Main Water Valve is shooting water

I just purchased a new house with a Hunter Pro-C system. I had included a request that the unit was winterized in the purchase of the house.

I am trying to set things up and when I turn the water valve on, there is water shooting out of the top of the main water valve (there is a black plastic ring on the top). This happens if the Hunter system is on or off. So - I have the main to that pipe permanently off and can't use the system until I resolve this (and the local landscaping guys don't seem to return calls...)

Any advice would be MUCH appreciated!

What do you mean by "main water valve"? Is water coming out of your vacuum breaker? (See attached sketch).

Maybe the pressure vacuum breaker was partially disassembled during winterizing and you need to put it back together. Just a guess.

Yes - it is coming out of the top of the plastic piece in that vacuum assembly. Thanks for the help.

Winterizing may not have been performed, or maybe a shut-off valve was leaking. Continuous water from the top of the Pressure Vacuum Breaker may indicate broken plastic parts.

leak

It froze and broke the inside piece. Usually you can repair it with a new cap and float, but if the body was distorted you need a new valve.

Thanks everyone. I will check it out. Appreciate it.

Like to see some follow up here, as I suspect that freeze damage is not the case. I get these calls every spring from new homeowners.

Close all the valves on the PVB before opening the main supply valve.

Open the upstream valve (closest to supply valve) first. Quickly. You should hear a slight pop. This is setting the spring and rubber seat. If the second and downstream valve is open, it is not providing enough back pressure to seat the ring, and water just dumps out of the PVB.

Open the down stream valve slowly, as not to cause a low pressure state and reopen the dump valve. By the way, you should have one of the lateral valves open to allow the compressed air to escape the system.

When the pressure equalizes against the heads, open the valve all the way.

You should be set til fall. If you are using the valves on the PVB to shut off the system, use the down stream valve. Or you could have the low pressure - filling the lines - dump valve opening problem again.

Same problem here

I have a Hunter Vacuum Breaker as you show in the diagram. I have replaced that guts and tried opening the valves in the sequence you indicated. Still have water coming out the top. Any suggestions, at $100+, I hate to have to replace it.

Thanx