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

[Valveman]

There is no difference in cycling between using that hydrant at the well head verses using one in or around the house. The only difference is that any tees after the pressure tank do not cause the water to reverse direction when the pump starts like the one at the well head does. It is not good for the pump to cycle on/off no matter where the hydrants are located. Short uses of water don't make much difference. But long uses like sprinklers and long showers can cause the pump to cycle on and off every minute or so, and there are 1440 minutes in a day. A pump just running for 30 seconds or a minute to fill the tank is not good. That is called a rapid or short cycle. Pumps need to run for a MINIUMUM of 60 seconds, two minutes is better, and running continuously while water is on is best of all, even and especially when water is being use 24/7/365 or for long periods of time.

The CSV will keep the pump from cycling itself to death no matter which or where the hydrants are located. It will also deliver strong constant 50 PSI to the showers, which will seem much stronger than when the pump is cycling on and off between 40 and 60.

And why don't all well installers use CSV's? Because CSV's "extend the life of the pump" and they like to sell pumps. Lol! Asking a pump man about a CSV is like asking an owner of a gas station if he would recommend an electric car.

 

[JimRB]

If your tank has the proper air charge you should not have hammering. We have lived on this well for 25 years on the same pump. 6-10 horses getting watered. Never have we had any hammering. Toilets and faucets are all low flow. Spigots are just spigots used to water the horses, wash the cars, fill spray tanks. Never any hammering. Hammering is an issue of you do not have a pressure tank with an air charge to absorb that surge. If you have city water with a check valve at the street you may need some hammer arrestors. They can just be some lengths of pipe capped off above valves that have small air charges in them. Water Hammer Arrestors

Note of course that well tanks with bladders are consumable items. The bladder will tear after a while and you need to replace that tank. Quite heavy when the bladder has failed. Fairly light when new. I know when the bladder has failed because you feel the surge of the pump turning on and if outside I hear the short cycling of the pump.

Where is the pressure switch mounted?

Note that if you have 60 PSI in your house, then the pump could have 100PSI or more depending on pump depth. Remember a a foot of water column is .433 psi. If your spigot is 100 feet below (not away) the storage tank, even with the pump turned off and no pressure reading you would have 43 PSI of pressure.

 

[CobyRupert]

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.

Could you get water hammer?
IDK, I more familiar with water hammer happening in a (just) closed systems, but where would the hammer show up? At a tank bladder, at an open valve?

 

[SPYDERLK]

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?

Water in the 600' line will reverse direction each time the pump turns off when the RV is using water. Some delivery effect will be noted at RV. Probably not too big an issue unless hammer develops with abrupt cutoffs in RV usage. A small surge tank at a convenient point that adds some springyness to the water column in that very long ~ 750' supply line would provide insurance.

 

[JM7500]

If you have the check valve between the spigot and the pressure switch, it will keep the pump from starting when the spigot is opened. My system has a check valve upstream from the pressure tank and pressure switch. I have a tee with a valve by my well head but have to "force" the pump on to use it.

 

[rbstern]

There is no difference in cycling between using that hydrant at the well head verses using one in or around the house. The only difference is that any tees after the pressure tank do not cause the water to reverse direction when the pump starts like the one at the well head does. It is not good for the pump to cycle on/off no matter where the hydrants are located. Short uses of water don't make much difference. But long uses like sprinklers and long showers can cause the pump to cycle on and off every minute or so, and there are 1440 minutes in a day. A pump just running for 30 seconds or a minute to fill the tank is not good. That is called a rapid or short cycle. Pumps need to run for a MINIUMUM of 60 seconds, two minutes is better, and running continuously while water is on is best of all, even and especially when water is being use 24/7/365 or for long periods of time.

The CSV will keep the pump from cycling itself to death no matter which or where the hydrants are located. It will also deliver strong constant 50 PSI to the showers, which will seem much stronger than when the pump is cycling on and off between 40 and 60.

And why don't all well installers use CSV's? Because CSV's "extend the life of the pump" and they like to sell pumps. Lol! Asking a pump man about a CSV is like asking an owner of a gas station if he would recommend an electric car.

Cool video. Very instructive. Thanks for posting.

I just timed my pump's "on" cycle. 1:26 to refill the pressure tank with all fixtures off. Under normal use patterns, it takes a fair amount of time to cycle through the full tank. However, I can see how the CSV would lengthen system life span, with a tradeoff of perhaps a little bit of extra energy cost.

It looks like the CSV125, inline before the T for my new fixture, would be the right choice.

 

[nch77]

It will be fine, I run a line like that already, but its almost 2000 feet long. The pressure will be uniform in the whole system.

 

[ponytug]

Cool video. Very instructive. Thanks for posting.

I just timed my pump's "on" cycle. 1:26 to refill the pressure tank with all fixtures off. Under normal use patterns, it takes a fair amount of time to cycle through the full tank. However, I can see how the CSV would lengthen system life span, with a tradeoff of perhaps a little bit of extra energy cost.

It looks like the CSV125, inline before the T for my new fixture, would be the right choice.

I doubt that you will see any issues in your setup without adding extra items to modulate pressure. You have a pressure tank, you have long pipe runs which work in your favor in this instance since an RV is a low flow source, and finally almost every RV has its own pressure tank.

All the best,

Peter

 

[SPYDERLK]

Could you get water hammer?
IDK, I more familiar with water hammer happening in a (just) closed systems, but where would the hammer show up? At a tank bladder, at an open valve?

It happens when water moving rapidly in a pipe is stopped quickly and rebounds and oscillates to a stop. Speed, pipe rigidity, and length of the water column all enter in to influence the severity.

 

[Valveman]

Water hammer happens every time a pump starts or stops and every time a valve is opened or closed. Any time water is started moving from a static condition, stopped from a moving condition, or changes direction water hammer happens. Even water just flowing around an elbow or split at a tee causes transient pressure waves that turn into water hammer. A pressure tank or water hammer arrestor cannot stop water hammer. They can only “arrest” it to some degree.

Water hammer or transient pressure waves travel through the pipe from 3,000 to 8,000 feet per second. Faster than a speeding bullet, water hammer travels from where it happens to the other end of the plumbing system far away before you can blink an eye. Closing any hydrant is like dropping a boulder in front of a moving train. In 600’ of 1 ¼” pipe there is 390 pounds of water. All 390 pounds of that water must come to a complete stop when you close the faucet or shower. Friction loss and the sponginess of your pipe are the only things that lessens water hammer. The softer the pipe, the slower the transient pressure wave travels. The slower the transient wave, the lower the damage from water hammer. Softer pipe like Poly only bounces back water hammer waves at 3,000 feet per second while steel pipe bounces the waves back at 8,000 feet per second.

Every time a pump starts it is instantly cramming more weight into that pipe that has 390 pounds of water sitting perfectly still. This is like trying to push a freight train to an instant start of 50 MPH. It would crush the first several freight cars the same way water is trying to split the pipe it is in. Starting the pump causes tremendous pressure pushing against the 390 pounds of water in the pipe blocking the way.

Stopping the pump causes the 390 pounds of water that is flying down the pipe at 5-7 feet per second to stop abruptly and reverse direction, slamming the check valve closed. As this water is coming to a stop from 5-7 fps speed it stretches and turns into a negative pressure. Much like stretching a rubber band, it snaps back. This slams the check valve closed and the resulting pressure wave can be many times more pressure than the pump can even produce.

The softer the pipe, the less damage from water hammer. But the softer the pipe, the less pressure it can take. Water hammer causes damage from the faucet you closed that caused it, all the way to the thrust bearing in the bottom of a submersible motor. Pin holes, splits in the pipe, broken fittings, and any other damage to the plumbing is caused by water hammer unless someone physically steps on the pipe and breaks it.

Slowly opening or closing valves or faucets is the only way to alleviate water hammer on the user side of a water system. Slow closing gate valves are much safer than quarter turn ball valves. Ball valves are my favorite, but the user needs to be trained to close them slowly. Slow closing solenoid or sprinkler valves are a must.

Eliminating water hammer on the pump side of a water system requires starting and stopping the pump against its max pressure. Starting a pump against a closed or almost closed valve lets the 390 pounds of water in the pipe start moving slowly. Closing or almost closing a valve against the pump before shutting the motor off lets the 390 pounds of water in the pipe stop moving slowly. It is also important that the valve opens up as fast as needed to keep negative pressures from being created in the line when someone uses water faster than it is coming from the pump.

This is probably more than most people want to know about water hammer. Lol! But just because your pipe has survived the abuse for 25 years doesn’t mean you don’t have water hammer. And just because your pump survived 25 years cycling on and off over and over doesn’t mean it wouldn’t have lasted twice as long if it had not been cycling. Pumps are designed to last 7 years on average. For every pump that has lasted 25 years there are a couple more that barely made it through the 1 year warranty period before they were cycled to death. For every person who has never experienced water hammer there are a couple more that can’t sleep from the pipes banging in the walls.

A Cycle Stop Valve stops the pump from being cycled on/off to death. A Cycle Stop Valve also starts and stops the pump at only 1 GPM, which eliminates water hammer. Water systems can be so complex that even most engineers are confused. Nearly all the complex issues can be resolved by using a simple Cycle Stop Valve. And before you ask why doesn’t every pump installer use them remember, nearly all issues in a water system are resolved by using a Cycle Stop Valve. That should answer your question.