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Monday, January 12, 2009

Forward Head Plumbing

Ok, I have heard a couple rumors over the past month that, with the economy the way it is, Dometic/Sealand, makers of VacuFlush, might be running a BIG promotion come this spring. And, it will be a manufacturer program that will not undercut dealers and distributors (contact your local dealer!). So, in hopes of taking advantage of the promotion, if it happens, I have started the hack design of the heads. Starting with the forward head, the picture shows the major components involved. I was hoping that one of their prepackaged HTS systems would fit, but that is not to be the case. The goal of the forward head design to such that there is not evidence of "complex" head machinery. That means a flush back splash panel behind the head behind which everything is wired and plumbed. None of the HTS systems will fit. The thing I like about the VacuFlush system is the "Tank Manager" component. Which is a keyed lock operated discharge system that can operate in fully automatic, manual, or "shut down" mode. In full auto mode, the system senses when the holding tank gets full and initiates the overboard discharge pump (IF the discharge sea cock is open for which there is a electric lockout switch). "Manual" initiates overboard discharge whether or not the tank is full (again if the sea cock is open). "Shut Down" mode turns off discharge altogether. The Tank Manager, as it requires a key, satisfies the US Coast Guard requirement for securing overboard discharge equipment in no-discharge zones when the system is in "shut down" mode (that is, if the only key is in possession of the captain). Next steps in the design:
  • design such that a Raritan Electro-Scan can be fitted AFTER the fact. This device essentially turns your head system into a "Sewage Treatment Plant" making it legal to discharge effluent over board. I say "after the fact" because I am undecided on this piece of equipment. Seems owners either LOVE or HATE it (due to breakdowns and/or maintenance). This device would make overboard discharge legal NOW, but if laws change...
  • rig a manual hand operated overboard discharge pump. Sticking with only an electric pump virtually ensures it will fail at the most inconvenient time. Don't ask how I know...
  • there will be a shower sump under the floor in the forward head. Plumb it such that the pump can be pumped into the holding tank, or direct overboard.
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