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View Full Version : Hi guys, the pest is back. Water hammer problem


jingles
05-04-2006, 09:43 PM
I installed three rainbird valves to replace toro valves. The toros never did this. The rainbirds work fine. I have a bad problem with water hammers on all three. This occurs only when they close. I had a repairman install a new back flow unit. Its a febco, this one I believe.... http://onsmartpages.com/kelleyslawnandirrigations/pages/store/skudetail.nhtml?profile=productsservices&uid=10190&catuid=10113&returnURL=http%3A//onsmartpages.com/kelleyslawnandirrigations/productsservices/category.nhtml%3Fcatuid%3D10113
Any suggestions on how to cure this. Thanks for your help and patience.

bdb
05-04-2006, 10:17 PM
The water hammer is caused by two things the velocity in the pipes...exceeding the recommended 5 feet per second and the valve operation. I know that Hunter's has a delayed or slower closing diaphragm's which helps eliminate the problem. Most other valves are instant on/off. Toro's flow pro's close slow and after they have been "broken in" and don't close all the way and weep.

DarkLotus
05-05-2006, 05:49 AM
Hunter, Nelson and Toro valves I believe are slow closing. I would never install a valve from either company though. If I have the water hammer hit after each zone, I would throw on an inline water hammer reducer. It costs between 5-15 from the supplier and I still keep the quality from the valves.

DanaMac
05-05-2006, 08:47 AM
RB Dvs do shut down hard. I have "fixed" this once by changing to DVF and cranking the flow 2-3 times, and they didn't shut down as hard. Not saying it will do that for you. Just saying.

Also check your pressure. High pressure can give loud clunking at shut off. Check and see if your pipes are not secured in the basement - if they are set up this way. Maybe they rattle against a joist when they shut down.

jingles
05-05-2006, 08:52 AM
Thanks for the reply guys. I am going to buy a water pressure gage today and test the pressure. My water company had told me before that my area is prone to high water pressure and had installed a pressure reducer on my main line, that is adjustable. Also, DANA, what is a DVF .....DarkLotous I will look into the water hammer device. Can I install this, or should a pro. I am hoping my water pressure is to high, and I can simply adjust the valve to correct this. What should house pressure be to be in normal operating range. Again thanks for your help and patience all.

DanaMac
05-05-2006, 09:12 AM
When you said you installed Rainbird valves, I assumed DV series. DVF is the DV valve with a flow controll. A knob on top that controls how much water flows through the valve.

http://rainbird.com/pdf/turf/ts_DV-DVF_barb.pdf

Ground Master
05-05-2006, 12:53 PM
Jingles- Try using a rainbird pga or peb valve. They cost more but are slow closing. Try one for the last zone and see how that works for you.

Dirty Water
05-05-2006, 08:37 PM
Before you replace the valves you just spend tons of time installing, buy one Rainbird DVF, and change the bonnet on your Rainbird DV to the DVF bonnet (the bodies are the same).

Try throttle down the flow control and if it helps, change the rest.

Rainmaker
05-05-2006, 09:43 PM
according to Rain Bird when this happens after a winterization you should manually open the valves from the bleeder screw to releive any air trapped in the valve I have ran accross this problem a number of times and 9 out of 10 times it worked

maintenanceguy
05-06-2006, 07:00 AM
Water hammer is caused by the heavy slug of water moving through in the pipes slamming against the valve. Water is heavy and incompressable. It's like throwing a concrete block against a tree.

Any plumbing supply will have a "hammer arrestor". This is a small air chamber that gets plumbed into the line leaving the house. The air chamber will absorb the energy of the impact. The more water volume you have in the line, and the faster it's moving, the bigger chamber you will need. Most are about 6" in diameter but you can get them much larger.

jingles
05-06-2006, 08:35 AM
Hey guys thanks for all the great replies. Just wanted to update everyone. Yesterday I bought one of those watts water pressure gages. I am kind of surprised at the reading. I hooked it up to my hose bib, and the reading was nearing 100 lbs. As others had mentioned this is way above normal. I am kind of doubting that it could be that high. Its 3/4 inch's service off the street, but where it comes into the house, it had been one inch service. The water company reduced it when I moved it, saying 1 inch service would cost more for water service. Any way when they reduced the pipe, they put a Watts pressure reducer on the line, http://www.watts.com/prod_images/hi-res/25AUB_Z3.jpg
Well I tried turning the screw in and out, didn't do jack!. Someone else here suggested checking for lose pipes. The main line that the sprinkler line runs off of was not anchored at all, just in place with hangar type thing. I bought a dozen pipe anchors at Home Depot, and installed them. This really knocked out the noise. But 100 lbs pressure seems really high, unless the gage was off. So I think the pressure reducer is not working, or I am not adjusting it properly. I may try a different pressure gage reader today. Again thanks all :)

jingles
05-06-2006, 08:44 AM
I also did this, and it may have helped alot. As the noise is essentially gone, well it was yesterday. See what happens today...thanks according to Rain Bird when this happens after a winterization you should manually open the valves from the bleeder screw to releive any air trapped in the valve I have ran accross this problem a number of times and 9 out of 10 times it worked

PurpHaze
05-06-2006, 10:03 AM
according to Rain Bird when this happens after a winterization you should manually open the valves from the bleeder screw to releive any air trapped in the valve I have ran accross this problem a number of times and 9 out of 10 times it worked

Good thought. This will occur even with slow closing valves that have just been installed. We use Irritrol Century Plus valves and even these will hammer a little for the first couple of times they're used unless some measures are taken. Example: Yesterday I replaced a 2" valve (actually a top end job) that had started to experience diaphragm weep-by. This system has a booster pump installed on the field system to augment domestic pressure. I always shut down the flow control stem before I turn the BF back on so I can check to see if there are any leaks prior to testing the valve. Then I open the FC about half way and manually actuate the valve a couple of times. The valve opens and closes properly without any hammer and kind of gets the diaphragm juiced. Then I open the FC completely and fire the valve via remote and it performs without any hammer at closing.