Q on CSV operation

Discussion in 'Pumps and Tanks Well Forum & Blog' started by ncgeo, Mar 1, 2009.

  1. ncgeo

    ncgeo In the Trades

    Messages:
    47
    Location:
    North Carolina
    I have an 86 gal bladder tank on my well eqipped with a 3/4 HP 12 GPM Meyers Predator pump, set at about 32/52 psi cut-in/cut out pressure. The well is used to operate my geothermal heat pumps only with maximum flow of 9 GPM. The drawdown on the tank is about 25 gal at those pressures, and with the heat pumps running the runs for about 3 minutes and is off for about 2-1/2 minutes. Since on the coldest nights the heat pumps run near-continuously that still seems like a a lot of cycling, so I am considering a CSV.

    If I set the CSV pressure to about 40 psi I understand that during use the tank pressure will go down to the 32 psi cut-in at which time the pump will kick-in. It will supply the 9 GPM for the heat pumps plus additional to fill the bladder tank until it reaches the 40 psi CSV set pressure. At that point the tank and CSV will be at 40 psi, and the CSV will only flow the 9 GPM while the heat pumps continue to run. When the heat pumps shut down, the CSV will reduce pump flow to 1 GPM until the tank fills reaches cut-out pressure. I figure this could be as long as 15 minutes(!) based on tank capacity.

    Does all of this sound correct? I am most concerned with the interval after the heat pumps shut down and the CSV is generating minimal flow. During that time everything between pump and CSV will see high head pressure, and with just 1 GPM flow the pump may overheat. Is it better to use a CSV with a small tank for this reason? I'd prefer not having to replace the tank.
  2. speedbump

    speedbump Previous member

    Messages:
    4,540
    Location:
    Riverview, Fl.
    Don't worry about the pump overheating. If you want the pump to shut off quicker after water usage, you can get a much smaller tank or set the shutoff pressure closer to the CSV's pressure setting. Or if you got a brass valve, you can set the CSV's pressure up just under the cut out of the switches setting.

    bob...
  3. ncgeo

    ncgeo In the Trades

    Messages:
    47
    Location:
    North Carolina
    Thanks valveman. Another question, here in NC we do not use pitless adapters (so I've been told by 2 different drillers). So the poly drop pipe is connected to a T which sits on top of the above-ground well seal. Off the side outlet of the tee is PVC elbowed down the side of casing and underground where is coupled to poly run to the house. On top of tee is spigot. Do I need to worry about the pressure when the CSV is flowing just 1 GPM? The pump curve shows a max of 310 feet of head and my pumping level is just 20 foot below the service. So I figure I'm still seeing 125 psi on the PVC which is far more than typical. I believe no valve should be between pump and CSV, so the spigot needs to go.
  4. valveman

    valveman Moderator Staff Member

    Messages:
    4,368
    Location:
    Lubbock, Texas
    If you install a CSV in the well, under the well seal, you can use the faucet. If you install the CSV after the faucet then, you need to remove or just don't use the faucet.
  5. ncgeo

    ncgeo In the Trades

    Messages:
    47
    Location:
    North Carolina
    Do you think there is any issue with 125 # on the 1" PVC?
  6. valveman

    valveman Moderator Staff Member

    Messages:
    4,368
    Location:
    Lubbock, Texas
    Nope!! Not at all!!
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