pump cycling-pressure tank volume-irrigation system
Posted by Steve on December 06, 2001 at 14:07:49:
I have a 1 HP submersible of about 16 gpm capacity and an plain steel pressure tank of 86 gallon capacity. It has always worked fine. Recently, I began adding a sprinkler system to the yard, and began realizing some things I had'nt thought about before. With the 86 gal tank, there is only a usable volume of about 9 gallons. I did some calculating and convinced myself that this is correct. (does this seem about right to you?) Anyway, I am concerned about excessive pump cycling, it looks like with this arrangement the pump would cycle more than 30 times per hour during irrigation (with the sprinkers running at about 9 gpm).
I've come up with an idea that is either very clever, or will lead to some kind of unforeseen disaster. I figure that if I obtain a second 86 gallon plain steel tank and connect a pipe from the top of the first tank to the top of the second tank, then the additional air volume stored in the second tank will more than triple the usable capacity of my present tank, to about 36 gallons. (Only air would be contained in the second tank) By my figures, at the pump cut-off pressure just about the entire volune of the present tank will be filled with water, and at the pump cut in pressure, the water would be about 28 inches below the top of the water tank.
Does anyone see any pitfalls in this approach? Has anyone seen an arrangement such as this?
Thanks for any feedback,

Replies to this post