Thanks for the feedback WWM. The CSV can only deliver constant pressure when the pump is running. When the pump is off, the tank delivers the flow and pressure. It is the long term uses such as watering the lawn or filling the pool that causes excessive cycling. In these cases a pump with a standard pressure tank setup may cycle every 2 minutes, which is 30 times an hour, 720 times per day, 262,800 times per year, and so on. This is where the cycling becomes destructive and shortens the life of the pump and system. All this cycling goes away with the use of a Cycle Stop Valve, and the pump system will last many times longer.
A pressure tank only system may only cycle about 3 times while showering or washing cloths. This does not cause enough cycling to be destructive, but the continuous 40 to 60, 60 to 40 cycling can be aggravating in the shower, and can cause tankless water heaters not to stay on as they should. For showers and laundry, the CSV makes the washing machine fill faster, delivers enjoyable constant pressure for showers, and keeps an instant water heater working because of the steady flow.
For intermittent uses of water such as flushing toilets, ice makers, washing toothbrushes, etc., utilizing the water in a pressure tank is a good thing. All 9.3 gallons in your pressure tank can be utilized before the pump must start. This allows you to flush about 5 times, or the ice maker to work for a month before the pump must start. Of course you will see the pressure drop from 60 to 40 as the water in the tank is used, which is the only way you can get water from a pressure tank. Once the tank is empty and the pump has started, the CSV will hold your system at 57 PSI as long as water is being used.
Narrowing the bandwidth of the pressure tank or using a much smaller tank can reduce the time waiting for the pump to start. Although the more narrow the pressure switch bandwidth or the smaller the tank, the more often the pump must run for intermittent uses such as toilets and ice makers. Even with a 4.4 gallon size tank that only holds 1 gallon of water, you get to use the whole gallon before the pump starts, which helps with toothbrush washing and ice makers. With a small tank like this, the pressure drop from 60 to 40 happens before you get the temperature adjusted in the shower, and you never notice anything but "constant pressure". With a larger tank, you may notice a drop in shower pressure when you first start but, the pressure will become constant as soon as the pump starts.
Not being able to utilize any water from a pressure tank is one of the many downfalls of the so called "constant pressure pumps" (VFD), or "tankless" controls such as the Davey or Masscontrol. When a pump system is set to maintain exactly 50 PSI all the time, you never put any water in a tank or get any out. This means that the pump must start every time you wash a toothbrush, no matter how large of a pressure tank you have. It also means that a small leak such as a slowly dripping faucet or a toilet running that you can't see, will cause the pump to cycle many thousands of times. Some of these "tankless" or "constant pressure pumps" have about an 8 second delay built in. So a slight drip anywhere can cause the pump to cycle every 8 seconds, 24 hours a day, which is 8,550 cycles per day, or over 3 million cycles per year, which a pump can never survive.
Conclusion; Constant pressure for long term uses of water is a good thing. Being able to utilize the water in a pressure tank for short term uses of water is a good thing. The Cycle Stop Valve is the only "constant pressure" device that delivers both. This is only one of the many reasons why Cycle Stop Valves are superior to "constant pressure pumps", VFD's, or any of the "tankless" controls that are available.
