Question
I have 10 year old 18-station system, an Irritrol Total Control controller and a strange problem. When I turn on any station, it runs fine for 5 minutes then gradually loses pressure and turns off.  Can't turn on this or another station for at least several minutes.  I have a well; had a new pump installed a few months ago and have no pressure problems inside the house - even with several showers going at the same time.  Also, just changed the irrigation filter.  It has been determined that there are no leaks in the system.  Any idea what's wrong?  Only thing I can think of is some problem in the controller.  Thanks for your help.

Answer
Hey Barbara, I hope this helps. When the system is running, and the pressure starts to go down, is the pressure inside the house also low? I would suspect that the water source is not able to keep up with the amount of water that the sprinklers require. The sprinkler system is going to use alot more water that even a couple of showers running at the same time. Or I should say it probably uses more, depending on how the system was designed and installed. To tell if it is the controller, all you need to do is take a volt/ohm meter, and turn a station on(lets say station#1). Now with station #1 turned on, touch your negative lead to the common terminal in the back of the controller, and the positive lead to the field wire terminal marked #1. It should read about 24 volts. Now as the station is running, and the pressure starts to drop, see if the meter is still reading 24 volts. If your reading when the pressure drops is not 24 volts, then the problem is in the controller, if the reading is still 24 volts and the system loses pressure and does not work, then you have a problem in the water supply. You might want to think about getting a storage tank to hold water that can be pumped into the system from another pump, or get a big pressure tank installed. Not knowing how exactly the system is being fed water, it is hard for me to give you an exact solution. It does sound like your water is being depleted, and then it takes awhile for the pump to catch back up before the pressure is built up enough to run the sprinkling system. Let me know if I can be of anymore help, thanks and have a great day.