Check Valve on Inlet Line?

[edwardc]

Peggy,

I'm in the process of installing a brand new PH Superflush, and I am planning on putting a tee in the seawater inlet line so a single thru-hull can feed both the toilet and the anchor washdown pump. Will I need to put a check valve in the line leading to the PH Superflush in order to prevent the washdown pump from sucking air backwards through the head's pump, or is its internal valve robust enough to perform this function?

If a check valve is needed, is the Raritan RCV a suitable choice? I'm leery of putting a plastic fitting below the waterline.

 

[Peggie Hall HeadMistress]

You'd need a vented loop in the head intake anyway (see installation instructions for the right location), but I have a better idea: reroute the head intake line to tee into the head sink drain line just above the seacock. That'll free up the head intake thru-hull for your washdown pump AND provide a safe way to supply fresh water to the toilet to rinse the sea water out of the whole system before the boat will sit.

 

[Gunni]

I'm in the process of installing a brand new PH Superflush, and I am planning on putting a tee in the seawater inlet line so a single thru-hull can feed both the toilet and the anchor washdown pump. Will I need to put a check valve in the line leading to the PH Superflush in order to prevent the washdown pump from sucking air backwards through the head's pump

That is exactly how I have my systems set up. Works great. You do not want or need a check valve because when you winterize the boat you shut off your thru-hull, pull the hose off the easily accessed Superflush pump drop a funnel in it, turn on your washdown pump and let it suck up and discharge the AF through your washdown system - done!

 

[NYSail]

You'd need a vented loop in the head intake anyway (see installation instructions for the right location), but I have a better idea: reroute the head intake line to tee into the head sink drain line just above the seacock. That'll free up the head intake thru-hull for your washdown pump AND provide a safe way to supply fresh water to the toilet to rinse the sea water out of the whole system before the boat will sit.

Peggie,
That is a good use of holes, but wouldn't you pull sink debris like soap, toothpaste etc.... that has been put in sink and ultimately floats in the pipe into the toilet when you flush. Could this be detrimental to the unit internals or is it robust enough to digest stuff from though intake?

Greg

 

[Peggie Hall HeadMistress]

but wouldn't you pull sink debris like soap, toothpaste etc.... that has been put in sink and ultimately floats in the pipe into the toilet when you flush.

No, because you wouldn't flush "used" sink water, you'd fill the sink with clean water (this would require cleaning the sink first if it's as disgusting as your question makes it seem to be...surely it's not!)

Tee the intake line into the head sink drain line below the waterline, as close to the seacock as possible. This will allow you to flush using sea water as you're doing now. But now you have a safe way to use fresh water to rinse all the sea water out of the whole system--intake line, pump, channel in the rim of the bowl AND the discharge line (just putting clean water in the bowl and flushing it only rinses out the discharge line). When you're closing up the boat to leave it, AFTER you've closed all the seacocks (you DO close the seacocks???), fill the sink with CLEAN water...flush the toilet. Because the seacock is closed, the toilet will pull the water out of the sink, rinsing out the whole system. No more odor from seawater left to stagnate in the toilet pump and plumbing.

Btw, this is described in detail on page 52 in my latest book, available from sbo.com online store (see link in my signature)

 

[trevor1955]

Peggie,

My head sink drain and toilet intake are tee-d at a single seacock/thruhull below the waterline as you describe on Page 52 of your book. With the seacock closed the drain supplies fresh water to the toilet; this works very well.

If/when I do decide to use seawater for flushing the the toilet I must obviously open the seacock and suck in seawater with the toilet pump. However, as my head sink is just about at the waterline (Catalina 27) the drain hose from the sink will fill with seawater to the level of the water line; is that correct? If so, I would then need to flush out the seawater with fresh water to avoid the smell of the seawater in the hose.

What I am thinking is to install a P-trap on the sink drain to prevent the seawater smell from leaving the hose. What is your opinion on this idea?

Trevor

 

[Peggie Hall HeadMistress]

All you really need to do is pump enough times to get rid of all the sea water after you close the drain seacock but before you pull the plug in the sink.

The real benefit to teeing the toilet intake into the sink is, you can flush with sea water instead of using valuable fresh water until you're preparing the boat to sit...at which time you flush all the sea water out of the system, preventing the sea water odor problems. If you add a cupful of distilled white vinegar to the sink water each time, you also prevent sea water mineral buildup in the system.

 

[trevor1955]

I am trying to minize the usage of freshwater, and minimize what gets pumped into the holding tank.

 

[Peggie Hall HeadMistress]

So how would flushing with sea water all the time except when using a sinkful--about 2 liters--of fresh water to rinse out the system increase your use of fresh water compared to flushing with fresh water all the time? UNLESS you're flushing with gray water ("used" sink water), which is a really BAD idea because all the soap scum etc in gray will really foul up a toilet pump.

As for minimizing what goes into the holding tank...the same amount will go in no matter where the flush water comes from.

What am I missing here?

 

[Richard19068]

As for minimizing what goes into the holding tank...the same amount will go in no matter where the flush water comes from.

What am I missing here?

In my experience if the seawater valve is open a lot more water will be used to flush the toilet and end up in the tank as compared to actually watching how much fresh water is being sent down the sink or directly into the bowl. It is harder for people to visualize how much seawater is being pumped through the system.

 

[Ron20324]

I am trying to minize the usage of freshwater, and minimize what gets pumped into the holding tank.

Take some gallon jugs of water to be used strictly for that final fresh flush.

 

[Peggie Hall HeadMistress]

Read "Manual toilet flushing 101" on page 33 in my book to learn how to use the "dry" mode to conserve flush water..