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PVB not working?

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outdoorjunkie

New Member

Posts: 7

Location: Houston

1

Friday, August 12th 2011, 12:28pm

PVB not working?

Hello All,

For a few days I have notice that if I have my water house in the back yard (only in the back yard) is turned on but closed at the hose side at the same time my sprinklers turns on it creates sort of a quick vacuum pressure making the spicket blow out water momentary (only a few secs) is this normal or is my PVB not doing its job?

TIA!

Central Irrigation

Supreme Member

Posts: 364

Location: Central Minnesota

2

Friday, August 12th 2011, 2:51pm

That rush of water is actually the PVB DOING its job.



When your sprinkler system turns on, it is demanding almost all the water your house can supply. This sudden drop in house water pressure actually will try to siphon water out of your garden hose. The PVB is in place to prevent any water from being siphoned back into the house. It does that by purging the water that is trying to re-enter the house.



Another scenario, is that your garden hose is at a higher elevation than the PVB.



Either case, your PVB is working properly.

This post has been edited 1 times, last edit by "Central Irrigation" (Aug 12th 2011, 3:02pm)

outdoorjunkie

New Member

Posts: 7

Location: Houston

3

Friday, August 12th 2011, 2:59pm

Quoted from "Central Irrigation"

That rush of water is actually the PVB DOING its job.
Ah! Thank you very much for the reply. So nothing to worry about :)

Again Thanks for the info.

Wet_Boots

Supreme Member

Posts: 4,102

Location: Metro NYC

4

Friday, August 12th 2011, 6:33pm

Something might be causing more of a pressure drop than usual, if this has not been seen in past years. Partially-closed valves upstream of a PVB, for instance.

outdoorjunkie

New Member

Posts: 7

Location: Houston

5

Thursday, August 25th 2011, 12:32pm

Wet_Boots,

Thanks for the reply. This is a new install and at most it has about 5 month... I did went to my neighbors who had hess professionally installed and it does the same thing. I talk to the builder in our neighborhood and he said that we have major pressure issues in our area.... That pressure was all ways lower than average...

Your thoughts?

Wet_Boots

Supreme Member

Posts: 4,102

Location: Metro NYC

6

Thursday, August 25th 2011, 3:36pm

If you have enough pressure to run the sprinklers, then you just live with the PVB burping water

M2inOR

Unregistered

7

Tuesday, September 13th 2011, 10:49pm

Stumped by PVB problem

I have a system that has been working fine for many years. 7 branches, huge yard. Problem free until recently.

When I turned on my system this year, I had problems with 2 branches of my system, where when either was turned on, the PVB opened after the branch filled and stayed open. It actually oscillated, causing water hammer throughout the house. If I manually turned the water on gradually using the shutoff valve before or after the PVB, I could avoid the oscillation and perhaps only have a slight burp.

System ran flawlessly for years.

My first thought was a defective PVB, so I replaced it with another Toro 53300 PVB. Easy to swap out, but the problem remained.

The branches with the problem have 4 or 6 Hunter rotating lawn sprinkler heads. They function OK.

So...

What might the problem be?
- have plenty of pressure
- all lines are 1" schedule 40
- all valves are working as expected
- no leaks that I can tell

After reading up on things, I see that some heads are now available with check valves at the sprinkler. Could it be that the lines are draining, sucking in air at the sprinkler heads and I am experiencing a type of water hammer due to water in the branches?

Any ideas before I bypass the PVB temporarily to see if there are other issues in the system?

Thanks in advance.

Mike


Mike

Wet_Boots

Supreme Member

Posts: 4,102

Location: Metro NYC

8

Wednesday, September 14th 2011, 9:21am

Do not bypass the PVB - the water supply is more important than your lawn. Make dead certain that there are no partially-closed valves upstream of the system.

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