Which CSV to Buy? - Here are My Specs

[Cary Austin]

NO.  I am saying the CSV is prior to the pressure tank/pressure relief/pressure switch, and the CSV reduces the pressure from 60-230 PSI to the 50 PSI constant that the house needs.  When you are only using 1 GPM, the CSV makes the pump think it is in a 530' deep well (230 PSI) so it can only pump 1 GPM.  Then when you use 5 GPM the CSV makes the pump think the well got shallow, 138' deep (60 PSI) so it can pump 5 GPM as needed.

If this were a 10, 15, or 25 GPM pump the CSV would be more important.  But it is hard to make a 5 GPM pump cycle because the house will use close to 5 GPM, and with a fair size tank the number of cycles is very low.  When you have a 15-25 GPM pump and the house is only using 2-5 GPM, the extra water the pump produces causes a lot of cycling, and the CSV can help with that.  With a 5 GPM pump there isn't much or any extra water to cause cycling.

[WellSaid]

Okay, so are you saying the cycling benefit of a csv would not apply since my pump doesn't cycle much anyway? If so, in my case, are the benefits of using multiple csv's just being able to eliminate a tank on the floor and having constant water pressure?

[Cary Austin]

Yes the double CSV's would let you use a much smaller tank. But even with two CSV's you would only see constant pressure when using between 2 and 5 GPM.  Using less than 2 GPM and the pressure will go up to the pressure switch shut off point.  Using more than 5 GPM the pressure will drop because that is all the pump can produce.  You would get constant pressure for a 3-4 GPM shower, but that all the pump can produce before the pressure starts dropping off.  If you even had a 10 GPM pump the CSV would be a lot more beneficial.

[WellSaid]

Is a 10gpm pump an option for my well specs?

[Cary Austin]

That depends on how much water you need.  With static at 33' you can set a 10 GPM, 1HP at about 300'.  That would give you about 400 gallons stored in the well to use as fast as needed.  So a 10 GPM pump could deliver 10 GPM for 40 minutes.  And with a CSV it could deliver 5 GPM for 80 minutes, or 3 GPM for over 2 hours at a time.  If you use more water than that, you would need to set a bigger pump at a deeper depth.  But for a house that uses the average 300 gallons or so per day, that would work great.  The 10 GPM, 1HP would only have 150 PSI back pressure so the standard PK1A kit would be all you need.

[WellSaid]

Since my water rate is at 1.46 gpm, would the 10gpm pump still work? Currently the 5gpm/1hp pump is at 450'.

[Cary Austin]

You have 1.5 gallons of water stored in the well below the static level of 33'.  So setting the pump at 300' would give you 400 gallons to use before the 1.46 gallon recharge rate comes into the picture.  Once you use the first 400 gallons at 10 GPM or whatever rate you want, then you would only get 1.46 after that.  After you use 200-400 gallons at any one time, you would just have to wait 2-4 hours for the well to recharge at 1.46 GPM before you can use another 200-400 gallons at 10 GPM.

If the pump in the well at 500' is still working, you can use it to do a draw down test.  Just run the pump wide open at 8 GPM or so for maybe an hour (480 gallons).  Then shut the pump off and see how long it takes for the water level to return to 33'.  Say that takes 4 hours to return to 33'.  It should take about 5-6 hours.  Which means you don't have to set the pump any deeper than 300' as long as you don't use more than 480 gallons every 6 hours.

[WellSaid]

When the well was drilled in 1989, they did a draw down test for 6 hours and the draw down water level was 145. Is this data still applicable today?

[Cary Austin]

Probably hasn't changed much.  Those are good numbers but it would be nice to know the flow rate of the test pump?

[WellSaid]

Would there be any disadvantage of setting the 10gpm pump at the same depth as the current 5gpm pump (450 feet)? Also, the recommended range of the 10gpm pump is 3-16gpm. Does that mean it is bad for the pump if my yield is only 1.46 gpm?

[Cary Austin]

Actually the safe pumping range for a 10 GPM pump is from 1 to 16 GPM.  But just because the well has a recovery rate of 1.46 GPM doesn't mean the pump can only get 1.46 GPM.  Like I said the pump will be able to pump from 1 to 16 GPM as long as there is a reservoir of water standing in the well.  When you pump long and hard enough to draw all the 700 gallons stored in the well, then the well will only make 1.46 GPM.  But you can pump 16 GPM until the water level is pulled down.

You can set a 10 GPM, 1HP as deep as you want, but it will only lift from about 300' and still build 50 PSI the house needs.  It will just start losing pressure if the water level gets below 300'.  And if the water level gets drawn down to 400', the 1HP will no longer be able to pump anything.

If you think you need more than 400 gallons storage to use at any one time, you will need to use a 10 GPM. 1.5 HP, which can still draw water from about 500' deep.  Most houses only use about 300 gallons in an entire day, so I don't think you need any larger than a 1HP or a setting any deeper than 300'.

[WellSaid]

Okay, so it sounds like when my current pump fails, I should go with a 1HP 10gpm pump and then I can use just 1 CSV. With my current pump, I can either go with 2 CSV's and/or a 44 gallon pressure tank. Do I have that right?

[Cary Austin]

That is correct.  And if you decide to go with the 44 gallon tank now, you can still use it with one or two CSV's later if you want.

[WellSaid]

Okay. Do sediment and iron filters go before or after the CSV's?

[Cary Austin]

It would be nice to filter the stuff before it gets to the CSV.  But if the filters are not rated for the 150-230 PSI pressure that will be before the CSV, you will need to put them after, and just let the CSV deal with the sediment.