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Water hammer (I think) when turning on system

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secutanudu

Active Member

Posts: 36

Location: Guilderland, NY (Near Albany)

1

Tuesday, June 9th 2009, 5:29am

Water hammer (I think) when turning on system

I finally got my valve box and a zone installed (with only two heads so far). Whenever I turn the system on, either with the timer or manually opening my Master Valve & Zone Valve, the entire manifold gives a quick "jerk" and moves sharply, and also makes a noise. Is this water hammer?

I am afraid that if this happens every time a valve opens the manifold will eventually lose a seal, or worse a pipe will crack. Do I need a water hammer arrester in the copper area before I convert to PVC (maybe just after the backflow preventer?) or is there something else going on that I need to fix?

Incoming pressure to the master valve is 150 psi. I am using a Hunter ICV Valve with the AccuSet pressure reducer. I am reducing the pressure to about 70 PSI for use by the zone valves.

Thanks.

HooKooDooKu

Supreme Member

Posts: 683

2

Tuesday, June 9th 2009, 7:54am

150 PSI is way too much.

The suggestion at www.irrigationtutorials.com is to install a pressure regulator (back in the copper section of the pipe) when pressures are greater than about 80psi.

secutanudu

Active Member

Posts: 36

Location: Guilderland, NY (Near Albany)

3

Tuesday, June 9th 2009, 8:26am

I know 150 is too high, that's why I am using the ICV valve with the pressure reducer. According to hunter, this valve can upwards of 200 PSI and reduce it to anywhere from 20 to 90.

Shouldn't this work ok?

Wet_Boots

Supreme Member

Posts: 4,102

Location: Metro NYC

4

Tuesday, June 9th 2009, 12:38pm

You are not reducing any of the water hammer the plastic valve is receiving. Do yourself a giant favor and install something like a Wilkins BR4 pressure regulator at the point of connection for the system. Let the hammer forces go no further than the brass PRV. You can set its outlet pressure to whatever works for you.

secutanudu

Active Member

Posts: 36

Location: Guilderland, NY (Near Albany)

5

Tuesday, June 9th 2009, 12:53pm

Quoted from "Wet_Boots"

You are not reducing any of the water hammer the plastic valve is receiving. Do yourself a giant favor and install something like a Wilkins BR4 pressure regulator at the point of connection for the system. Let the hammer forces go no further than the brass PRV. You can set its outlet pressure to whatever works for you.
Problem is I had a plumber do the inside work for me...I am not so skilled at soldering, etc.

If I leave it how it is, what is the worst thing that will happen? I have to replace the ICV valve eventually?

Edit...now that I think about it, wouldnt the water hammer be occuring when the ICV valve opens and hits my zone valves? There is constant pressure on the ICV valve since it's the first valve in the system. The output pressure of that valve is set to 70 psi, so i would think the water hammer is happening when the Master valve opens and slams against the zone valve at 70 psi, just before the zone valve opens. Am I thinking correctly?

This post has been edited 1 times, last edit by "secutanudu" (Jun 9th 2009, 1:30pm)

Wet_Boots

Supreme Member

Posts: 4,102

Location: Metro NYC

6

Tuesday, June 9th 2009, 9:06pm

You are not thinking correctly. Get the plumber back and install the BR-4 (I recommend that particular model because you can set its outlet pressure beyond 100 psi if need be)

HooKooDooKu

Supreme Member

Posts: 683

7

Wednesday, June 10th 2009, 11:30am

Logically speaking, the ICV valve is a valve with a pressure regulator after the valve. That means when the valve opens, the pressure regulator gets slammed with the 150psi. The ICV just makes sure those high pressures do no go out to the latteral lines. In the mean time, your valves and the entire manifold, plus all the PVC pipe running to the manifold are under that constant high pressure. The worst case senario is that something in all that plasitc busts and you don't find out about it for several days after which you have a large water bill and possibly lots of errosion. You might think you would immediately notice errosion, but in a worst case senario, the water could wash away underground dirt sort of creating a sink hole when the surface finally collapes.

You might not have to have a plumber do the work of installing a brass pressure regulator back at the brass pipe. For one, that should be AFTER the backflow preventer, and very few local building codes require plumbers AFTER the backflow preventer. So if you can find a friend that is handy at soldering, you can get them to do it.

Alternately, you can learn to solder. For a beginner, it's easier to learn using MAPP gas (yellow cylindars) rather than propane (blue cylindars) because it burns hotter. It lets you get in and get things heated up fast. With propane, unless you have an adjustable tip to allow you to focus the flame, it becomes too easy to burn off the flux before the pipe gets hot enough to melt the solder. But with MAPP gas, it gets hot enough that once the flux starts to burn off, the pipe is almost instantly hot enough afterwards. For less than about $50 you should be able to get a MAPP gas canister, a torch (I like the ones with the trigger that lights it for you rather than you having to light it yourself), some solder, flux, a pipe cutter, and a test section of copper pipe and a few fittings.

secutanudu

Active Member

Posts: 36

Location: Guilderland, NY (Near Albany)

8

Wednesday, June 10th 2009, 12:03pm

Thanks for the responses.

I can sort of solder, I have all the stuff for it (MAP gas, solder, flux, etc), I just hate to cut into all the nice stuff the plumber already did for me.

Thanks for the advice. What you said makes sense.

Wet_Boots

Supreme Member

Posts: 4,102

Location: Metro NYC

9

Wednesday, June 10th 2009, 6:24pm

You can simplify the 'cutting in' of a pressure regulator by purchasing a "double union" type, and the union ends could be threaded or sweat.

secutanudu

Active Member

Posts: 36

Location: Guilderland, NY (Near Albany)

10

Thursday, June 11th 2009, 10:56am

Re-reading this thread, I realized that I did not properly describe how my system is set up.

Basically...the ICV valve comes before the manifold and the rest of the valves (Hunter PGV Jar-top), so the only plastic parts under constant pressure come before the ICV valve, which is simply a couple feet of PVC pipe and a few fittings. There is also one 90 degree manifold elbow and one schedule 80 PVC nipple just before the ICV valve.

Should 150 pounds of pressure slamming into a pressure regulator be OK? Isn't that what it's for?

I guess getting a threaded regulator in after the backflow device would be manageable, I am just trying to decide how necessary it is (the system cost me much more than I have expected already).

Thanks for all the advice.
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