Two homes on one well

[gdcircuit]

I currently have two homes off one well pump. One is a full size home and one is a cottage. The connection diagram is attached. The only thing I left out are shutoff valves. The system appears to work fine except the tank in Home 2 is being replaced because it failed. However I want to be sure the system is designed correctly. Specifically:
1) Why would the pressure switch be set so broad in Home 1? 30-70. Is it just to reduce pump cycles, or is it in anyway related to how the jet pump in home 2 works? My concern is this high psi is what led to failure of the tank.
2) Is there a reason that no relief valve was installed in home 2?
3) Are the two pressure switch settings dependent on one another?

 

[Valveman]

I don't know how it has been working with two pressure switches. It would be hard to keep from having a cross connection when using power from two different places, plus it is not safe. Only one pressure tank is needed, even for multiple homes. The only check valve needed is the one down on the submersible pump. And yes, when I see a 30/70 pressure switch setting I know someone has been trying to reduce the cycling. Cycling by itself will destroy a pressure tank. Cycling from 30 to 80 overstretches the diaphragm and will also destroy a tank diaphragm. Cycling is hard on everything, most especially the pump.

Add a Cycle Stop Valve to eliminate the cycling and then only one small tank is needed, even for multiple houses. With the switch set to 50/70 and the CSV holding a strong constant 60 PSI you will no longer even need soap in the shower. Lol.

 

[Sponsor]

 

[Bannerman]

As Valveman stated, one submersible pump and pressure tank & switch is usually sufficient to supply multiple homes.

Perhaps the supply line diameter installed to the 2nd house is too small, thereby resulting in high flow restriction shown as excessive pressure drop during water use. This maybe the reason that a jet pump was added to boost the pressure for only the 2nd house.

While your diagram does not show the electrical wiring or supply source for the jet pump, I anticipate the jet pump power is supplied from the 2nd house and there is no electrical interconnection with the submersible well pump. The jet pump will then only operate when sufficient water flow within the 2nd house results in the supply pressure to fall below 40 psi, thereby causing the jet pump to activate to increase the flow velocity within the 200' supply line to increase the flow rate to increase pressure within the 2nd house.

When there is no water use in the 2nd house, depending on any elevation difference between the 1st & 2nd house, the static pressure observed in the 2nd house, should be fairly close to the pressure in the 1st house.

With the submersible pump's pressure switch normally set to 50-70 psi, if a larger diameter supply pipe had been installed in the additional 200' to the 2nd house, that will likely have eliminated any need and expense for an additional jet pump and associated pump control components.

Edit to add: Why is the pre-charge pressure in the submersible pump's pressure tank only 13.5 psi? The pre-charge pressure should normally be calibrated to 2 - 5 psi below the pressure switch cut-in pressure. With only a 13.5 psi pre-charge, this in addition to the excessive pressure switch setting (should normally be 20 psi differential), is further adding to the excessive stretching of the tank's internal flexible diaphragm, further contributing to the premature failure of the pressure tank.

 

[Sylvan]

I don't know how it has been working with two pressure switches. It would be hard to keep from having a cross connection when using power from two different places, plus it is not safe. Only one pressure tank is needed, even for multiple homes. The only check valve needed is the one down on the submersible pump. And yes, when I see a 30/70 pressure switch setting I know someone has been trying to reduce the cycling. Cycling by itself will destroy a pressure tank. Cycling from 30 to 80 overstretches the diaphragm and will also destroy a tank diaphragm. Cycling is hard on everything, most especially the pump.

Add a Cycle Stop Valve to eliminate the cycling and then only one small tank is needed, even for multiple houses. With the switch set to 50/70 and the CSV holding a strong constant 60 PSI you will no longer even need soap in the shower. Lol.

View attachment 106533

+

I don't know how it has been working with two pressure switches. It would be hard to keep from having a cross connection when using power from two different places, plus it is not safe. Only one pressure tank is needed, even for multiple homes. The only check valve needed is the one down on the submersible pump. And yes, when I see a 30/70 pressure switch setting I know someone has been trying to reduce the cycling. Cycling by itself will destroy a pressure tank. Cycling from 30 to 80 overstretches the diaphragm and will also destroy a tank diaphragm. Cycling is hard on everything, most especially the pump.

Add a Cycle Stop Valve to eliminate the cycling and then only one small tank is needed, even for multiple houses. With the switch set to 50/70 and the CSV holding a strong constant 60 PSI you will no longer even need soap in the shower. Lol.

View attachment 106533

 

[Sylvan]

Very informative, great answer