This Watts 9D-M3 Backflow Preventer Valve feeds water into our furnace, provides an overpressure relief, and prevents heating loop water from re-entering the potable water supply.

The vertical pipe leads downward near the floor, underneath which sits the small plastic bucket I provided to catch the occasional drip. Recently we had an all-hands scramble to soak up a pool of water spreading across the floor from the overflowing bucket, across the aisle, and below the shafts-and-rods-and-tubes-and-pipes storage rack. Evidently the occasional drip became a steady drip while we weren’t watching; not a catastrophic flood, but far more water than we want on the floor.
This is the inlet valve, which is basically a flapper. You can’t see the fine cracks around the central mount, but they’re all over the inner half of the ring.

And this is the outlet valve, which has pretty much disintegrated. Note the outer rim peeled back under my thumb:

A complete new valve is $40, in stock and ready for pickup at Lowe’s, but all I really needed was the failed rubber flapper valves, which they don’t carry. A few minutes of searching reveals the Watts 0886011 Repair Kit, which has all of the interior parts.
Pop Quiz: How much does the repair kit cost?
Answer: Starts at $38 plus shipping and goes up from there. Cheap aftermarket kits run $20 and up, but they’re all out of stock.
Now that, party people, is the sort of thing that ticks me right off.
Perhaps the local HVAC / plumbing supply stores have such kits in stock? To quote: “They may exist, but we don’t have them.”
I don’t see any way to homebrew new flapper valves, so it’s off to Lowe’s we go…
It would seem to me that these things shouldn’t fail after a mere decade of service. I thought that about the CdS flame sensor that crapped out in the middle of a sub-zero January cold snap while I was at Cabin Fever some years ago, too.

