Holding tank to manual pump to waste deck fitting

[summercamp]

I am getting ready to replace the holding tank system on a new purchase. Current set up has a Y-valve separating overboard discharge and tank. From the tank the discharge hose goes first to a manual diaphragm pump and then to a wast deck fitting.

Is this type of arrangement still used and are there any merits to having a pump that empties the tank to a waste deck fitting?

Thanks

[cal40john]

I haven't seen that before.

I did option 2 in the link below, and did the version in the note of having a tee instead of a Y valve. What they forgot to show was a pump in the line leading overboard. There's no Y valve before the holding tank. Everything goes into the holding tank, then you can either use a pumpout or pump the tank overboard.

http://www.dem.ri.gov/programs/benvi...s/podesign.pdf

West Marine also shows this, but doesn't show the option of using a tee instead of a Y valve.

The West Advisor: Heads Holding Tanks

[belizesailor]

Originally Posted by summercamp

I am getting ready to replace the holding tank system on a new purchase. Current set up has a Y-valve separating overboard discharge and tank. From the tank the discharge hose goes first to a manual diaphragm pump and then to a wast deck fitting.

Is this type of arrangement still used and are there any merits to having a pump that empties the tank to a waste deck fitting?

Thanks

A Y-valve is quite common, and I've seen plenty of manual pumps in place for overboard discharge, but never one that pumped up to the deck plate. You sure about that? Normally a pump out station has a strong vacuum pump that draws the waste up through the deck plate so there is no need for a pump in this side of the plumbing.

For over board discharge a very good arrangement, and one that is being used on many new builds, is a gravity dump. To do this the tank is installed above the water line and to empty it you just open a discharge valve. Less complicated plumbing and no pumps to maintain. Certainly an option to consider in your replacement install.

A very clean and simple gravity dump installation is just to plumb head direct to tank and tank to discharge valve. When inland/near coastal discharge valve is closed. When offshore valve is opened. Nice simple set-up and simple is good -- I've seen some real plumbing nightmares on waste systems.

[summercamp]

"I've seen plenty of manual pumps in place for overboard discharge, but never one that pumped up to the deck plate. You sure about that? Normally a pump out station has a strong vacuum pump that draws the waste up through the deck plate so there is no need for a pump in this side of the plumbing."

The set up is as I described. I don't have plans to stick with this arrangement but was curious about why it was set up this way. All of it seems original. The boat is an '85 and maybe set up for a time when there weren't vacuum pumpout stations?? Just a guess.

Thanks

[belizesailor]

Originally Posted by summercamp

...
The set up is as I described. I don't have plans to stick with this arrangement but was curious about why it was set up this way. All of it seems original. The boat is an '85 and maybe set up for a time when there weren't vacuum pumpout stations?? Just a guess.

Thanks

Don't know. Vaccum pumpout stations have been around for a long time -- definitely around in 1985. Maybe something unique to the owner's situation at the time?

Regardless, certainly not needed on the deck plate side normally. Maybe on a discharge line to pump overboard depending upon how you decide to set-it up.

Whatever you do though, don't install an impeller style macerator pump -- nothing but trouble.