"Set Square" wrote in message
...
In an earlier contribution to this discussion,
IMM wrote:


Not totally sure - but it could possibly be a double check valve
designed to be put in a cold water supply to outside taps etc., to
stop any dirty water from syphoning back into the mains if the mains
supply fails.

My God, and this one is telling me how pumps work. I despair. It is
a HepVo trap. Go to the hepworthplumbing web site. I can't be
bothered educating fools.

Then it's a good job that some of us have greater generosity of spirit! I
did admit that I wasn't sure about that one, never having seen anything
quite like it.

Despite your attitude, I have spent a considerable amount of time this
evening trying to educate *you*

On what? Not heating water and associated controls me boy. Never in a
million years. You are deluded.