Hi. I'm building a house in the mountains of Colorado and am trying to figure out how to size and set a submersible pump in my well.
First, the well is 420 ft. deep, with a static water level of 105 ft. , and produces 8 GPM (all this according to the well yield test). Other relevant details are: The house is off-grid, so I'm very power conscious. I do have 220V available to run the pump. Also, I need 75 PSI of pressure (min) at the inlet filter to the house.
I've decided (I think) that I'd like to use a Grundfos 10SQ15-330 pump, mostly because it's the only brand I can find that has a 'soft-start' feature, which will benefit my power system. Anyone know of another brand with this feature? I think the Grundfos model will produce enough pressure and flow, but that's where my questions begin.
1) The above pump has an outlet size of 1.25", but I'm told that 1" poly pipe is 'standard' for running to homes from wells. If this is the case then I'll have to adapt it down to 1", which I'm assuming will have some effect on the flow rates and pressures the pump can supply. Is this correct?
2) I realize that if my static water level is 105 ft, and I'm pumping at or below the well yield, I'm only pumping the water 105 ft. (even if my pump is set deeper). The house pressure is equivaltent to (75psi * 2.31) = 173 ft. of head, which gives me a total head of 105 + 173 = 278 ft. . According to the Grundfos pump curve the above model should deliver approx 13 GPM under these conditions, which is more than enough. Am I approaching this correctly? If so, then the next question ...
3) If I mount the pump at a depth of 410 ft in the well (10 ft from the bottom) and the static water level drops to 410 ft., then I'm pumping the water the entire 410 ft.. Add this 410 ft. to the 173 ft. of head required at the house and I get 583 ft. of head required by the pump. The pump will not supply this. According to the curve the pump will produce aprox. 9 GPM at 420 ft. of head, dropping to 2 GPM at 500 ft of head. I think this means I'll still get water from the well, just at really low pressure. Is this correct? If so, should I mount the pump at the bottom of the well, or only as deep as the pump will produce the required pressure and flow?
4) Speaking of pressure, in case #2 above where the pump is working properly, I calculate the pressure output by the pump to be approx. 120 PSI (278 / 2.31). Some of the poly pipe I've run into has a pressure rating of 100 PSI. Does this mean the pipe will burst under these operating conditions? If so, in case #3 above, the pump will be outputting over 250 PSI to get the water out of the well. Do I need to find poly pipe with a pressure rating beyond this? Does this exist? Is my well just too deep to use poly pipe?
I realize I could pay someone to do this and forget about it. However, I'm a curious DIY'er and I'd like to give it a shot. Any help you can provide would be appreciated.
First, the well is 420 ft. deep, with a static water level of 105 ft. , and produces 8 GPM (all this according to the well yield test). Other relevant details are: The house is off-grid, so I'm very power conscious. I do have 220V available to run the pump. Also, I need 75 PSI of pressure (min) at the inlet filter to the house.
I've decided (I think) that I'd like to use a Grundfos 10SQ15-330 pump, mostly because it's the only brand I can find that has a 'soft-start' feature, which will benefit my power system. Anyone know of another brand with this feature? I think the Grundfos model will produce enough pressure and flow, but that's where my questions begin.
1) The above pump has an outlet size of 1.25", but I'm told that 1" poly pipe is 'standard' for running to homes from wells. If this is the case then I'll have to adapt it down to 1", which I'm assuming will have some effect on the flow rates and pressures the pump can supply. Is this correct?
2) I realize that if my static water level is 105 ft, and I'm pumping at or below the well yield, I'm only pumping the water 105 ft. (even if my pump is set deeper). The house pressure is equivaltent to (75psi * 2.31) = 173 ft. of head, which gives me a total head of 105 + 173 = 278 ft. . According to the Grundfos pump curve the above model should deliver approx 13 GPM under these conditions, which is more than enough. Am I approaching this correctly? If so, then the next question ...
3) If I mount the pump at a depth of 410 ft in the well (10 ft from the bottom) and the static water level drops to 410 ft., then I'm pumping the water the entire 410 ft.. Add this 410 ft. to the 173 ft. of head required at the house and I get 583 ft. of head required by the pump. The pump will not supply this. According to the curve the pump will produce aprox. 9 GPM at 420 ft. of head, dropping to 2 GPM at 500 ft of head. I think this means I'll still get water from the well, just at really low pressure. Is this correct? If so, should I mount the pump at the bottom of the well, or only as deep as the pump will produce the required pressure and flow?
4) Speaking of pressure, in case #2 above where the pump is working properly, I calculate the pressure output by the pump to be approx. 120 PSI (278 / 2.31). Some of the poly pipe I've run into has a pressure rating of 100 PSI. Does this mean the pipe will burst under these operating conditions? If so, in case #3 above, the pump will be outputting over 250 PSI to get the water out of the well. Do I need to find poly pipe with a pressure rating beyond this? Does this exist? Is my well just too deep to use poly pipe?
I realize I could pay someone to do this and forget about it. However, I'm a curious DIY'er and I'd like to give it a shot. Any help you can provide would be appreciated.