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The last 10 posts

Wednesday, October 11th 2017, 6:18am

by blizzard123 (Guest)

Possible solution


Sorry for bumping a very,very old thread, but I thought a possible solution to this is best
placed here and perhaps others can find it educational, especially if they experience something similar.

We too have some kind of a sound in pipes for about a second(a vibration of sorts) when water
switches from zone 2 to zone 3. But only when it changes zones then and there. What I have discovered was that when zone 3 opens, water 'back flows' slightly from the water main line that comes 'after' the sprinkler, perhaps indicating there might not be enough water for that specific zone because too many heads open at the same time
creating a sudden need for more water.

Now, what prevented this before? A water softener, one which I recently put on bypass because it was
creating low pressure. The water softener was functioning unintentionally as a back flow preventer.

You can check if this is the solution by closing the valve 'after' the sprinkler connection and see if the the sound occurs again when sprinkler is turned on. But also important to check water pressure near the sprinkler line to see if it is within range.

Hope this helps.

Tuesday, June 19th 2012, 10:46am

by mattb2003

Thanks again for your help. One thing I did notice is that since the new pressure tank was installed, the water pressure to the sprinkler system seems to be higher. I did a "test" last night by turning the system on zone 1 and let it run until right before the switch to zone 2. Before the switch, I turned a few faucets on and ran the water inside the house while it switched from zone 1 to zone 2. No banging, thumping, or loud noises of any kind (and I hadn't run the sprinkler system since the day before, so it should have made some noise). It seems that if water is running in the house, it doesn't have the problem. I'm going to check again tonight to verify that is the case.

My thoughts are the same as yours - throttle down the pressure to zone 2 with a flow control bonnet. I'm thinking that the alternative is to check pressure before the PRV to the house to see what the incoming water pressure is. Since we have 2 PRV's (one before the water meter, and then one after the sprinkler cutoff but before the rest of the house) I can adjust the incoming water pressure via that first valve. Is there anything wrong with this approach? I'm not sure what the standard pressure range should be on the incoming line.

Monday, June 18th 2012, 10:37am

by Wet_Boots

Since a PRV greatly inhibits backwards flow, a pressure tank downstream shouldn't make a difference. If the PRV was stuck open (not likely) then the pressure tank would come into play.

The easiest no-plumbing-required fix you can try is the flow control bonnet. Once a zone valve is throttled down, water can't rush through it like in a standard valve, and that can be enough to stop the banging.

Monday, June 18th 2012, 10:09am

by mattb2003

Yes, we are on a slope, so that's definitely possible. I don't ever remember this happening when we turn the sprinklers on for the first time when the season start (the system is drained for the cold winters).

Is it possible that since the expansion tank was replaced there's somehow a change in pressure to the sprinkler system that could be causing this and lowering the pressure would fix the problem?

We have two PRV's attached to the system. One is before the water meter (our meter happens to be in our basement - not sure why they did it this way) and one after the meter and after the cutoff to the sprinkler system, but before the pipe leading to the rest of the house. Since we didn't hear this banging before, my only guess is that it has something to do with the expansion tank (the plumber didn't touch anything else, at least as far as I know).

Monday, June 18th 2012, 9:24am

by GatorGuy

"there was a loud bang and then a loud thumping for a about 7 seconds or
so (seemed like forever) until the system filled and the water flowing
out of the sprinklers."
" It is the worst whenever zone 2 comes on for the first time after not using it for a while"
"...about an hour later, no bang or thumping..."

Is your yard sloped? Could the water in the zone be draining out through the low head leaving most of the zone empty?
The water rushing to fill the pipes might explain what you hear. It can take hours for this to happen so turning it on an hour later meant some water would still be in the pipes.

Sunday, June 17th 2012, 8:59pm

by Wet_Boots

Unless you have some crap make and model of zone valve, you can get a flow-control bonnet for it.

Sunday, June 17th 2012, 6:46pm

by mattb2003

Well, apparently our valves don't have flow control, so I guess we'll have to look into other solutions. Maybe replace the valve or put a PRV before the sprinkler system. If there are any other ideas, I'd greatly appreciate it. Thanks again for all of the help so far!

Sunday, June 17th 2012, 4:35pm

by mattb2003

Thanks for the responses. I'm pretty sure it's when zone 2 turns on. I stood down in our basement during the switch as I thought it was a problem with the shutoff of zone 1. Zone 1 shuts off and there's very little noise. About a second later, zone 2 comes on and as soon as the water starts flowing to zone 2, it makes the thumping noise (and can last quite a few seconds). I'll check both though a the controller to see. I'll also see if there's a way to tone down the flow of zone 2.

Thanks again for the assistance!

Sunday, June 17th 2012, 10:39am

by mrfixit

Are you sure it's zone 2 causing the problem? Could it be zone 1 when it shuts off?
Try turning on and off zone 1 and zone 2 manually from the controller a few times to see..

Sunday, June 17th 2012, 9:45am

by Wet_Boots

throttle down the flow control of the zone 2 valve