Re: Weird problem with Sill***

In article <5OFKe.4043$Je.658@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>, cweinke@xxxxxxxxxxxxxxxxx (Charlie) writes:

| I just had this happen to me last night on my outdoor faucet. It's a
| 'frost-free' style that has the stem washer back in the wall about 12". When
| I open the valve it doesn't leak from the packing nut, but from a small
| hole in the stem itself (???), which is visible when you remove the
| handle...

I have one like this as well. The discharge through the inside of the
stem appears to be intentional. At the inside end of the stem is a piston
mechanism with a spring that pushes it into the position that opens the path
to the stem and blocks the water inlet. (Closing the valve also blocks
the inlet and the stem path by compressing the spring.) As long as there is
enough pressure at the inlet to drive the piston against the spring and into
the stem the stem path is sealed. I'm not sure why the mechanism is built
this way. Perhaps they now want the reverse-check function to be referenced
to atmospheric pressure plus whatever the spring adds? Or perhaps they want
a discharge path for reverse flow so it won't have a chance to work its way
through the check valve into the water supply? Does this have anything to
do with the reduced pressure zone protector valves for sprinklers that
the plumbers now say are better than the old double-check valves? (The
latter do not have a discharge but the former do.)

Note that the above-described mechanism is in addition to the anti-siphon
(vacuum breaker) device on the outside end of the fixture. Also, it is
not an "in-use" drain for the frost-free function since it will not drain
the fixture while the valve is off. The "in-use" drain is yet another
spring-loaded piston on the bottom of some frost-free fixtures that opens
on low pressure regardless of the state of the main valve.

Anyway, it appears that the piston can get stuck so that it does not fully
seal the discharge path out through the stem. Usually fully closing the
valve correctly repositions the piston, but I'm afraid the little fingers
on which it slides can get bent or simply become rough with scale. Since
the piston mechanism does not appear to relate to the forst-free function,
perhaps the original poster has one in his normal sill***.

Dan Lanciani
ddl@danlan.*com
.

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