Ahhhhhhhh.....no. Physics is physics. The tank is pressurized. Pressure pushes water through the pipes. There is no such thing as drawing water. Its an archaic term that is often misused.
Ahhhhhh…..yes, physics is physics. Do you know anything about transient pressure waves? These waves are the cause of water hammer when they hit a closed valve or a dead end line. Transient pressure waves are started when the pump abruptly starts “pushing” water, or when valves are closed too rapidly. They travel down pipelines at 3,000 to 8,000 feet per second, which is several times the speed of a rifle bullet. The stronger and thicker the pipe wall, the faster these waves travel. Think Tsunami caged in a closed tube. Most people have heard this water hammer “thump” when the solenoid valve on the washing machine closes.
This Tsunami pulse wave cannot be created by “pushing” water with air. It takes positive displacement as when being pushed by water instead of air to cause this pulse. Think about hydraulic pressure being stronger than pneumatic pressure. So when the system is drawing from the tank it is “sort of” being fed by pneumatic pressure. When the pump comes on the system is being fed by hydraulic pressure, which is why it feels much stronger.
The only way air can “push” water out of the tank is after you open a faucet and draw water out of the pipe system. Opening a tap causes a cascading effect of water molecules that flows from the tap to the water source. This is kind of like pulling the slack out of a chain. The water in the tank is the car being towed. When the tap opens the “slack” is being pulled out of the waterline. Only when all the “slack” has been pulled out of the water line and the pressure lessens at the tank discharge will water start flowing from the tank. This is similar to pulling all the slack out of a chain before the car will start being towed forward. You can’t stretch water molecules much easier than you can compress them, so this cascading effect happens very quickly. But you are still drawing water from the tank. The air is only expanding with decreasing pressure to take up the space after the water leaves the tank.
At any rate though, I guarantee that any difference in his pressure using a CSV is only because he will have spent the money and wants to believe. If his tank is large enough and the tank air pressure is properly set and the pressure switch is set and operating properly a CSV will do nothing other than lighten his wallet. The problem is his piping and no amount of dicking around with add on stuff is going to alleviate that condition.
In this case the problem is with the piping. But you can compensate for pressure loss in the pipe by increasing the pressure you put into it. Using a CSV to hold the pressure constantly high is going to compensate for losses much better than when the pressure is continually bobbing up and down by 20 PSI. And there is no way to use a pressure tank only type system without the pressure bobbing up and down constantly.
The best CSV for the job will “lighten his wallet” by about $63. This is way less expensive than any other “dicking around” you could do. The CSV is only an “add on” if the original installer wasn’t educated enough to know it is the most important part of any pump system. Stronger pressure in the house isn’t something you can just “believe in” strongly enough to make it happen. Either the shower is strong enough to sting your skin or it isn’t. I guarantee that with strong enough constant pressure, the shower will sting your skin, even if the pipe is undersized.
And here's the big issue though. He said only his two showers are an issue. In the zeal to sell equipment nobody bothered to ask him what the shower valves were and how they were piped. So I guess when in doubt, slap a CSV on and hope for the best LOL The OP said most of the house pressure is fine, its the two showers that are the issue. Did anyone bother to find out anything about the shower valves or the piping too them?
There is always an upstairs shower or one place in particular where you notice low pressure in the house. I guarantee after you get the strong constant pressure from a CSV to solve the low-pressure problem in that one shower, everything else in the house will also start working like you never knew it should. Toilets and washing machines will be filling faster. Sprinklers in the yard will be shooting further. Showers in other parts of the house you thought were fine will now be amazing.
I don’t mean to hit every post with “a Cycle Stop Valve will solve that problem”, but it usually will. Cycling is the cause of most pump system failures. Everything from the wire chaffing in the well, to check valves failing, bladders in tanks breaking, or stirring up sediment in the well can all be caused by cycling. I haven’t even mentioned the things most people already know are caused by cycling like short lived capacitors, relays, switches, shafts, couplings, motors, etc, etc.
Man has been looking for a cure to the problems caused by pump cycling for as long as pressure switches have been in existence. Many people in the pump business know the CSV is the answer, know how much solving these problems could decrease their business, so they do everything in their power to discredit Cycle Stop Valves. Others in the pump business just can’t believe solving all these problems could be as easy as a simple Cycle Stop Valve. Still others think it is a sign of failure that they did not get the math right if they have to use a CSV, even though they know the math never works in real life.
Sorry for the long posts. But after 20 years of using CSV’s to solve problems, I see it as a disservice when someone tries to talk others out of such an obvious, easy, and inexpensive answer.