Does anyone know if this will work in the Febco 805Y, which has been discontinued?

@piplipton thanks for this comment. I had just installed the blue heron and had your same issue. I was about to return the item and buy the entire febco unit but then ran into this comment. Worked perfectly after letting the pressure build up a bit.

This is everything you need to replace the plastic bonnet and poppet. Those are the parts that break consistently.

In reply to myself...Closing the valve on the "out" side allowed it to build up enough pressure to push the poppet up against the bonnet. Opened the "out" side valve and have a working sprinkler system again.

I picked one of these up for my Febco 765 but it's not working as expected. When the Bonnet Assembly is screwed all the way down into the housing, it's not seated against the Poppet so water still flows out the canopy. Looking at my original (broken) Bonnet/Poppet Assembly there's an adjustment screw that looks like it's supposed to correct this issue that isn't on the Blue Herron unit.