Water hammer

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Gregg G

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2nd bath is on west side of house, right next to entry point for water line from our well. Tub/shower combo, toilet and sink. Never hear any "hammer" like noises. Kitchen is in middle of house on south side - don't hear any hammer noises.
Laundry room is in middle of house on north side, across from kitchen and sharing a wall with master bath. Washer
hot and cold water lines have "mini-restors" - no hammer noises.

Master bath has toilet sharing wall with laundry room - hear hammer when toilet finishes filling. Master bath vanity
on east wall - hear hammer when sink is shut off, hot and cold.

Didn't hear it for a while, but not it has reappeared. I'll get down in the crawl space and have the wife flush and cycle vanity valves while I look for source of sound. Is it possible that it's just a "loose" pipe? I mean, one that is bouncing
around from not being tightly secured? I installed all CPVC and followed code for securing intervals. If the source
is elusive (as they have been in the past for me), would it make sense to install another set of "mini-restors" in the
supply lines under the master bath?
 

Jeff H Young

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Absolutely you have 2 plausible solutions. I'd go with looking for loose pipes first then try mini arrestors hopefully it fixes water closet as well. if not you could try changing fill valve before another mini arrestor
can't you control the master lav by closing faucet a little slower?
 

Gregg G

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Hi, Jeff - I will get down in the crawl space and start looking. I can close the faucets slowly, but they still make some noise. I hope it's just that I didn't do
a good enough job clamping things down - easy enough to put some more clamps. If not I'll try some mini arrestors near the end of the lines between the
lavatory faucets and shower. The only thing further is the Toto toilet about 8 ft away.
 

Gregg G

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So I figured out part of the problem was some broken clamps. When I installed the CPVC pipe I ignorantly used some of the "hammer-in" with
plastic clamps. They turned out to be very "non-robust", ha, ha! I removed all of them and went to steel plumbers tape, with a little piece of
pool-noodle style pipe insulation under the tape. Seems to be 1000% better! The clamps fixed 90% of my problem. The last issue is the
shower in the master bath. It's the "highest" pipe and always has a bit of hammer.

Just to be clear - whenever I flush the toilet in the Master Bath there is always a hammer in the shower pipe. I can shut off
the shower faucets and lavatory faucets slowly to almost completely reduce the hammer, but if I shut the supply to the
toilet very much, it takes forever to fill (and still doesn't completely eliminate the hammer).

I'm going to put in an arrester on both the hot and cold right before it goes through the floor (that's about as close as I can get).
I guess I should have put them in the shower wall near the valve when I was building, but I didn't expect to have this problem.
Anyway, any opinions on hammer arresters? In the laundry room I used the Sioux Chief mini-resters with the 90 deg angled
hose connections. They seem to work fine. Is there any real difference in the 1/2 vs 3/4 for a small residential application like
this one? Is it advised to go to the larger 3/4 mini-rester, or even the 3/4 "commercial" which seems to have quite a bit larger
chamber?

Thanks for your input!
Gregg G.
 

Jeff H Young

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not sure I've found sometimes a really bad water hammer doesn't go away adding a hammer arrestor.
I would think a 1/2 inch be ok though
 

Reach4

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Just to be clear - whenever I flush the toilet in the Master Bath there is always a hammer in the shower pipe.
One bang as the toilet stops filling? A water hammer arrestor should be able to fix that.
 

Jadnashua

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Many, but only those made in the USA (I think) Toto toilets tend to use a Korky fill valve. Those tend to not create water hammer. The newest toilets, especially those that flush with less than 1.6g use a different fill valve. Some valves tend to close fast, creating that hammer.

Is it just one bang, or a series of them?

WIth a well, you probably don't have excessive water pressure, but high water pressure can cause a water hammer to show up where it normally wouldn't otherwise.

By partially shutting a supply valve, you'll end up with less volume (weight and speed) of the water flow, and that might be enough to hide a hammer.

The pressure tank should help minimize any thermal expansion that could otherwise, raise the pressure until a valve is opened to relieve it. Otherwise, an ET might be called for, but not with a typical well system.
 

Gregg G

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Hi, everyone - Thanks for all your kind input! I think I found out what the problem is, but I don't think I can easily fix it.
As I mentioned, some of my supply pipes were rattling around a bit from inadequate clamping (plastic ones failing). The
sound I'm hearing at the shower is just like the sound I heard from the loose pipes...

I think I made a rookie mistake when I installed the shower valve. I don't remember exactly, but my guess is I didn't
do an adequate job of clamping the supply lines from the floor to the valve and what I'm hearing is the supply line
bouncing around just a bit. Unfortunately, I don't have access to the supply lines. One side is tiled in on the shower
side, and the other side of the wall butts up against the vanity. In the off chance that there is a little room around the
valve, I'm going to remove the handle and valve cover to peek inside and see if the rattle is coming from close to the
valve. If there's any access, I could try to put in a spot of expanding foam. Otherwise, I guess I'll just have to live
with the slight bump.

The toilet is a Toto, and it does have a Korky valve. I shut off the supply valve about half way, and that did reduce
the noise significantly - the toilet took about twice as long to fill, but that's probably okay.

Thanks for all the help!



on the shower side)
 

Gregg G

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Okay, I checked the valve body. I put in a couple of pieces of foam insulation on both sides
where I could reach in. The sound is definitely coming from the supply lines between the
floor and valve body - but I'm not sure if it's the pipe tapping against the studs, or if it's
inside the pipes. I guess I'll get a couple of the hammer arresters and see if they help.
Since the "flow" it's stopping is relatively small, I guess I'll try these 1/2" mini-resters.
I would try the next size up "hydra-resters", but it seems like Covid has made them scarce
and they're not due in stock for about a month!
 

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Reach4

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Is your symptom one bang heard near the shower piping only as the toilet stops filling?
 

Gregg G

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Hi, Reach4 - No, it's more of a "tap-tap-tap" when the toilet stops filling, or if I shut off the lavatory faucet quickly.
Not just one "bang". I put my finger on the pipe at the valve, and I just can't tell if it's inside or outside of the pipe.
 
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