and the desired size of pump is available in 240 then there is no reason not to use that and it might save in wiring cost.