Pipes Hammer when pump cuts out

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Speedbump

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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

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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

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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

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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

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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
 
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vaplumber

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jodan said:
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

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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.
 
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vaplumber

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jodan said:
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.
 
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Rancher

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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

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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?
 

jodan

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jodan

i suspected that. What about pressure drop in the bladder.
 
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Rancher

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jodan said:
i suspected that. What about pressure drop in the bladder.
Did you measure the air pressure in the bladder when you emptyed the tank, it should have been around 25# if it was leaking like we suspect. If so that was probably the source of your water hammer. It should have been 2psi less than the cut in of your pressure switch... 40psi?

Rancher
 

jodan

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jodan

I have installed the new tank.
It did not fix the hammer.
I did check the old tank before i removed it. Confirmed bad.
I did check the new tank pressure, i had to had air to get it to the 38#. I did all of that before install. I then ran the pump and filled the system. I then ran every faucet in the house and outside to purge the air. I have drained the system down a second time and and rechecked the tank bladder pressure. I did add about a 2 pounds which brought it back up to 38#. I did notice that the pressure guage does not drop all the way to zero, it stops at about 5#. But on the same note it does note build pressure either. I have opened every faucet again to purge air. I have also cycled the pump by running water. Pump starts at 40# and stops at 60#. But i still have hammer when the pump stops, same as before no change.
 

Sammyhydro11

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Wow,
i guess i would be a very angry customer if someone told me that replacing my tank would fix my water hammer propblem.......and it didn't. Come to new england fellas and every well system has a check valve right at the holding tank. I guess they should all be removed. And i wonder why they say you should have a check valve every 250'. It couldn't have anything to do with water hammer.....could it??

Jodan,
I know with putting a check valve at your tank would prevent you from using your hydrant but i was looking to prove a point. You need to pull that pump and replace that check valve like i first stated.

SAM
 
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vaplumber

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sammyhydro11 said:
Wow,
i guess i would be a very angry customer if someone told me that replacing my tank would fix my water hammer propblem.......and it didn't. Come to new england fellas and every well system has a check valve right at the holding tank. I guess they should all be removed. And i wonder why they say you should have a check valve every 250'. It couldn't have anything to do with water hammer.....could it??

Jodan,
I know with putting a check valve at your tank would prevent you from using your hydrant but i was looking to prove a point. You need to pull that pump and replace that check valve like i first stated.

SAM

Sammy, I didnt mean to insult your intelligence here. I posted that based on my own experiences and what has worked for me. A check valve every 250 feet, some thing that I have been taught here in pump seminars is that the 250 foot rule applies to well depth and water level specs, and no it doesnt relate to hammer. It's simply to reduce the workload on the valve down in the well. There are several wells here that are over 800 feet, and my own experience shows me that they will work great for many years with only the check on the pump, and to forget the 250 foot depth rule. Some thing else that time has taught me is the diagnosis of a bladder tank. A very small leak in the bladder will allow the air pressure to drop without water showing up above the bladder. If the bladder becomes unstable, ie air pressure drops during drawdown, then rises during a pump cycle, when the pump kicks, you'll get a hammer. The pressure rising with pump off and valve closed tells me that air from the bladder is entering the water side of the system. The extra gallon of water that he drained after draining the tank, which shouldnt have been there after the bladder bottomed, tells me he has a bad tank. The water entered the air side through the small leak, and when he drained the tank, the air pressure forced the water back out of the bladder. I dont know about new england, but here any check valve installed has to be inside of the well casing and below the pitless adapter, and that even includes the foot valve for jet pumps. Yea a check valve at the tank would probably resolve the hammer caused by a slow leak, but thats like using a band aid for a gunshot wound. You might stop the bleeding, but wait until time lets the infection and lead poison set in. Once again, I didnt mean it as an insult. I have learned a great deal from this forum, and hopefuly I can learn a lot more, plus I hope to pass at least one thing along to some one else as well. Maybe youre right, and Im wrong, but if thats the case, I wont take it as an isult. Just some thing that a universal friend taught to me.
 
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Speedbump

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Having lived and worked in Michigan since they introduced licensing back in the 60's them moving to Florida 25 years ago, I see two different mentalities. In Michigan just like where VAPlumber lives, a check valve above ground is illegal. The reason is the vacuum that can be put on the suction/pressure line from home to well. Here in Florida, or at least in my county of Hillsborough, we have been regulated first by the health department, then the building department and now the plumbing department. The Chief Inspector (yes about as smart as Inspector Cluso) decided to take it upon himself to add a check valve in the pipe between the well and tank. He doesn't know why, he just thinks it is a good idea. I argued with him about it to no avail.

I don't think any of us argue that a check valve won't stop the water from running back down the well, it's just that after the fact it's a big band aid masking a larger problem.

bob...
 

jodan

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jodan

It appears i have two issues. But i do know the tank was bad. Sam i know you want a check valve at the tank. But i still want my hydrant to work and it is to cold to run the second line to the hydrant, at least for me to want to do right now with frost. How difficult is the pulling of the pump? As stated before, i have cranes. Can it be accomplished that way? My quote to pull the pump was around $500. I'll battle that for a $20 valve.
 

jodan

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jodan

I found out the well information from a well drilling company off of his platte map. He quoted me the names dates and address, so it should be good info. As for teh man that put the well in, i have left another of many messages on his phone with no response yet.
 

Gary Slusser

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Franklin Electric makes pump motors, not pumps. Some (wet end) pump manufacturers also suggest a check valve every 250'. In both cases they are trying to protect their product, not solve other issues and probably don't care much if their fix causes other problems.

One check at or in the submersible pump is the best choice. That's for a number of reasons and all are good but the best is because a second check anywhere very successfully hides leaks.

I say your problem may be caused by the length of pipe from the wall to the pressure tank and its anchoring/stabilization. If it moves and the movement causes a noise, you'll call it water hammer. If it moves or doesn't and you are hearing a bang/boom type noise, then you have real water hammer and I say the cause is a leaking check valve in or on the outlet of your submersible pump. It needs to be replaced.

Pulling a 300' deep pump on PE pipe is difficult to impossible to do by hand. It is easier with a leaking check dumping the water in the pipe as you pull it though. On galvanized pipe you need a derrick truck or pump pulling machine. A crane/backhoe etc. ... how you change the grip on the drop pipe would be a problem, you need to hold the pipe and pump from falling down the well as you undo 10-20' sections of pipe. With PE you don't take it apart but you still have to hold it as you change the grip or rest.

That $500 charge to pull your pump, it's well worth it; especially when you've never seen it done or done it before. You may not believe me until after attempting it on your own to "save" $300; or doing it on your own, but you'll more than likely say never again; especially if you do something wrong.

Here's what I would do if I were there... Shut off the power to the pump. Shut off the water to the house PAST the pressure tank. Drain all water out of the pressure tank. Check the air pressure to be 39-38 psi. Turn on the power to the pump and watch the gauge and note the cut-out setting psi. Watch the gauge for the next 10 minutes looking for a loss of pressure. If the pressure holds, there is no leak from the tank to the check/pump. If you don't shut off the water to the house past the tank, you get to measure the weight of water above the tank...

I would not install any type of hammer arrestor(or anything that can block up as a filter can) between a pump and pressure tank. The arrestors eventually fill with water due to the trapped air being absorbed into the water. Anything that can block up can cause major damage. That can take only a few weeks. You need to fix the cause of the problem rather than silence the symptom. Water hammer is very destructive, so not removing the cause allows pipe and pump etc. to be damaged and cause other problems later.
 
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