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...