Water Hammer Arrestor

[BeezFun]

I've had a bad water hammer problem since I installed a few automatic horse waterers that have spring actuated valves. I have a 200' run of 1" plastic water line out to the barn, this has caused a really bad water hammer problem in the house every time the horse takes a drink. When the horse finishes drinking, the valve snaps shut and causes a pressure wave that creates water hammer.

So I gritted my teeth and did what I should have done when I installed them and installed two water hammer arrestors at the end of the 200' line. Of course this required digging a hole big enough to bury the horse in. Either arrestor is sized to take the whole pressure wave, if one fails the other one will be adequate. They cost about $45 each. After installation I can't hear anything in the house when the valves are actuated by the horses, so mission accomplished. In the attached photo the water hammer arrestors are the copper things on the right, the 200' line exits to the left in the photo and goes up to the water source at the house.

 

[mrmikey]

I thought they had to be vertical so the air stayed trapped?
Not being picky so please don't take offense If they're buried, I would have put them in some kind of sump to keep the earth off the copper. My not be necessary but.....Mike

 

[BeezFun]

I thought they had to be vertical so the air stayed trapped?
Not being picky so please don't take offense If they're buried, I would have put them in some kind of sump to keep the earth off the copper. My not be necessary but.....Mike

These have a piston in them, the air is in a sealed chamber, so they can be installed in any position. That's why they're so expensive.
Copper is fine underground as long as the proper backfill is used around it to exclude organics and differential contact with corrosive soils. I plan to use washed sand.

 

[s219]

It's amazing how many fixtures have "bang-bang" valves. Things would be a lot easier if softer valve closures were designed in. It's a real travesty when valve closure is electronically controlled, since there's no reason they can't program in softer closure behavior.

I used to have a big water hammer problem with an irrigation system, which would send a shock wave through the house every time a zone's valve closed. It was enough to overcome all the toilet float valves, so there would be a mini-flush on three toilets every time! I later upgraded to a different irrigation controller which opened the next zone's valve before closing the previous zone, and that solved the problem.

Our washing machine (Maytag Atlantis) is the worst offender. Both hot and cold valves snap shut real abruptly. I had to put arrestors on both lines.

 

[Canada_CT230]

I would at least wrap them in a bit of landscape cloth. It is some protection against direct contact and would keep them clean if you ever needed to get back there.

 

[jonyyuma]

I had plenty of room over the hot water heater so i put two long pieces of CPVC up the wall and capped them..They are vertical so the air does the work..Problem solved for us..

 

[Egon]

I had plenty of room over the hot water heater so i put two long pieces of CPVC up the wall and capped them..They are vertical so the air does the work..Problem solved for us..

That type of arrestor may not be to code in many areas.

 

[BeezFun]

That type of arrestor may not be to code in many areas.

You're correct, the old air tube risers seem to be against code in a lot of places, including around here. The only problem I've ever had with them was getting water logged, but you could just drain the system and refresh them. There must be some other problem that has caused them to fall out of favor, or maybe there's a political lobby for arrestors.

 

[BeezFun]

I had plenty of room over the hot water heater so i put two long pieces of CPVC up the wall and capped them..They are vertical so the air does the work..Problem solved for us..

I have risers in the house too, but that's at the wrong end of the line in this case. When the water is traveling down that line to the barn and suddenly stops, the energy needs to be absorbed at the far end of the line. Other problem with putting a traditional riser on this line is the end of it is at the low end of the system, so there's no way to drain it if it ever gets water logged.

 

[955er]

What kind of waterers did you install? I am getting ready to put in a single ritchie unit. I have about 350 ft of 1.5 inch, tapped between the well and tank out to a frost-free. I am planning to tee off of that line, reduce to size, and install the shut off valve. I have had no problem with the frost free fixture provinding any issues, nor have I had any issues with hammering at the well tank.

I guess I am wondering if I need to install one of these...

 

[BeezFun]

What kind of waterers did you install? I am getting ready to put in a single ritchie unit. I have about 350 ft of 1.5 inch, tapped between the well and tank out to a frost-free. I am planning to tee off of that line, reduce to size, and install the shut off valve. I have had no problem with the frost free fixture provinding any issues, nor have I had any issues with hammering at the well tank.

I guess I am wondering if I need to install one of these...

I installed Drinking Posts, I posted this thread on it last fall.

You won't have hammer with a manually operated valve because it closes so slowly (relatively speaking). I'm not familiar with Ritchie units, but if it has a spring or solenoid operated valve, you'll need an arrestor. The issue is how fast the valve closes: if it closes really fast then it creates a shock wave that causes the hammering. If you're T'ing off an existing line, I'd put one larger arrestor at the end of your longest run, and a smaller arrestor at the end of the run for the waterer. The issue is that the column of water moving down that long length of pipe has to stop suddenly so the best place to absorb that shock is at the end of the long run. If you can't get to the end of the longer run, just put a large one by the arrestor and hope that does the trick. I chose to put in two instead of one because they're cheap compared to the labor of digging the whole thing up if one fails.

 

[Egon]

There must be some other problem that has caused them to fall out of favor, or maybe there's a political lobby for arrestors.
/QUOTE]

Dead water and bacterial growth.:thumbsup:

 

[Sterff]

I would protect them or mark the location. WH arrestors do not last forever. I have replaced them after 2 years already.

 

[BeezFun]

I would protect them or mark the location. WH arrestors do not last forever. I have replaced them after 2 years already.

I've got a survey I keep updated with the location of everything, so I know right where it's at. I also throw a piece of pvc a few inches above it so I hit that first with the shovel.

I bought commercial grade units from Watts, hopefully they'll last longer than the stuff they sell at the big box stores. If you're replacing them every 2 years they might be getting damaged by soldering heat during installation, or if they're even slightly dented or deformed it doesn't allow the piston and oring to seal properly.

 

[Sterff]

I've got a survey I keep updated with the location of everything, so I know right where it's at. I also throw a piece of pvc a few inches above it so I hit that first with the shovel.

I bought commercial grade units from Watts, hopefully they'll last longer than the stuff they sell at the big box stores. If you're replacing them every 2 years they might be getting damaged by soldering heat during installation, or if they're even slightly dented or deformed it doesn't allow the piston and oring to seal properly.

Im talking about Zurn WH arrestors, and I assure you they are installed properly, Im a journeyman plumber. Depending on how often they are used they can wear out sooner than you would think.

 

[Kays Supply]

Beezfun, where is " around here " ? I am in S Ilinois and installing 96 riser type arrestors tomorrow. I have passed inspection on 5 8plex apartment buildings at this site since Jan 1, 2012.

 

[BeezFun]

Beezfun, where is " around here " ? I am in S Ilinois and installing 96 riser type arrestors tomorrow. I have passed inspection on 5 8plex apartment buildings at this site since Jan 1, 2012.

DuPage county, next county west of Chicago.

 

[jonyyuma]

There must be some other problem that has caused them to fall out of favor, or maybe there's a political lobby for arrestors.
/QUOTE]

Dead water and bacterial growth.:thumbsup:

Can you explain this please...They WERE Legal here, but haven't had occassion to check the regs? yes, I realize you cannot put them in a ditch. I have had a watts before...Commercially they are putting a captive air bladder into the lines on this building..about 3 gallons.

 

[BeezFun]

Im talking about Zurn WH arrestors, and I assure you they are installed properly, Im a journeyman plumber. Depending on how often they are used they can wear out sooner than you would think.

Interesting design, they use a stainless bellows to isolate the air chamber from the water. I'm guessing they're really expensive. I've never understood why they don't just use a shock absorber mechanism like cars use in these things, then you don't have to worry about leaking air.
The water itself could be the fluid, the perforated disk would be forced through the water and returned by the spring. I installed two chambers to hedge my bet against a premature failure, maybe I should have installed more extras. Once I build my new barn I can move the arrestors above ground so they'll be easy to get at if they fail.

 

[Egon]

The upright air pocket piping does not have water through flow. There are fears the stagnate water may allow bacteria to multiply and eventually contaminate the water line.

at one time they were probably manditory in the regulations.