Pipes knocking when sprinkles come on

[chayfordaz]

When my sprinkler system kicks on there is a really bad knock in the rest of the house's pipes. Sounds like water hammer but it keeps up as long as the sprinkler valve is on. Could the sprinkler valve itself be the cause?

 

[camaroderrick73]

No. More than likely its just the diaphragm in the sprinkler valve that's turns on or shuts off makes the sounds if hammering.. Only way I've resolved these issues it's by installing a check valve before the sprinkler line so the vibrations don't go back into the house.

Oh and was this installed at a hose bib a landscaper tee'd into Installing a sprinkler line? I see this many times ....