One well, two houses/tanks, only one pressure regulator

[Ron Lutterbie]

I just bought a property that has two houses (joined by a common garage) that use the same well. The first house supplies elec to the pump and the #1 tank there has a pressure switch. The second house has the second tank in the basement with a water line entering from well below grade and going into tank #2, no electric or pressure switch. I cannot find a water line going from the #1 tank in the first house to the #2 tank in the second house. I'm assuming every tank must have a pressure switch, so I'm stumped. Any input is appreciated.

 

[Bannerman]

There should only be one pressure tank and one pressure switch regardless of the number of houses.

The pressure tank's purpose is to limit pump cycling. Water comes from the well, not the pressure tank.

When less water is consumed than the pump can delivers the excess flows into the pressure tank until the pressure switch shut off pressure is satisfied whereby the pump will be shut off. If water continues to be used, the water exits the tank to flow where it is needed until the pressure drops sufficiently to cause the pressure switch to reactivate the pump and so repeating the process. Water exiting a single pressure tank located in one home, will flow to the other home through the common supply line.

 

[Sponsor]

 

[Reach4]

It is possible to have two pressure tanks but only one pressure switch, however there can be some negative effects.

This could in theory set up an oscillation. One way to prevent an oscillation would be to have a check valve in the path feeding the second tank (the tank with no pressure switch).

You don't want a check valve in the path to the first pressure tank.

 

[Ron Lutterbie]

I had the guy the installed the well come out to the house. He confirmed that the second tank is really serving no purpose( installed AFTER he did the original install and not by him) as it has no pressure switch and is simply installed on the line going into the second house. He said that the water line to the second house T's off the well BEFORE the pressure switch in the first house, so I'm confused as to how the second house is getting any water pressure unless the pump comes on every time water is needed in the second house. He said there is some 'back pressure' from the first tank in the first house? Very odd configuration. Still don't understand it.

 

[Reach4]

I had the guy the installed the well come out to the house. He confirmed that the second tank is really serving no purpose( installed AFTER he did the original install and not by him) as it has no pressure switch and is simply installed on the line going into the second house. He said that the water line to the second house T's off the well BEFORE the pressure switch in the first house, so I'm confused as to how the second house is getting any water pressure unless the pump comes on every time water is needed in the second house.

If the second house uses water, and the pressure drops lower than the pressure of the main pressure tank, the main tank will supply water. As the pressure drops at the main tank and pressure switch, the pump comes on and fills the tank(s). It is fairly common to tee off water before the pressure switch.

He said there is some 'back pressure' from the first tank in the first house? Very odd configuration. Still don't understand it.

Not sure what that might have been. Maybe he said back flow? So if house 2 is not using water, but house 1 is, water will flow out of tank 2 toward house 1.

Is there any symptom of a problem? If there is, consider putting a check valve in the line going to house 2.

Why could there be a need for a second tank? If we imagine the pipe to house 2 is undersized, a pressure tank could slow momentary pressure drops. As an example, but not likely, scenario, suppose house 2 had a Flushomatic toilet. That is like the commercial toilets with no tank. They draw many gpm for a few seconds. Or more realistic, suppose the washing machine draws water in spurts during some cycles.

I am not saying this was the motivation. More likely, I think, was somebody thought this would increase pressure at house 2. Not really going to happen.

Does the current resident of house 2 provide insight?

While there is potential downside, the two tank have some advantage in making it almost like a bigger tank that is the sum of the two capacities. But there are these strange effects that could happen. Maybe they don't and the 2 tanks get along fine in practice.

How is the water? Any smells? https://terrylove.com/forums/index....izing-extra-attention-to-4-inch-casing.65845/ is my sanitizing writeup.

 

[Bannerman]

A single pressure tank will maintain pressure on the entire system, including the pipe leading directly from the pump while the pump is not operating. Water use in either home will cause the pressure in the entire system to become lower until the pressure switch causes the pump to become activated.

If for instance the pump can supply 10 GPM but water use in either home is only 3 GPM to supply 1 shower, then the pump will supply 3 GPM to the shower, and the remaining 7 GPM will flow into the pressure tank. With a 40/60 psi system, pressure will rise as the pressure tank is filling so once 60 psi is acheived, the pump will be shut down. Further water flow to the shower will then be supplied from the pressure tank as the air pressure in the tank will push water out from the tank, back into the supply line feeding both homes. Once the pressure falls to 40 psi, the pump will be reactivated, causing the process to be repeated.

The pressure tank should be located nearby to the pressure switch. When the pressure tank is too small to provide the required minimum pump run time, sometimes instead of replacing with a larger tank, a second tank will be installed to increase capacity. Even with 2 tanks, they would normally both be located together nearby to the pressure switch.

When a 2nd tank is located a distance from the 1st tank, there can be sufficient flow restriction through the long pipe between them to cause the furthest tank to fill slower than the 1st tank which can result in the pump being shut down before the furthest tank is completely filled. The 1st tank will then continue to supply water continuing to enter the 2nd tank which depending on the flow restriction between both tanks, may result in sufficient pressure drop at the pressure switch to cause the pump to become activated again for a short period to top-up the first tank.

Because the purpose for an adequately sized pressure tank is to reduce pump cycling, locating a 2nd tank remotely from the 1st may actually cause additional cycling that likely would not have occured even while using a single undersized tank.

 

[Valveman]

A single pressure tank will maintain pressure on the entire system, including the pipe leading directly from the pump while the pump is not operating. Water use in either home will cause the pressure in the entire system to become lower until the pressure switch causes the pump to become activated.

If for instance the pump can supply 10 GPM but water use in either home is only 3 GPM to supply 1 shower, then the pump will supply 3 GPM to the shower, and the remaining 7 GPM will flow into the pressure tank. With a 40/60 psi system, pressure will rise as the pressure tank is filling so once 60 psi is acheived, the pump will be shut down. Further water flow to the shower will then be supplied from the pressure tank as the air pressure in the tank will push water out from the tank, back into the supply line feeding both homes. Once the pressure falls to 40 psi, the pump will be reactivated, causing the process to be repeated.

The pressure tank should be located nearby to the pressure switch. When the pressure tank is too small to provide the required minimum pump run time, sometimes instead of replacing with a larger tank, a second tank will be installed to increase capacity. Even with 2 tanks, they would normally both be located together nearby to the pressure switch.

When a 2nd tank is located a distance from the 1st tank, there can be sufficient flow restriction through the long pipe between them to cause the furthest tank to fill slower than the 1st tank which can result in the pump being shut down before the furthest tank is completely filled. The 1st tank will then continue to supply water continuing to enter the 2nd tank which depending on the flow restriction between both tanks, may result in sufficient pressure drop at the pressure switch to cause the pump to become activated again for a short period to top-up the first tank.

Because the purpose for an adequately sized pressure tank is to reduce pump cycling, locating a 2nd tank remotely from the 1st may actually cause additional cycling that likely would not have occured even while using a single undersized tank.

And of course the pump would not be cycling on and off and multiple tanks in different locations will fill at the same rate when using a Cycle Stop Valve before the first tee. But with a Cycle Stop Valve you could also supply both houses with a single 10 gallon size tank if you wanted.

 

[Ron Lutterbie]

I really appreciate all the input, I'm learning a lot here. My original post was just to understand my seemingly odd set up. I have very good water pressure in both houses, over 35 GPM, and when I was doing the inspection prior to buying, I let it run for an hour and it didn't reduce. Water quality is also very good. My thought now is that the original owner of the home added the second tank thinking it would add capacity/pressure to the second house. I'm not convinced it does, but it all works so I'm not changing a thing. I did just put in a whole house generator so I will be adding the the well pump to that new breaker box, as we have alot of power outages. Thanks for all the input folks!

 

[Bannerman]

The Cycle Stop Valve that Valveman mentioned, will allow your exsisting system to function more efficiently as it will eliminate cycling by the pump, and will provide constant pressure to both homes once the pump is operating.

Because the CSV will only fill the pressure tanks after there is no further water usage, the 2 tanks located some distance apart will not be an issue as they will fill at only 1 GPM so the long pipe between will not cause any restriction or flow delay.

To install a CSV, it will need to be located prior to where the feed line branches off to both homes. When the branch is prior to the pressure tank & switch as in your application, placing the CSV within the well is usually the most appropriate location.

 

[Ron Lutterbie]

Very interesting animation and very informative. Admitting I don't know a ton about well systems up front, I don't quite agree with the theory that during the morning and evening water is almost continually being called for by the different appliances and shower etc. Since this theory is the main reason cycling is reduced, in my house with just three people, it would still cycle a lot. I get that it will eliminate cycles during the limited instances where concurrent water usage is called for and thus run a bit less, but unless you have a huge family using the well system, the benefits seem overstated.

 

[Valveman]

Since this theory is the main reason cycling is reduced, in my house with just three people, it would still cycle a lot. I get that it will eliminate cycles during the limited instances where concurrent water usage is called for and thus run a bit less, but unless you have a huge family using the well system, the benefits seem overstated.

Although you can use the CSV with ANY SIZE TANK you want, it will not cycle "a lot" even with the small tank. The number of cycles per day are the same with a big tank cycling for any use of water, or the CSV and small tank cycling occasionally for only the small uses of water. I have never had anyone that wanted to return a Cycle Stop Valve. As a matter of fact the customers are the ones "overstating" how good the CSV works, not me. I am just repeating what the customers say as you can see here.

https://cyclestopvalves.com/pages/reviews