Pipes Hammer when pump cuts out

[jodan]

If i am following correctly the CSV will in a sense have the pump running longer. Will that cause the pump to have an shorter than normal life expectency? Since my problem is when the pump shuts down would a CSV work? To me it fixes hammer at the start of the cycle. Unless 1GPM is sufficient to run a house hold, when it senses more water need and ramps up to 10 - 20 GPM it will hammer again at shut down, unless it ramps down before shut down. That is the way i am following at the moment. Where does this CSV go in the line? Do i need to pull the pump to install? Where are they sold? i have not come across them previously, but have not specifically looked either. Could my idea of an expansion pipe work. What i am thinking at the moment is to T into the vertical run where the line enters the house. Add a 4" piece of pipe to another T. Run a 2' piece of pipe parallel to the inlet pipe either the ame size pipe or slightly larger with a cap on it. Out the bottom i run a short piece of pipe with a screw cap. That way if the expansion pipe would happen to fill up over time i could drain it and reintroduce air to the expansion pipe. What i don't know is will it work on a vertical pipe or would it need to be on a horizontal run. Last question for the moment, can a check valve actually wear out. To my thinking the spring does not do much, back flow closes the valve. Guess some wear could occur but not enough to ruin it in a short period of time. Merry Christmas to all, gotta go.

[speedbump]

I just read through this again. Valveman says the water is moving through the pipe at 10 to 20 gpm. This is correct depending on size of submersible pump. Sam says the check valve at the top can cause water to be sucked into the suction line. True, but this would only happen with a jet pump. Jodan's pump is at 265', so we know it's a submersible pump.

So to fix this man's problem as per Ranchers request, I recommend pulling the pump and replacing the check valve. I have seen a lot of check vavles over the years go bad. Not because of the poppit so much, but because of the SS spring that slowly closes off the poppit when the volume drops as pressure rises (this spring is used to prevent hammer). I think this spring is broken and the poppit is staying close to wide open. When the pump stops, bang it closes hard, when the pump starts, bang all the way to the nut that prevents it from getting pumped into the tank. Since Jodan didn't answer my question of when he heard this noise, I will assume it is both when the pump starts and stops. This would indicate the bad spring theory.

bob...

[sammyhydro11]

I suggested that the check valve was clsoing slowly as well. And i disagree with the jet pump and check valve. Its the same principal as a chemical feed unit on some pressure washers. The high flow passing by the reservoir creates a vacume on the container drawing in the chemical.

SAM

[speedbump]

On a pressure washer Sam, they would have an ejector that will draw the bleach. That's why the nozzle is much larger than the high pressure nozzles. Ejectors will only operate between a narrow pressure range. In the case of the hole in the submersible feed line to the house, the entrie pipe will be under pressure and water will be flowing outward all the time the pump is running. There is no ejector to create a vacuum, so the only time that hole will take in water is when the submersible is turned off. Are we both on the same page, or am I misinterpreting what your saying?

bob...

[sammyhydro11]

Bob,
i'm not going to argue with you about injectors and how they work. I will say that i have seen fittings break in positions that cause water that has pooled around fittings to be sucked into water lines. If you take a peice of pipe and drill a hole into it on an angle and then send a good amount of water through it, at a good amount of speed,you will create a vacume. I have seen it happen too many times. This can happen w/water lines and broken fittings. So are we on the same page? Maybe,maybe not. Hopefuly we can get there.

SAM

[speedbump]

I never wanted to argue Sam, I just haven't seen what your describing happen before. I can see the pool that you mention being sucked back into the pipe after a sub shut off. It would only take a small leak below that spot to cause that vacuum. This is the reason a lot of say not to install a check valve at the tank or anywhere in the feed line. Without one the feed line stays pressurized all the time.

I think we are on the same page, it's just that we are describing it differently. In reality, the same thing happens, it just has a different movie title.

bob...

[Ddanrr]

So it sounds like a CSV is going to partially close, to slow down the flow rate against my pump trying to run at full speed? It doesn't sound like it would be very good for the pump. I also considered a whole house filter between the pump and the tank, to slow the water down a bit and prevent the hammer, but then the pump wants to pump at 10 gpm, and the filter 5 gpm, the pump would be fighting it. Makes me wonder if there would be an electrical way to ramp the pump down slowly, so it doesn't bang the pipes shutting off.

There have been a lot of posts here, but I'm still trying to understand why the water will hammer when the pump shuts off in a normal, small system. Because the check valve at the pump is worn and closing too slow? Would another check valve installed in the house where the pipe comes in the wall help? Or a water hammer arrestor? In other threads I understood that a bladder tank was supposed to act as a water hammer arrestor, but now it sounds like it helps cause the problem? One thing I noticed in common with the original poster is that my tank is not close to where the pipe comes in from the wall, but is across the basement on the other side. I wonder if this is a factor at all.

[speedbump]

I think what you are saying is the inline filter is a poor mans CSV. I don't think so. If you put that inline filter between the pump and tank, watch for some major problems down the line.

Is your pressure switch at this tank that is across the room or is it somewhere else?

bob...

[sammyhydro11]

If you want to stop that hammer put in that check valve at the tank. How difficult is that?? People can go back and forth on this all they want but your check valve at your pump is closing too slow. Pull it out,replace it,put a check valve at your tank,or do the csv along with the check valve at the pump.

SAM

[sammyhydro11]

Speedbump is right,that filter is a bad move. I still don't understand why you haven't tryed any of these solutions. I would say the easiest and cheapest way for now would to try that cycle stop valve or slap in a check valve at the tank. But that will be my last reply on this subject because i feel like were going in circles. SPEND SOME MONEY AND GET IT DONE

SAM

[vaplumber]

There is no check valve in the house. i started to put one in and then realized that the hydrant out side by the well head would only run until the water in the pipe was gone. Because if it does not drop the pressure tank the pump will not get tripped on. Does that make sense? i am debating weather or not to make an expansion tank in the pipe.

Dont ever put a check valve at the tank. Weve worked on many set up this way over the years. When the valve at the submersible pump starts to get weak and close slower, the valve you put at the tank will cause water hammer. Also if the check valve on the pump is weak, it can cause hammer even if you dont have any other check valves in the system. The inspectors here will fail a system if you have a check installed any where out side of the well casing. There reason being as stated earlier. If there is a leak in a pipe between the well and the tank and you put a check valve at the tank to cover a bad pump check, when the water in the drop pipe and the buried pipe to the tank falls back to the well, you build a vacuum in the line behind that new check valve, and that can cause contamination.

[jodan]

As in my reply on the 22nd the hammer occurs only when the pump turns off. As for Ranchers questions for the pressure build up. I turned the pump off, then drained the tank by opening the cold water in a tub. That did put the guage to zero. At that point i turned the ball valve to the house supply off. Why, i do not have an answer. But when i did, the pressure guage slowly rose to 25#. That is all the higher it ever went. So at that point i opened the house back up and you could hear the air enter the pipes, and the guage did go back to zero. I then turned the house back off and the pressure on the guage rose to about 25# again. At that point i cut the 1 1/4 pvc supply line where i intended on putting the check valve. Which is above the tank in a horizontal line. By all rights the water should have been gone. There was still about a gallon in that line. It did stop running, which tells me the line probably was pitched just enough away from the tank to hold the water. Yes pressure on the guage went to zero. As we all know from there i did not put the valve in, glued my pipe back in, turned on the pump, opened most all of the faucets to purge the air that was introduced. I havn't messed with anything since. Night time and holiday water repairs in the country is something i try not to do unless absolutly needed.

After todays posting it would appear that i need to pull the pump and change the check valve. I have access to cranes. Could i pull the well on my own with out alot of issues. The reason i ask is, out of six, only one well man has returned my call and his diagnosis was a bad pressure tank.

[vaplumber]

drained the tank by opening the cold water in a tub. That did put the guage to zero. At that point i turned the ball valve to the house supply off. Why, i do not have an answer. But when i did, the pressure guage slowly rose to 25#. That is all the higher it ever went. So at that point i opened the house back up and you could hear the air enter the pipes, and the guage did go back to zero. I then turned the house back off and the pressure on the guage rose to about 25# again.

This diagnosis tells me that the bladder in your tank is shot. The pressure is rising because the air that is suppose to be above the bladder is entering the water side of the tank via a small leak. This will also cause hammer as it causes the tank to become unstable and loose air. Replace the pressure tank and leave the pump alone. Also do not allow the well man to install a check valve at the tank. Trust me at this. Ive been at this since 1954, and a second check valve will only lead to trouble. Good luck.

[Rancher]

Sounds like the well man was correct in his diagnosis. I agree with Vaplumber, a small pin hole in the bladder would cause the pressure to rise, it would also account for that gallon of water you found after draining.

Rancher

[jodan]

I will get a tank, its cheaper than pulling the well. The only thing that puzzles me is that when i and the well man checked the bladder pressure it read 40#. Correct me if i am wrong but wouldn't the pressure in the bladder go down and also introduce air into the pipes in the house?