On Sun, 06 Jan 2008 07:00:17 -0800, Clive wrote:

After reading this newsgroup and the very clear Readers Digest book
on plumbing, I braved replacing the flap valve in my sister's toilet.

Point of information: that is *not* a flap valve. What you're describing is
the diaphragm in a syphonic cistern valve. A flap valve is a modern (to
the UK, since water regs changed a few years ago) type with a flap of
plastic covering the cistern's flushing outlet pipe or orifice. Pulling
the flap up (by a linkage to the handle or button) lets water out of the
cistern rapidly to flush the pan. A float built into the flap keeps it up
once it's been pulled up until all the water has gone out, whereupon it
falls back down and seals the outlet. There's a rubber washer sealing the
flap to the outlet.

--
John Stumbles