On Tue, 06 Nov 2012 07:19:28 -0800, rlz wrote:

I agree with the prior posts that the backflow preventer is necessary.

OK. I don't disagree. It's there for a reason.
I'm going to try to understand the thing and then repair it.

BTW, I can't tell if it's a 1" or a 1.5 inch opening
because it clearly has a "1" stamped on each opening
but it's just as clearly got a 1" pipe going in and out.

Here, for example, is a ruler next to the pipe and
a yellow circle around the 1.
LARGE: http://www3.picturepush.com/photo/a/...g/11346746.jpg
SMALL: http://www3.picturepush.com/photo/a/...0/11346746.jpg

Notice the pipe is actually about 1 3/8ths in diameter, so it's
neither 1 inch nor 1.5 inch.

Q: What size would you say this Wilkins Zurn 975XL actually fits?