Originally Posted by phorvati
So what do boats with two head usually do? Two holding tanks?
Builders, most of which are the worst sanitation system designers/plumbers on the planet, often install just one tank in an effort to save money
. That wouldn't be quite so bad if they put the tank halfway between both toilet...but they almost always put the tank reasonably close to one of the toilets, and UNreasonably far from the other one. Owners are stuck with finding a solution.
A second tank within about 6' of the aft toilet is the right solution. Ronco Plastics Ronco Plastics marine Tanks
makes TOP quality thick-walled water and waste tanks for a very reasonable price
and has more than 400 shapes and sizes, over 100 of which are non-rectangular (which means you might be able to fit a larger one in the same space), and they install fittings in the sizes and locations specified by the customer when they make the tank.
Eder wrote: I have vacuflush heads...one of them is about 25' from black tank. Works flawlessly and uses about a liter of fresh water or less per flush.
The distance from the bowl to the tank is irrelevent. It's the distance from the vacuum pump to the tank that matters 'cuz the accumulated "vacuum" pulls the bowl contents TO the pump..the pump then has to push it the rest of the way to the tank while it's also sucking the air out of the line between the toilet and the pump...and I think you'll find that the tank isn't that far from the vacuum pump.
I've written a piece I call "VacuFlush 101" that explains in detail how it works. I'll be glad to send it to you if you'd like to send me a PM that includes your email address (no way to attach anything to a PM).
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein