Thursday, November 20, 2014
Some days I'm a plumber
The thing about off grid systems is that they all work together. That means that when one particular system isn't right, the whole system suffers.
Something was wrong with my water supply system. The house gets its water from a well. There's a submersible pump in the well that feeds into a pressure tank in the basement. When water is used the pressure in the system drops until a pressure switch clicks on. The pump runs, topping off the pressure tank. When the pressure reaches it's high setting, the pump shuts off again. The system is simple enough as far as these things go.
The problem is that the pump was cycling very quickly. That puts excessive wear on the pump and causes the pipes to bang. Motors draw a lot of power when they first start up. With the pump constantly turning off and on, it was always working in the most inefficient way possible. Because the pump is supplied from solar electric, the batteries drained down much quicker than normal.
My first guess what that the pressure switch might have been failing. There's a flexible diaphragm in the switch and it can get damaged. I've had to change those in the past. It was a bad guess. Fortunately, before messing with the switch I checked the air pressure in the tank. Air in the tank is compressed when the pump fills it with water. It's that compressed air that allows water to be pushed out of the tank without the pump having to start up. My tank had very low air pressure.
The solution was to drain all the water of the tank and pump up the air pressure where it belongs. Here's the funny thing, the pressure tank sits about 8 feet away from a heavy duty air compressor. The problem is that the air hose doesn't go in the basement but runs to the outside of the house near the driveway. There was once a short hose that I could have used in the basement, but it broke was never replaced.
I did not want to drive all the way into town and spend money on a hose I'd only use once in a great while. I had a little cheapo 12 volt air pump normally kept in car. The house battery bank was close enough to tap power of it to run the little compressor. Once pressure in the tank was restored the whole system once again worked the way it was supposed to.