On Wed, 18 Oct 2006 20:10:40 +1000, Hinewai wrote:

His advice was not to bother with vented loops for the sink and
watermaker if we'd be there when those valves are open. In some ways
that makes sense (but.. zzzzz), but I was blown away when he said I
didn't need any vented loops at all with any of these pipeworks as
long as I double clipped all joints and put a vent on the lazerette
loop. He's seen the planned set up when he quoted me for the job, but
that seems like a crock of sh*t to me.

I'd welcome your thoughts (although still mean to put vented loops in
as planned). Any thought's on the brine side of the watermaker? I
must admit I can't see any need to vent the loop in the lazerette, but
maybe I'm totally confused over this whole issue.

I'm not as sure that what I'm doing is right as I was before I read
your message. I have vented loops where siphoning can either damage
something or will result in water flow into something that is open to
the interior of the boat. Vented loops are on the engine and genset
exhaust lines for the first reason. They are on the head feed and
pumpout lines and a washing machine drain for the second reason.

I didn't put them on the brine discharge line or the aircon and
refrigerator cooling water overboards because these are closed systems
that are used to having salt water in them.

There aren't any on the sink drains and I make a point of closing
those throuhhulls when under way. I guess there is some risk of
sinking at the dock if a drain line were to fall apart.

Incidentally, if your refrigerator vents above the waterline, be
careful about your watermaker pump sucking air through the
refrigerator's water line. My existing watermaker shares an inlet
through hull with an airconditioner and I have shutoff valves on each
line to reduce the possibility of sucking air. I still have some air
bubbles in the water maker water that I haven't found the source of.
That causes havoc to the membranes.

The new one is going to get its own throughhull. It's installation
manual says sharing a throughhull will void the warranty....for what
that's worth.