Water Hammer Issue

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Reach4

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f I understand the check valve issue correctly, and I'm not pretending that I do, multiple check valves interfere with the normal, somewhat gentle pressure ramp up/down as the pump starts and stops. The water hammer is actually caused by the resulting, momentarily higher pressure wave.
As I picture it, I think that there can be a minute leak that water can barely leak from. That leak could be to outside of the pipe, or it could be through a lower check valve, and a bit of water exits the pump. If there is no check valve in the way, the pressure tank will maintain pressure, so no vacuum forms.

If there is a check valve at the pressure tank, then that tiny leak will cause a vacuum to form. Then as the pump starts, the water column rises, gaining momentum, and slams into the check valve.
 

Valveman

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Water hammer on pump[ start is caused by having more than one check valve. A check valve right on top of the pump is the only one you want. Having another check valve 20' up. at the pitless, or at the tank tee can cause water hammer on pump start. Having water hammer on pump start wears out the check valves and makes them stick. Then you also get water hammer on pump stop, as the check valve is stuck and will not close until the water reverses direction, which causes water hammer. You are going to need to pull the pump, remove all check valves, and replace the check valve on the pump with a new spring loaded poppet style check valve.

Sometimes just installing a Cycle Stop Valve will stop the water hammer on pump stop, as the CSV reduces flow to 1 GPM before the pump shuts off. However, if the check valve is sticking bad, even installing a CSV won't help, and also won't do anything for water hammer on pump start. After you get the check valve situation corrected, adding a CSV will keep you from wearing out the new check valve, and will help with lots of other things as well.
 

Tenaya

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I really appreciate everyone's input - this forum is a wealth of knowledge.

When I started this post, I was hoping for a simpler (and cheaper) solution, but it doesn't seem to have gone that way. I'm going to have to think long and hard before having the driller pull the pump. I have no idea how to get my mind around the notion that everything between the pump and the pressure tank is wrong and should be replaced. The builder, the driller and the plumber are all well respected large contractors with decades of experience in their fields (40+ and 60+ years respectively). I'm struggling to understand how they could make such flaws in the basic system design.

I will most certainly address the water hammer with the driller and/or plumber, but that's not going to happen for a while. I don't want to turn this discussion to turn toward the dark side, but COVID-19 has infected everything (pun intended). We are in our 70's with underlying health challenges. We currently leave the house very, very rarely and never allow anyone to visit us, including family and service technicians. That means the water hammer will continue for a while - at least until we receive our second round of vaccine shots.

SO, my new questions are:
  • Is my water system at immediate risk in the form of a failure in the 1" PEX line from the pump to the well tee?
  • Is the internal PEX also at risk of failure (the water hammer doesn't seem to propagate past the well tee)?
In other words, how much hammering can crimped-ring PEX stand? The water system in my house has been this way since the house was completed in mid-2016, but has only seen daily use by a family of 3 since mid-2018 (we didn't move in right away).

Tenaya
 

Reach4

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  • Is my water system at immediate risk in the form of a failure in the 1" PEX line from the pump to the well tee?
  • Is the internal PEX also at risk of failure (the water hammer doesn't seem to propagate past the well tee)?
I think the answer to both is no, unless your well pumps hot water or the pressure will hit over 160. Not immediate, and not later. I am not a pro.
https://www.pexuniverse.com/pex-tubing-technical-specs
 

Valveman

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Time and pressure can wear out anything. Just like the guy in Shawshank Redemption used a little rock hammer to tunnel through thick concrete walls, water hammer pecks at everything. Water hammer can break anything/everything from your faucet to the thrust bearing in the bottom of the submersible motor. Every time you hear that water hammer "thump" a pressure wave several times the magnitude of normal house pressure has just bounced from one end of your system to the other. The longer you wait, the more chance of a failure.
 

Sarg

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Being a master of procrastination & sloth .... I'm also burdened by being a worry-wart over potential "issues" ..... like a water system that is destined to fail.
Covid is somewhere near the bottom of my list to worry about ... and I'm also near the end of the rainbow.
Different strokes for different folks. But I will say ... I would mandate the replacement of the well system from the pump to the well head.
I would not pay someone to pull and then not replace. And I would seek a "different" company.
Do it once again ... with only one check valve at the pump .... in my case the money spent was worth the elimination of worry.
Reading your original post .. your system is not old but truly appears flawed from the get go.

At the very least I would suggest following Valveman's advice:
You are going to need to pull the pump, remove all check valves, and replace the check valve on the pump with a new spring loaded poppet style check valve.
 
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Tenaya

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I'd like to thank everyone who contributed to my understanding of the problem.

My plan is to brave the consequences of doing nothing for another 45 days or so (2nd vaccine inoculation), then contact the driller AND the plumbing contractor. It will be interesting to see what solutions they propose and who takes how much responsibility.

Tenaya
 

VAWellDriller

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I don't think that your pex size in the ground is an issue here.....for me or anyone to really know if this was a problem we would need to know what pump model you have installed and the flow rate. 5 ft /sec was thrown out above as a maximum fluid velocity in piping. I agree that excessive velocity can cause problems....there are numerous standards on this regarding all different types of piping and uses. Around here, the engineers use 10 ft per second for as a max for sizing drop pipe and supply lines. I can't find it anywhere right now but I'm pretty sure it is an AWWA standard. Start with eliminating the multiple check valves. That's the simplest, easiest, and most likely solution to your problem.
 
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