For a related post on setting well pump pressure switches, check here. I briefly mentioned this is my post about Well Pump installation a few weeks ago. One of the things we are getting ready to replace is our well pressure tank. The old system was not in bad shape, but since we have a new well, a new pre-pressurized Amtrol tank was in order. These tanks have a rubber bladder which holds the air and you do not have to periodically recharge the tank.
With older non-bladder tanks, you must add air every so often to replace the air that escapes, otherwise your pump will run too often risking a motor burnout. This is called short cycling and it happens because there is no air cushion for the water to compress against so the tank has become water logged. The well pressure tank system works under the principle of gases can be compressed while liquids cannot. As water fills the tank, the air bubble at the top of the tank compresses, this pressure is what forces the water into the house’s plumbing system. For more information on water logged pressure tanks, read this post.
This is a typical installation, the well pump will be connected to the pipe in the right hand side of the picture. That pipe has a shut off valve and a union. The union is there so the pipe can be “broken” open if the tank ever needs to be replaced without actually cutting the pipe. I like unions, they make life easier in the future. That pipe is connect to the brass T fitting which is connected to the tank. The brass T fitting is a specially designed tank adapter. You can make such a fitting yourself, but why bother when you buy one at a reasonable cost. The T fitting contains the pressure switch, pressure gauge, boiler drain and pressure relief valve.
On the other side of the T fitting is the pipe that feeds water to the house. On that pipe I soldered two stubs so that a water filter or water softener can be added later on. Again, I am all about making life easier in the future, when I think of it.
The directions for the pressure tank state that the pre-charge pressure must be adjusted according to the pressure switch. My switch gives a cut in (turn pump on) of 30 PSI (pounds per square inch) and a cutout (turn pump off) of 50 PSI. Therefore the precharge must be not more than 28 PSI, I may reduce it to 26 PSI to compensate for any error in the pressure switch. If the pressure switch setting were lower than the pressure tank pressure, then the tank would run out of water before the pump would turn on.
This is a list of parts for the pressure tank installation:
- Amtrol 40 gallon captive air tank
- Square D pumptrol pressure switch
- Campbell pressure gauge
- Lee brass pressure tank T adaptor
- 4 each 1 inch ball valves
- 4 each 1 inch unions
- boiler drain
- pressure relief valve
Once it stops raining around here and the ground dries out enough to dig a four foot deep trench we will finish this project by actually installing the well pump.