Dbowers question regarding humming noise

Hello,

Here is a pic of a boiler drain:


Here is a pic of an atmospheric vacuum breaker



I have seen both cause a humming noise on sprinkler systems.

If the boiler drain is the cause you will just need to make sure that it is closed ALL THE WAY. The one system I had seen was a boiler drain on the outside of the house, not even connected directly to the irrigation system causing a humming noise. I would just go around and make sure they are all properly closed even they looked closed give them a twist anyway.

If you have a boiler drain w/ an Atmospheric Vacuum Breaker on it causing the humming noise then try to remove the atmospheric vacuum breaker to see if that is the source of the noise. I had seen a system this spring with a AVB causing the noise, after removing the AVB the noise stopped. An Atmospheric Vacuum Breaker is a backflow device and should be installed on certain applications. If installed properly they will not be easy to remove and you might just want to remove the entire boiler drain /AVB combo and insert a threaded plug to test.

I hope this helps you. If not I will probably refer to my plumber and may have a few more questions. Either way please let me know.

Regards,

Bob