I looked at those things as well. 480’ is max for that size wire with a 1.5 HP pump. But I agree with LL that, “the longest length of the smallest wire permissible will deliver a reduced voltage soft start”. So I would rather use 500’ of #10 wire than to step up to #8 and loose the soft start.
I also agree with VA that the smaller pump will have less upthrust. But the 1 HP pump would only pump 50 PSI and about 5 GPM from 275’. That will reduce the stored water available from 600 gallons to 345 gallons. This still maybe enough to supply the house, but as the well production decreases over time, many people have to lower the pump at a later date. So I like to start off that way and not have to lower things later.
A CSV can eliminate upthrust. You just need to use a small tank, like the 4.5 gallon size, and set the CSV the same as the start up pressure. That way as long as you don’t open up more water than say 10 GPM, the CSV acts like a 10 GPM Dole valve and holds enough backpressure on the pump to prevent upthrust.
However, with the 1.5 HP pump, static of 45’, and a CSV setting of 40 PSI, there will be 228 PSI backpressure and 188 PSI of differential across the CSV. To handle differential pressure that high we would use two of the CSV1A valves in series. The first CSV would be set at about 130 PSI, and the second CSV would be set at the 40 PSI needed for the house. This way both CSV’s have less than 100 PSI differential and will last a long time. The friction loss of two CSV1A valves will also help prevent upthrust at wide open flow if needed.
I also prefer the small pressure tank on weak producing wells. Many times people will use up the 345 or 600 gallons stored in the well just about the time they shut off all the faucets. Then the well pumps dry while trying to refill the 25 gallons in a large tank, because there is not 25 gallons left in the well. A low pressure safety switch will not catch this problem and the pump will melt down. With a CSV filling a small tank at 1 GPM, you won’t pump the well dry refilling the tank.
I also agree you need a Dry Well protection device. I prefer the Cycle Sensor over the Pumptec for these situations. With a CSV or a Dole valve on the pump, the amps fluctuate so much that the pumptec thinks you are out of water, just from the normal amp drop that happens when restricting the pumps flow with a valve. The Cycle Sensor can show you the lowest amps produced while the pump is restricted to 1 GPM, then you can set it just lower than that and still be protected from an actual dry well condition.
I know you would like the constant pressure from a CSV compared to the pressure constantly changing from 40 to 60 as you use water. With less than 600 gallons used per day, the difference in power consumption between a 1 HP and a 1.5 HP will be less than a couple of bucks per month.
Or you can put in a 10 GPM Dole vale to limit the upthrust and let it cycle on and off with an 80 gallon tank that holds 25 gallons of water. You will just see the pressure going up and down between 40 and 60 anytime you are using water, and you have a possibility of pumping the well dry while the large tank is refilling.