Low Pressure When Irrigation System is Running
I have a well that is producing 30 gpm. This well is supplying water for the geothermal HVAC systems in my house (I am on public water for all other uses). When the HVAC systems are running, the water flow is approximately 18 gpm, and the pressure is approximately 40 psi. The relay on the storage tank is set to turn ON the pumop at 40psi, and to shut OFF at 60psi.
I had an irrigation company install an irrigation system this past week. The irrigation company used a combination of Rainbird 1812 PRS spray heads and 5012 rotors. As a side note, the designer had spec'd Toro 570 heads, but the people that installed the system used the Rainbird heads. I don't know whether this makes any difference.
On Friday, they powered up the system, and it is not working well. When the irrigation system is running, the water pressure drops to 35 psi, which is insufficient to raise the spray heads the full 12 inches (they raise perhaps 4 inches), and the water coming out is more of a pissing than a speay. The operation of the HVAC equipment does not appear to be affected; they continue to operate without any change in flow rate.
The well pump (a Grundos pump) is approximately 180 feet down the well, in the backyard. My property is on a slope. The storage tank, which is in the basement, is approximately 15 feet above the top of the well casing. The irrigation heads are approximately 10 to 18 feet above the storage tank (depending on the location of the particular irrigation head).
I have verified that when the HVAC systems are not running, the irrigation system works well. Thus, I have concluded that there is a pressure problem. The installers indicated that they will "go back to the lab" to figure out a solution, but I would like to see what people here think. I see three solutions. The first is to create an interface that shuts OFF the HVAC systems when the irrigation system is running. This solution is not optimal, because I have 11 zones, meaning the HVAC systems would have to shut down for several hours, which would raise the temperature in the house. The second solution would be to install some sort of pump to increase the pressure. However, this would likely be expensive, and I am not certain where the pump could be installed that would be away from the elements, close to an electrical supply line, and not create noise when it is operating. The third solution (that I see), would be to change the heads in the system to heads designed to operate under low pressure conditions. Are there such heads? Would the Toro heads (which the designer called for) have been better than the Rainbird heads? Would there be better heads still?
Finally, are there any other solutions that i may not have thought of yet?
Thanks
Steve