If there is a need for emergency water during a power out condition, a standard pressure tank or water tower can also be used with a CSV system. The Cycle Stop Valve controls will see this tank as a load or demand and tries to keep it full by maintaining it at the highest pressure or level. This can be of great value during a power out condition. Knowing that your pressure tank or water tower was at its fullest level when the power went off, gives you the maximum amount of water available for emergency situations. This type system needs at least two pumps. A small pump is used for low flow conditions and keeps the pressure tank or elevated tank at its highest level. A larger pump that is capable of keeping up with peak demands is used when the small pump is unable to keep up. When the level of the elevated tank drops a small amount or pressure in a pressure tank drops slightly, the larger pump is started.
Another example using a single large pump can be set up as follows. A 2,000 GPM 100 HP water well is our only source of water. Use a 5,000 gallon pressure tank with 600 gallons of draw down and a Cycle Stop Valve on the 100 HP pump. A bypass line with a ball valve is plumbed around the Cycle Stop Valve. This bypass with ball valve will set the minimum flow produced by the pump. The pump will be turned on at 50 PSI and off at 70 PSI. The Cycle Stop Valve will be adjusted to 65 PSI and the bypass ball valve will allow 50 GPM to go around the Cycle Stop Valve. When there is a minimum usage of 10 GPM the 600 Gallons in the pressure tank will be used up in one hour. When the pressure lowers to 50 PSI the pump is started. The first 450 gallons to enter the tank will be at the maximum rate the pump can produce, less the 10 GPM that is being used at the time. Then the pressure will be at 65 PSI, the Cycle Stop Valve will shut down and only the 50 GPM bypassing the Cycle Stop Valve will be allowed into the pressure tank. The last 150 gallons needed to fill the pressure tank will enter at the bypass rate of 50 GPM, less the 10 GPM being used at the time. A little over three minutes later the pressure will be at 70 PSI and the pump will be shut off for another hour. Anytime the usage rate is above 50 GPM the Cycle Stop Valve will throttle the pump to maintain 65 PSI. This allows you to use the draw down in a pressure tank for low flow conditions and still have the variable flow advantages of the Cycle Stop Valve system when flow exceeds 50 GPM. Flow rates above 50 GPM will keep the pump running and the pressure constant. Flow rates below 50 GPM will cause the pump to cycle slowly using the draw down from the tank. This also allows you to use a 5,000 gallon pressure tank in place of a much larger pressure tank.