Pressure Tank Sizing/Replacement

Hi,
I currently have an old pressure tank that seems to be bad (pressure is intermittent and the tank is causing the well pump to continually be on while water is running). The model is a Sta-Rite Con-Aire CA120, roughly 2' tall by 2' diameter. After talking with a few people, the size that i would need varies drastically from person to person, anywhere from a 30 gallon to 120 gallon. I have 2 1/2 baths, 5 people in the house, well pump motor is a Franklin 2801084915 1 HP, 230 Volt. The sizing charts that I see online are very difficult to understand, and while shopping online for a pressure tank, its confusing that a 52 gallon tank is equivalent to a 120 gallon tank??

Just wondering what my minimum/maximum size tank I should install?

How much does the "drawdown" gpm matter?

Some people say, to be safe, go with the larger tank.....

Thanks in advance for the help.

A bad tank will cause your pump to cycle on and off rapidly while you are using water. If the pump is running continuously while water is being used, you probably have a leak or a pump problem, and not a tank problem. However, I never knew that particular tank to last very long either.

In the past, the larger the tank the better. This is no longer the case. At least for the last 15 years, I have been using a Cycle Stop Valve and a small tank instead of big tanks. Big tanks just slow down the cycling, a CSV eliminates cycling, and the tank can be very small. What most people are using now is a CSV with a tank as small as 4 gallon size to about a 20 gallon size.

Even an 80 gallon tank only holds about 25 gallons of water. Your pump has to be large enough to supply the amount of water you need. A tank is just to reduce cycling, not to store any water. So if you have a valve that eliminates cycling, you don't need a very big tank. The CSV and small tank will do things that a room full of big tanks cannot do.

See this link and let me know if you have any questions.

http://www.cyclestopvalves.com/images/psidekick-ad.jpg

Tanks!

Before the Cycle Stop Valves we used to think the larger the tank the better.

Most of the knowledgeable well drillers and pump installers today install a cycle stop valve and a small tank. This gives the home owner a constant pressure; extends the pump, pressure switch, tank life and prevents water hammer in most cases.

I see where Cycle Stop Valves Inc. www.cyclestopvalves.com have recently come up with a complete system (minus the pump) called the Pside-Kick.
Try it, it will cost you less than a new large tank and you and you're wife will love the constant (city like) pressure.