"Peggie Hall" wrote in message
t...
K2 wrote:
I am interested in installing a macerator pump for overboard discharge
(within legal limits). I understand the need for a vented loop (if not
installed where a thru hull can be closed when not in use). My current
"head installation" has a 1 1/2 " discharge hose routed through a
vented loop, then to a y-valve for direction to the thru hull or
holding tank. I would like to install a macerator pump from the
holding tank, but don't desire to dedicate the thru hull to macerator
discharge only. In other words, I would like to use the thru hull for
normal dischage (when within legal limits) without having to route all
waste to the holding tank first (and then to the macerator pump ). Is
it possible to direct the macerator pump output into a "T" , after the
toilet - before the vented loop?

It'll work if you move the existing vented loop to put it AFTER the
y-valve. You don't need a vented loop between the toilet and the tank,
only between the toilet--and now the macerator--and the thru-hull. Put the
loop as close to the thru-hull as possible and tee the line from the
macerator into the head discharge line as close as possible to the inboard
side of the loop.

You'd still need to keep the thru-hull closed except when the toilet is in
use--or while dumping the tank--though...to prevent sea water from being
forced up the line into the toilet or tank. A vented loop won't prevent
water from being PUSHED over it, it only breaks the flow of water being
pulled through it (a siphon)...and neither will a macerator. A macerator
will only slow it down quite a bit. If it's impractical to keep the
seacock closed except when using the toilet, put a shutoff valve in the
line that is accessible. And ALWAYS close both the intake and discharge
seacocks when leaving the boat no matter how big a PITA it is to to do it.
--
Peggie

Peggie
I'm involved in pretty much the same project as K2 and would appreciate
some clarification on a couple of your points.

You say "Put the loop as close to the thru-hull as possible ". Not sure
what you mean here. My vented loop is about 1 foot higher than the thru
hull. Wouldn't this lessen the chance of water being forced back into the
toilet?

You also say "tee the line from the macerator into the head discharge line
as close as possible to the
inboard side of the loop". This is the line from the y-valve to the vented
loop, correct? So when the Y-valve is set to run sewage to the holding tank
the toilet is shut off from the thru hull and you don't need to worry about
the macerator pumping back into the toilet, correct?

When the toilet is using the thru hull are you going to pump liquid into the
macerator discharge line and possible back into the tank? Could put a 1
inch ball valve in the macerator line.

Thanks