Is there a stand-alone float I can install after a Big Mouth?

Shalom

So over the past couple years I've replaced 3 of my four main vents with Big Mouths, the 4th one is on order today now that Amazon has 'em back in stock. I'm only a little nervous about the lack of a float, because there have been times in the past where the old-style fill valve on one of the boilers hasn't seated all the way and the boiler overfilled (no auto feeders here). Eventually that's getting replaced by a ball valve, But until then, I'm wondering if there's anything I can screw into the outlet that would pass air but block water. Or should I just run some PVC pipe from there to over the sink? (edit: would be simpler to just put an elbow and leave a bucket underneath, now I come to think of it. Which would work fine until the bucket overflows, I guess.)

ethicalpaul

I like your bucket idea (maybe with a moisture detection alarm) even better than a float because won't a float force the overfilled water to run upstairs to the radiator vents and spew water all over the finished flooring? (assuming single pipe)