The existing 20 gallon tank is right at the pressure switch so I am thinking I will be good. Thanks for the help,
I dont know why the well guys install such small tanks unless they use the CSV. I have a friend here that is just about done with building a house and I mentioned this to him. He said his tank was in the "hot rock" with the well head for his submersible 2 HP pump and he wondered why it was so small. I told him about the CSV as a way to fix the problem if they did not install one for him. I am betting they did not.
Small tanks are also installed because the pump man wants to beat the other quotes to get the job. Water still comes out the faucets so the customer doesn’t know the difference until they start researching why their pumps don’t last very long.
23 years ago I was installing CSV’s with 80 gallon tanks. 15 years ago I changed to using 20 gallon tanks with CSV’s. Many pump installers told me they had been installing CSV’s with 2.2 gallon tanks without problems for many years, so they would fit under the “hot rock”. So about 8 years ago I started installing 4.5 gallon size tanks with CSV’s.
As you can see I didn’t just make up this stuff. The small tank and CSV has been well tested and proven. Many thousands of systems have been installed with a small tank and a CSV over many years. If the small tank with a CSV was a problem, we would be hearing about a lot of failures the same way we hear about all the failures with VFD’s.
There is nothing wrong with using a large tank with a CSV. I just no longer believe a big tank has any benefit.