New Pump Sizing?

[JoeJee]

Some help if anyone can. We are experiencing substantial pressure loss when we have multiple people showering and will be adding more showers this year. Currently 4.5 showers. We will eventually have 3 dwellings plus a shop on the property. Total of 9 showers and 11 bedrooms.

Current well info that we know of based on hearsay:
Well Depth 420ish ft.
Pump depth unknown.
Estimate pump to be 1/2-3/4. Get about 10-gal/min off hydrant next to well.
Pump was changed at some point from 3-wire to a 2-wire.
Has not run dry yet nor has my neighbor's wells.
Last summer water was about 80' down.

One Local well company is suggesting a A 10ga 3 WIRE 1.5HP 10GPM PUMP at about 100' w/ 1" sch 80 pvc. They did not state a brand or model number. Other well companies have not responded to our calls yet for an estimate.

I do have a CVS and plan to keep it. Any issues with sch 80 pvc and the CVS? Any suggestions on what pumps I should request and at what depth?

Is there a gal/min regulator to make sure a dwelling doesn't go overboard and starve the others?

 

[Valveman]

A 10 GPM, 1.5HP will pump from much deeper and/or build more pressure, but won't pump any more water than the 10 GPM, 3/4HP. If all nine showers are running at the same time it would take about 25 GPM. That is not likely to happen but I would still opt for at least 20 GPM to double what you have now. A 20 GPM, 1.5HP will pump 20 GPM at 60 PSI from as deep as 160'. I am guessing setting the pump at about 200' would be fine since the water level is at 80'. But if the larger pump pulls the water level deeper than 200', an even larger pump will be needed and would need to be set even deeper.

Installing a larger pump that can run 9 showers will cause the pump to cycle on and off much more than usual when running anything less than 9 showers at a time. Adding a Cycle Stop Valve will make the pump large enough for 9 showers work just as well for only 1 shower at a time, and would allow the use of a much smaller pressure tank. You can get the PK1ALT, which has everything you need to control the pump except the tank. Then with that many dwellings and showers I would add a 20 gallon size pressure tank to the PK1A.

PK1A-LT Constant Pressure Pump Control Kit (Less Tank) – Cycle Stop Valves, Inc

Buy It! Interactive Animation Replace a big pressure tank with a Pside-Kick General Information Typical Applications Specifications Installation Instructions Troubleshooting VFD Controller Replacement WARNING: This product can expose you to chemicals including nickel, which is known to the...

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[JoeJee]

A 10 GPM, 1.5HP will pump from much deeper and/or build more pressure, but won't pump any more water than the 10 GPM, 3/4HP. If all nine showers are running at the same time it would take about 25 GPM. That is not likely to happen but I would still opt for at least 20 GPM to double what you have now. A 20 GPM, 1.5HP will pump 20 GPM at 60 PSI from as deep as 160'. I am guessing setting the pump at about 200' would be fine since the water level is at 80'. But if the larger pump pulls the water level deeper than 200', an even larger pump will be needed and would need to be set even deeper.

Installing a larger pump that can run 9 showers will cause the pump to cycle on and off much more than usual when running anything less than 9 showers at a time. Adding a Cycle Stop Valve will make the pump large enough for 9 showers work just as well for only 1 shower at a time, and would allow the use of a much smaller pressure tank. You can get the PK1ALT, which has everything you need to control the pump except the tank. Then with that many dwellings and showers I would add a 20 gallon size pressure tank to the PK1A.

PK1A-LT Constant Pressure Pump Control Kit (Less Tank) – Cycle Stop Valves, Inc

Buy It! Interactive Animation Replace a big pressure tank with a Pside-Kick General Information Typical Applications Specifications Installation Instructions Troubleshooting VFD Controller Replacement WARNING: This product can expose you to chemicals including nickel, which is known to the...

cyclestopvalves.com

Thank you for the information. I will definitely keep my current CSV despite the well companies suggestion. I am going to ask for a revised quote based on your recommendations. Would a 20 GPM 1.5 HP pump or possibly a larger one (if needed to go lower) be ok on 1” schedule 80 PVC? How low could I realistically put a pump to make sure I lower risk of running dry?

 

[Valveman]

No reason to set a 1.5HP, 20 GPM pump any deeper than 200'. If you want to go deeper a 2HP, 20 GPM pump can work from as low as 300' deep. With a local company suggesting a setting of 100', I would think the 1.5HP set at 200' should be more than sufficient. Either of those pumps will work fine on 1" Sch 80 and a CSV.

The deeper you set the pump the less cooling flow it will get. But maybe with a 420' deep well all the water is coming in from below 200'-300'. If you have 5" or larger casing I would recommend a cooling shroud or flow inducer so you don't have to worry about the cooling flow to the motor.

The larger the pump, the more important the CSV is. That pump is going to want to put out 20 GPM anytime it comes on. Without a CSV that can cause lots of cycling when using anything less than 20 GPM. The CSV will make that pump work down to as little as 1 GPM without cycling at all. If the well guys are suggesting removing the CSV you should be suspicious of any other advice they give as well, like setting the pump at 100'.