Who else has seen this? I would like to hear the reason as to why you think they are in the valves always closest to the PVB.. my thoughts: Bad Boiler drains > high air pressure and constant water pressure over the years> screw falls out right into my flow pro's/ irritrol Jartops,1 inch. what do you think? Also, What is you first thought when you see an old controller (lets say a toro vision or a weathermatic) with the 1 and a half amp fuses? And said controller keeps popping fuses...What is your next step... I know mine, and I also know how i found the problem...What would you all do in a situation like that? con first or field first?