Subject: [Shop-talk] Well water hammer?

From: Jim Franklin <[email-masked]>
Date: Tue, 26 Aug 2014 12:12:44 -0400

I've been hearing water hammer that I thought was the washing machine turning
off and rattling the pipes, but when I'd go into the basement and watch, it
never hammered. This morning I woke up to the well cycling. Investigation
showed the pressure was leaking back down the supply pipe. I replaced the
Flowmatic check valve with a $16 American Granby (the Nibco was $65).

Now when the pump kicks on there is a significant hammer, about 1/2 second
after the switch triggers the pump. The check valve spring was pretty light so
it isn't that.

Any ideas on what's going on here? I'm wondering if something is wrong that
killed the check valve. It looked original, 30 years old, spring had come
undone and gotten stuck in the valve.

thanks,
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From: "Peter J. Thomas" <[email-masked]>
Date: Tue, 26 Aug 2014 13:35:15 -0400

-------- Original Message --------
Subject: 	Re: [Shop-talk] Well water hammer?
Date: 	Tue, 26 Aug 2014 13:03:23 -0400
From: 	Peter J. Thomas <[email-masked]>
To: 	Jim Franklin <[email-masked]>

On 8/26/2014 12:44 PM, Jim Franklin wrote:
> On Aug 26, 2014, at 12:34 PM, Peter J. Thomas wrote:
>> Check the pressure tank.  You can use a regular tire gauge.
> 42 psi. This is with the tank full of water, not empty.
>
> jim
>
You need to check the Schrader value with the tank empty of water and no
pressure on the water side (drain open).  With the tank empty of water
there still should be some pressure on the air side of the bladder,
can't remember the amount.  Reading with water in a failed tank a small
pocket of pressurized air.  This will cause the pump to cycle often and
hammer.
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From: Randall <[email-masked]>
Date: Tue, 26 Aug 2014 18:01:40 +0000

> can't remember the amount.  

Another, less scientific approach, is to just close off the inlet and open an outlet where you can see it.  Wait until the flow stops, then add a little air.  If you get some more flow out, add a little more air.  Repeat until the extra air doesn't dispel any water.  That will still be less than it should have, but enough to prevent water hammer and rapid cycling.

Randall

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From: Jim Franklin <[email-masked]>
Date: Tue, 26 Aug 2014 14:45:14 -0400

On Aug 26, 2014, at 2:01 PM, Randall wrote:

> Another, less scientific approach, is to just close off the inlet and open
an outlet where you can see it.  Wait until the flow stops, then add a little
air.  If you get some more flow out, add a little more air.  Repeat until the
extra air doesn't dispel any water.  That will still be less than it should
have, but enough to prevent water hammer and rapid cycling.

What's causing the water hammer? I've never heard of it when something turns
_on_.

jim

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From: Jim Franklin <[email-masked]>
Date: Tue, 26 Aug 2014 21:47:27 -0400

Resending to the actual list...

On Aug 26, 2014, at 2:45 PM, Jim Franklin wrote:
> Ok, the good news is, there was only 18 psi in there. The bad news is, it
lost 22 psi over the past year. So while I regained the water pressure I
hadn't really noticed was gone, it looks like this tank may be exiting it's
mortal coil. It's a 2003 Welltrol 203, tall & skinny and a model reputed to
have issues.
>
> The tank also expelled a bunch of air upon emptying, probably because when I
removed the inlet pipe, the broken, or lack of, a check valve at the pump
allowed all the water to drain back. It doesn't seem like this was a factor in
the water hammer though, because the hammer still there. Switch clicks, wait a
2 count, and bang and the gauge goes bouncy.
>
> Unless you all have any more ideas, I'll let it run a few days and let any
air still in the water side make its way out, see if anything changes. I
really hope the pump isn't going...

[email-masked]

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From: "Peter J. Thomas" <[email-masked]>
Date: Wed, 27 Aug 2014 09:10:23 -0400

> really hope the pump isn't going...

18 is low.  Should be 38 PSI.   This is the reason for the hammer. Pumps 
run at much higher pressure ( around 100 psi IIRC).  Its quicking 
compressing the air.  So you have less than half the air in there you 
should have.  So when the pump brings it up to 42 PSI it quickly 
compresses the smaller volume of air causing hammering.  You might try 
tightening the Schrader value or replacing since they are cheap.  Turn 
off the pump, empty the water, replace the value, precharge to 38 PSI 
and wait with the drain open to see if it holds.  If it doesn't hold 
with a new Schrader value, the diaphragm/bladder is damaged and the tank 
toast.  If it holds you should be good to go.

My Welltrol slowly lost pressure out the Schrader but in my case the 
pressure relief dumped water on the basement floor.   The cycling wore 
out the spring and I had to replace the pressure value.

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