Anti syphon valve- water spraying out

[Casond86]

So for the past few months we've occasionally had our auto fill system start spraying water from what I assume is the anti syphon valve. Can anyone explain why this may be happening? It seems to only do so when the pool is full, and even then it seems random when it actually does this. One thing I have noticed is that when I shut off the valve on the pool side of the anti syphon valve, it won't stop, but if I shut off the valve on the water source side, it stops. Any advice is much appreciated.

 

[Bperry]

So for the past few months we've occasionally had our auto fill system start spraying water from what I assume is the anti syphon valve. Can anyone explain why this may be happening? It seems to only do so when the pool is full, and even then it seems random when it actually does this. One thing I have noticed is that when I shut off the valve on the pool side of the anti syphon valve, it won't stop, but if I shut off the valve on the water source side, it stops. Any advice is much appreciated.

View attachment 520905

How old is the valve? Sometimes dirt can get in the fittings and not be able to close.

 

[HermanTX]

Welcome to TFP.
That part you have circled in BLUE is a relief pressure valve. It will release pressure from the system.
It is best you get the manual for that specific valve - it is called a Reduced Pressure Zone Backflow Preventer Assembly. Some call it RPZ valve for short. The mfg. Watts is one that I am familiar with.

 

[Casond86]

How old is the valve? Sometimes dirt can get in the fittings and not be able to close.

only about 8 months old.

 

[HermanTX]

only about 8 months old.

It is not uncommon for the relief valve to relieve excess pressure. However, the spring and diaphragm in the valve can break or tear and cause it to malfunction. If you show the top of the RPZ, you should be able to remove the top plate to access the relief valve. I am basing this on what I have worked on but your model may be different. Thus, try to find the model number and the manual. The valve to the left (closest to the main water supply) cuts off all water to the RPZ.

 

[Ahultin]

Looks to be the 3/4" Bronze RPZ (009M3QTFS). The instructions say this:
After initial installation, a discharge from the relief valve opening may occur due to inadequate initial flushing of pipe lines to eliminate dirt and pipe compounds. If flushing does not clear, remove the first check valve and clean thoroughly.
NOTICE
Periodic relief valve discharge may occur on dead end service applications, such as boiler feed lines or cooling tower makeup lines due to fluctuating supply pressure during a static or no flow condition. To avoid this discharge, install a spring-loaded rubber seated check valve ahead of the backflow assembly to “lock-in” the downstream pressure.