Hey Mike. What was the response regarding the use of (both) raw and fresh water inlet on a single head? Note your message on 3/3/2009 #768Thanks Peggy, I'll check with the dealer. While we have possession we haven't taken the official delivery on the boat yet so I'll add the toilets to my list of questions.
Toilets designed to use onboard fresh water need pressurized water...they don't work unless the fresh water pump is on to pressurize the system.
Yes, you can assume that the necessary siphon breaks and backflow preventers are installed in toilets designed to use pressurized flush water.
But as for whether toilets designed to use pressurized flush water can also be plumbed to use sea water, the answer is yes AND no. Some can, with the addition of a remote sea water intake pump, but not all. It requires a bit of rewiring and replumbing to make a toilet an "either or." Check with the mfr to find out if that's an option for your toilet. However, it might be less expensive to replace the toilets with ones designed to use pressurized flush water. If the boat is new, talk to your dealer to see if he'll swap 'em out for a lot less than just tossing and replacing.
Toilets that use pressurized flush water actually use about 20% less flush water than raw water toilets. So if you do swap 'em out, you'll use more of your fresh water, but your holding tank won't fill up quite as fast. And if you need to conserve your fresh water, a bucketful of sea water works.
It's definitely NOT possible to connect a toilet designed to use sea water to the onboard fresh water system...that cannot be done without damage to the toilet, contamination of the fresh water supply or both.
The accumulated suction only pulls bowl contents as far as the vacuum pump...the pump pushes it the rest of way while it simultaneously re-establishes vacuum in the system. So if you don't run the pump after urine only, it's not gonna get past the pump until you do run it. As for how long to run the pump...the vacuum switch has a built in gauge that automatically turns the pump off when the correct level of vacuum has been achieved...which, if the system is installed correctly, should also be about the same amount of time needed to push the flush from the pump to its destination (tank, thru-hull or treatment device).New to sailing but I changed out 4 older units in our 52 Defever for Vacuflush units. With a Vacuflush, you use so little fresh flush water that you holding tank can hold perhaps ten times as many flushes. Urine only requires enough water to cleanse the bowl, you don't even need to turn on the pump. If you go with a single toilet, they make a modular unit that cuts down on the plumbing. Put an on-of switch by the unit so that you do not need to run the pump 24/7. It will pump up in just a few seconds and you only need it for major jobs as long as gravity is with you.