A little more background on my experience with the CSV. The primary reason I got my CSV was to stop the pump cycling to preserve my pump. I do not have a sprinkler system for my yard, but I do water many little trees and bushes during the summer and this process can take 1.5 - 2 hours, where the pump is cycling on and off continuously during that time period. I have a 44-gallon pressure tank, but it does not hold 44 gallons of water. It only holds around 12 gallons of water. This is the case with all different sizes of pressure tanks. They only hold around 25% of the stated size of the tank. So when watering my yard, once I've consumed 12 gallons of water, the pump turns on and fills the tanks with 12 gallons.....shuts off.....tank depletes.....tank refilled with 12 gallons, etc. etc. So, my pump would be turning on every 2 minutes or so, for 90-120 minutes. It was during one of these watering episodes that my original pump failed and also during one of these episodes when my first replacement pump failed. With the CSV, when you open one or more faucets that result in overall consumption of more than 1 gallon/minute, whatever volume of water that remains in your pressure tank is consumed first. Then the CSV opens and remains open as long as the pump is running and the consumption rate is greater than 1 gallon/minute. When you turn off the faucet, the CSV closes and your pressure tank refills.
I have a 60/40 pressure switch on my pressure tank. So, when I take a shower, if my pressure tank has......say.....5 gallons remaining in it. my shower head will be flowing at 40-45 psi.....the lower end of the pressure range of my pressure switch. Once the pressure tank is exhausted of the 5 gallons of water, the CSV opens (the CSV is set at 55 psi) and the pump turns on and starts pumping at 55 psi. Note: the pump is pumping at a much higher pressure than 55 psi, but the CSV restricts the pressure to not exceed 55 psi. So back to the shower.....the pressure tank depletes, the pump comes on, and the flow rate coming out of the shower head increases to 55 psi and you can feel the increase in flow. And that 55 psi flow rate continues the entire time I am taking a shower until I turn the shower valve off. At that point, the CSV closes, the pressure tank refills, and the pump shuts off. So the pump has not cycled on and off during this entire process, and therefore, the pump does not overheat.
You can use a CSV with a very small pressure tank, and that feature is highlighted on the CSV site. This would mean that you would have a very, very short period when the small pressure tank is feeding the water supply at the lower end of the pressure switch pressure, and basically, almost the entire time that you turn on the faucet, you would have 55 psi because the CSV would open almost immediately. I personally would be concerned about the pump cycling on and off more often because of that very small pressure tank capacity. So, for example, if you turned on the water at your kitchen sink to wash dishes, you might trigger the pump to turn on. I like the idea of having up to 12 gallons in my 44-gallon pressure tank to feed my water needs for small, incidental uses of water and not trigger the pump to come on. Note: a small use of water like washing dishes or flushing a toilet could still trigger the pump to come on if the pressure tank happens to be close to empty. When I'm in the shower, even If I have all 12 gallons in the 44-gallon pressure tank, that water is consumed quickly while I'm waiting for the water to warm up, and then, maybe the first couple of minutes while I'm in the shower. After those first couple of minutes, the full 55 psi pressure comes on and continues until I'm done in the shower. So, if I were to do it again, I would still use my 44-gallon pressure tank with the CSV. I am very happy with my CSV. It's been 3 years that I have had and it's worked flawlessly for my irrigation needs too.