Well pressure tank: Does well-side supply line pressure match tank pressure?

[rbstern]

My well setup: Well head is about 600 feet from pressure tank, which is housed in basement of home.

I need a spigot about 125' in the other direction. The trenching to bring a water line from the house supply side of the pressure tank would be a big job. The distance, out through the the foundation, plus lots of obstacles, including buried fiber, electrical, and the well supply itself. In other words, if I don't have to dig it, I don't want to.

I always assumed I couldn't tee into the supply line between the well and the tank, thinking that the pump would have to be running to provide pressure. But reality then dawned on my thick skull: The supply line before the tank has the same pressure as the tank, since there are no valves or checks between the tank and the line coming from the pump (as far as I know). Do I have that right?

This diagram shows what I have in mind. The new line would be in red. The well supply line is green.

Input appreciated.

 

[stumblinhorse]

My well setup: Well head is about 600 feet from pressure tank, which is housed in basement of home.

I need a spigot about 125' in the other direction. The trenching to bring a water line from the house supply side of the pressure tank would be a big job. The distance, out through the the foundation, plus lots of obstacles, including buried fiber, electrical, and the well supply itself. In other words, if I don't have to dig it, I don't want to.

I always assumed I couldn't tee into the supply line between the well and the tank, thinking that the pump would have to be running to provide pressure. But reality then dawned on my thick skull: The supply line before the tank has the same pressure as the tank, since there are no valves or checks between the tank and the line coming from the pump (as far as I know). Do I have that right?

This diagram shows what I have in mind. The new line would be in red. The well supply line is green.

Input appreciated.

View attachment 777603

Yes, my place has a similar set up. But don’t make the same mistake that happened here. At your “can I tee here?” install a shut off valve…. Have a tee handle so you can shut off that spigot if there is a problem.

 

[stumblinhorse]

My well setup: Well head is about 600 feet from pressure tank, which is housed in basement of home.

I need a spigot about 125' in the other direction. The trenching to bring a water line from the house supply side of the pressure tank would be a big job. The distance, out through the the foundation, plus lots of obstacles, including buried fiber, electrical, and the well supply itself. In other words, if I don't have to dig it, I don't want to.

I always assumed I couldn't tee into the supply line between the well and the tank, thinking that the pump would have to be running to provide pressure. But reality then dawned on my thick skull: The supply line before the tank has the same pressure as the tank, since there are no valves or checks between the tank and the line coming from the pump (as far as I know). Do I have that right?

This diagram shows what I have in mind. The new line would be in red. The well supply line is green.

Input appreciated.

View attachment 777603

Oh and 1 more thing for your picture. The entire line is 40 to 60 psi not just after the well tank…

 

[bcp]

It will be easier to see what is happening with these changes to the tank diagram.




Bruce

 

[ponytug]

My well setup: Well head is about 600 feet from pressure tank, which is housed in basement of home.

I need a spigot about 125' in the other direction. The trenching to bring a water line from the house supply side of the pressure tank would be a big job. The distance, out through the the foundation, plus lots of obstacles, including buried fiber, electrical, and the well supply itself. In other words, if I don't have to dig it, I don't want to.

I always assumed I couldn't tee into the supply line between the well and the tank, thinking that the pump would have to be running to provide pressure. But reality then dawned on my thick skull: The supply line before the tank has the same pressure as the tank, since there are no valves or checks between the tank and the line coming from the pump (as far as I know). Do I have that right?

This diagram shows what I have in mind. The new line would be in red. The well supply line is green.

Input appreciated.

View attachment 777603

That's close to what I have, but just to be clear; you would need to have no check valves after the pipe leaves the well head, and before the well tank.

Teeing into an existing line takes some work, and the amount depends on whether the pipe is galvanized, PVC, or tubing, but it can be done, and would probably be way less effort than an extra 725' trench. If it were me, I would put gate valves on both the house and the spigot lines with unions at each valve for easy replacement. I find myself isolating lines all the time to trouble shoot / fix things. I would also think about putting all of the valves and tee in a vault or valve box for easy future repairs.

All the best,

Peter

 

[SPYDERLK]

It will be fine. A cutoff valve in the Tee line is a good idea posed earlier. Im sure you will be entertained by the pause in the aux flow you will experience every time the pump turns off.

 

[LouNY]

It can work as long as you don't have a check valve close to your pressure tank as is quite common. Otherwise the check could be at the top of the pump or at your pitless adapter.
My check is at the top of the pump line were it goes to the pitless adapter, my tee for the outside hydrant is just a short distance from the well
very much as you are wanting to do.
I issue that I have is that I run a low pressure cutoff pressure switch in case a line breaks low pressure will shut down the pump. When the hydrant is opened quickly the pressure drops quickly in the line and the switch will shut the system down.
If the hydrant is opened slowly the sudden pressure drop doesn't happen and everything works good.

 

[Valveman]

As was said, as long as there are no check valves above ground it will work. The only check valve you want or need is the one down the well on the pump itself.

But think about this. When you open that faucet the water first comes back from the tank. When the pressure drops to 40 and the pump comes on, now the water at the faucet is coming from the well pump. This is why the pressure will seem much lower when the pump shuts off as was mentioned above. Not only does it make the pressure pulse, but can cause water hammer as the flow changes direction from forward to back over and over. As when using any faucets on a well pump, make sure the faucet is large enough or use multiple faucets to let out enough water to keep the pump from cycling on and off. If you have a 10 GPM pump, make sure to always use 10 GPM at the faucets. Using anything from 1 GPM to 9 GPM will cause a 10 GPM pump to cycle on and off continuously. Cycling on and off is bad for the pump, tank, check valve, pressure switch, and everything in a pump system. When using that faucet at less than 10 GPM the pump will cycle on and off as well as cause water hammer as the water in the pipe changes direction every minute of so.

You can solve all these problems by adding a Cycle Stop Valve. The CSV needs to be installed prior to any tees in the line. We make one that fits in the well for just these type systems. But you could also add a CSV1A in the line prior to the tee to the first faucet if you had rather. Even when installed at the well head like that, the CSV will deliver strong constant pressure to the first faucet as well as the last shower on the line.

The main purpose of a CSV is to make pump systems last longer, but is solves many other problems as well.

 

[SPYDERLK]

I think water hammer may happen in abrupt valving situation at the aux valve, but that the problem is not probable in general. Should be able to totally defuse the chance with a very small surge tank/bottle at the Tee connection point.

 

[rbstern]

As was said, as long as there are no check valves above ground it will work. The only check valve you want or need is the one down the well on the pump itself.

But think about this. When you open that faucet the water first comes back from the tank. When the pressure drops to 40 and the pump comes on, now the water at the faucet is coming from the well pump. This is why the pressure will seem much lower when the pump shuts off as was mentioned above. Not only does it make the pressure pulse, but can cause water hammer as the flow changes direction from forward to back over and over. As when using any faucets on a well pump, make sure the faucet is large enough or use multiple faucets to let out enough water to keep the pump from cycling on and off. If you have a 10 GPM pump, make sure to always use 10 GPM at the faucets. Using anything from 1 GPM to 9 GPM will cause a 10 GPM pump to cycle on and off continuously. Cycling on and off is bad for the pump, tank, check valve, pressure switch, and everything in a pump system. When using that faucet at less than 10 GPM the pump will cycle on and off as well as cause water hammer as the water in the pipe changes direction every minute of so.

You can solve all these problems by adding a Cycle Stop Valve. The CSV needs to be installed prior to any tees in the line. We make one that fits in the well for just these type systems. But you could also add a CSV1A in the line prior to the tee to the first faucet if you had rather. Even when installed at the well head like that, the CSV will deliver strong constant pressure to the first faucet as well as the last shower on the line.

The main purpose of a CSV is to make pump systems last longer, but is solves many other problems as well.

Very much appreciate the detailed comment.

I'm trying to understand the implications of this for my setup. We have an 85 gallon pressure tank, which yields about 25 gallons at 40 to 60psi. For normal, household use, cycling is very infrequent. When it cycles on at 40 psi, the pump runs for perhaps 30 seconds to a minute (I should probably time this) to boost the pressure to 60psi.

The spigot in question is going to serve as a hookup for an RV.

So, let's say someone is showering in the RV, and the well tank pressure drops to 40psi, causing the pump to turn on. The pump output is MUCH higher than the RV's shower head. My expectation would be, there would be a surge in pressure at the showerhead, but that the pump would simultaneously be refilling the well tank, albeit, a little slower than if the fixture wasn't open.

In reality, this is no different than any other fixture on the same system. If I was using the basement sink, which sits right next to the pressure tank, the same thing would happen.

I guess I'm not understanding why there would be increased cycling or different behavior from that first fixture off the tee, vs. one that was on the other side of the tank, when the tank is receiving water, along with a fixture after the tank. Assuming the pump supplied pressure is approximately equal all along the supply line, the fixtures should all behave the same, should they not?