2 of 3 sprinkler zones have very low pressure. I have completely ruled out leaks and valves. The problem must be the source. At one point the system was perfectly balanced. Why would 2/3 zones have low pressure now? Something must have changed. The question is, is it the pump, pressure tank, or well? The system was not used for a little over a year. The water produced is slightly brown in color.
I have somewhat ruled out the pressure tank and pump. I inspected the tank (2.1 gallons) and re-charged it to the factory air charge of 28 PSI. The pump is a 3/4 HP jet pump rated for 10 GPM and I confirmed it pumps out 10 GPM with the 5 gallon bucket test at the faucet right off the pump numerous times consistently producing 10 GPM.
So is the well itself to blame?
Here's the part that baffles me, and I'm hoping someone knowledgeable on wells can enlighten me: Every single sprinkler head in the problematic zones have been capped off to inspect the pressure. Capped or not, the pressure at the gauge in those 2 zones behaves the same. As soon as I open the valve on one of those zones, the gauge drops to 0 and slowly builds up to 10 PSI, but no more.
Zone 3 has 3 rotating heads in the backyard. The well, pump, tank and valves are all in the backyard too. Zone 3, the working zone, maintains a constant 30 PSI, which is fine (40 would be better though...). Zone 3 does appear to be the smallest of the zones, having only 3 heads. Zone 1 has 9 spray heads, 6 on one side of the house, 3 on the other, so the piping goes all the way around the house. Zone 2 is similar in layout, with 4 rotating heads in the front yard and piping that wraps around to the front of the house. At one point all these heads worked fine with full pressure. So something changed.
So after doing lots of research online what I have come up with so far is this:
The water table may have dropped and the static head of water in the well is much less now. Zone 3 has less pipes overall so it doesn't immediately deplete the static head in the well so once it's pipes pressurize it's only the loss at the sprinkler heads that can easily keep up with the recovery rate of the well. However, zones 1 and 2, with much more piping, are emptying the static head upon pressurizing their pipes, reducing the flow of the pump from 10 GPM to the recovery rate of the well thus decreasing pressure giving me the 10 PSI reading on the gauge.
Assuming my theory is correct, I'm still baffled why capped heads don't pressurize the system. Is the pump pumping at that point just to maintain whatever little pressure it has produced? I'm confused.
If it is a lowered water table, what are some of my options to get the pressure back in my zones? Larger pressure tank? More powerful pump? Any help appreciated.
I have somewhat ruled out the pressure tank and pump. I inspected the tank (2.1 gallons) and re-charged it to the factory air charge of 28 PSI. The pump is a 3/4 HP jet pump rated for 10 GPM and I confirmed it pumps out 10 GPM with the 5 gallon bucket test at the faucet right off the pump numerous times consistently producing 10 GPM.
So is the well itself to blame?
Here's the part that baffles me, and I'm hoping someone knowledgeable on wells can enlighten me: Every single sprinkler head in the problematic zones have been capped off to inspect the pressure. Capped or not, the pressure at the gauge in those 2 zones behaves the same. As soon as I open the valve on one of those zones, the gauge drops to 0 and slowly builds up to 10 PSI, but no more.
Zone 3 has 3 rotating heads in the backyard. The well, pump, tank and valves are all in the backyard too. Zone 3, the working zone, maintains a constant 30 PSI, which is fine (40 would be better though...). Zone 3 does appear to be the smallest of the zones, having only 3 heads. Zone 1 has 9 spray heads, 6 on one side of the house, 3 on the other, so the piping goes all the way around the house. Zone 2 is similar in layout, with 4 rotating heads in the front yard and piping that wraps around to the front of the house. At one point all these heads worked fine with full pressure. So something changed.
So after doing lots of research online what I have come up with so far is this:
The water table may have dropped and the static head of water in the well is much less now. Zone 3 has less pipes overall so it doesn't immediately deplete the static head in the well so once it's pipes pressurize it's only the loss at the sprinkler heads that can easily keep up with the recovery rate of the well. However, zones 1 and 2, with much more piping, are emptying the static head upon pressurizing their pipes, reducing the flow of the pump from 10 GPM to the recovery rate of the well thus decreasing pressure giving me the 10 PSI reading on the gauge.
Assuming my theory is correct, I'm still baffled why capped heads don't pressurize the system. Is the pump pumping at that point just to maintain whatever little pressure it has produced? I'm confused.
If it is a lowered water table, what are some of my options to get the pressure back in my zones? Larger pressure tank? More powerful pump? Any help appreciated.