Water hammer

**valveman** · 05-24-2012, 06:36 AM

You still don’t understand. You need to remove that check valve, not replace it. Just put a union or a telescoping repair unit in if you can move the pipe.

Now to the reason your check valves are failing…. the pump is cycling on and off while you are irrigating, except for that one properly sized zone. When the pump cycles on and off, the check valve(s) are slamming open and closed repeatedly, until they fail. Cycling on and off is also causing abuse to everything else in the system. The water hammer from the failed check valves is just the first thing to surface. The pump will be the next thing to fail.

You either need to size all your zones like zone #2, so that the pump stays running, or install a Cycle Stop Valve to make the pump match the zones.

**JoeyH** · 05-25-2012, 08:09 PM

thanks Valveman, I did not see your reply till now, my Local sprinkler store, suggested that I raise the cut in pressure to 35lbs, and that stopped the cut in water hammer, I did set the cut out pressures higher, and it did stop pump from cycling, tank pressure would not go hig, so ok, I'm going to remove Horizontal check valve, (I made the mistake and typed Vertical on last message), and if cycling does continue, I will install CSV, hopefully by removing check valve the hammer will stop, I will let you know either way.
Thanks again

**traveller** · 05-26-2012, 12:04 AM

Just out of curiousity, how far is your pressure switch from your bladder tank?

**JoeyH** · 05-26-2012, 07:17 PM

Originally Posted by traveller

Just out of curiousity, how far is your pressure switch from your bladder tank?

About 24 inches of pipe.

**JoeyH** · 05-27-2012, 11:30 AM

I removed check valve, spring was broken and it was faulty, I replaced it with telescopic coupling, after I waited an hour for PVC glue to set, I turned pump on, no water hammer is heard when on nor off, that resolved, BUT, now after pressure tank fills, water is running out of it, all valves are closed and irrigation system is turned off, I can,t see anywhere that water might be leaking, I believe that it is going back down to well.....???????

Pump comes on till tank is full and shuts off properly, but it is now continually cycling, system was turned on before check valve was removed, and it was holding water in pressure tank, all that I did prior to removing check valve was to turn off pump switch.

**cacher_chick** · 05-27-2012, 12:01 PM

The problem is that the check valve in the pump has failed. The water hammer was a symptom.

The pump needs to be pulled.

You get to decide whether to replace the pump or just install a good quality check valve in the output pipe, directly above the pump.

**JoeyH** · 05-27-2012, 02:01 PM

Because of finances, I'm in no position to pull out the pump, I may just have to install another check valve where the other one was, and hope that it holds me for a while.

**JoeyH** · 05-27-2012, 02:13 PM

If I have to pull pump up, I might as well replace pump, and check vave, it was installed in 1990, and instead of metal pipes, I'll go with polyethylene, I have no idea of how deep well is, I'm sure that the deeper it is the more cost in labor it will be to pull.

**LLigetfa** · 05-27-2012, 03:03 PM

Originally Posted by cacher_chick

The problem is that the check valve in the pump has failed. The water hammer was a symptom.

The pump needs to be pulled...

A checkvalve holds best if it has a constant pressure against it. For some unknown reason, some folks think it is a good idea to also install a checkvalve topside. The problem then is the topside one doesn't allow constant pressure to be applied to the one in the pump, causing it to eventually leak down, creating a vacuum at the top. The vacuum causes water hammer on start which eventually damages the topside checkvalve.

Hammer on stop would suggest both are now bad but replacing just the topside one won't prevent hammer on start. The hammer will eventually damage the topside one again.

**ballvalve** · 05-27-2012, 03:34 PM

If you go on the cheap, be sure and spend for a BALL CONE spring loaded check valve. With the high cut out, you get a free CSV and the quick closing ballcone will likely reduce hammer much. Better save up for a pump though.

http://www.grainger.com/Grainger/wwg...rue&sst=subset

**JoeyH** · 05-28-2012, 08:32 PM

I installed a check valve where the faulty one was, no more water hammer, and to top the cycling I set cut off pressure to 70lbs because that's what I needed in order to stop zone #4 from cycling the pump, all other were not cycling somewhere between 55 and 60lbs, I hope this holds me over for a while, the bladder pressure tank is rated to 100lbs of pressure, is this going to affect or damage any other parts of the system?