Help - Head hose arrangement

Peggie Hall HeadMistress · Sep 9, 2018

You said you bought a new duckbill for the vented loop, but how often do you clean the entire air valve including the duckbill? Vented loops require a little maintenance, 'cuz the valve can't close if there's mineral or waste buildup in it.

And before someone suggests putting a vent line on the loop instead of an air valve....bad idea! Because the hose wouldn't be bigger than 1/4"...it would quickly become clogged by waste, salt, and minterals right at the loop, turn the loop into an UNvented loop that no longer has any ability to break a siphon.
And also, could the ventedloop be the source of infrequent smells? Even if working properly.
Nope.
So, eliminate the vented loop and plumb the hose directly to the thruhull?
Nope...maintain the loop instead.
And is there any problem with the macerator pump location?
Tanks with a discharge fitting IN the bottom of a tank that's entirely above the waterline are intended to be drained using just gravity, with a y-valve to provide a choice of pumping out or dumping. So I don't know why you'd need a macerator pump at all. You can also get rid of the y-valve in the head discharge line if you leave the tank discharge y-valve open to the thru-hull and also leave it open while in waters where you can legally flush directly overboard...flushes will just go through the tank and "out the door"....and you should do that because sludge on the bottom of the tank will slide into the line between the tank and a closed thru-hull, build up and block it.

I think we just seriously simplified your plumbing!

However, unless you're one of the very few people who's learned to use the "dry" mode to do more than move the last half cup of water out of the bowl, you have to have a never-ending problem with backflow from a toilet discharge line that runs 3' straight up. I dunno what we can do about that except learn to use the dry mode to move bowl contents ALL the way to the tank if you don't already know to do that...and it can. Any toilet that's working anywhere close to factory spec can move bowl contents up to 4 vertical feet in the dry mode...you said it's 3' to the tank inlet on your boat. Make sure to replace the joker valve at least annually 'cuz it's what supplies the necessary "ooomph" to do it.

--Peggie

Peggie Hall HeadMistress · Sep 11, 2018

Newport Bob said:
In reference to the vented loop. At one point you say keep it, but if I read correctly in another you suggest gravity dump of the tank - which I assume would not have the loop.I would like to remove it as it is up behind the sink where I can just reach with one hand.

I advised you to keep it before I realized your tank should be set up to drain via gravity. You're right...gravity dump tanks can't have a loop. They don't really need one because the entire tank is above the waterline. So feel free to remove it...it's location makes it pretty much useless anyway. Vented loops are supposed to be at least 6-8" above waterline AT MAX HEEL, not just when the boat is at rest...which on most sailboats puts it 2-3 feet above the bowl. I doubt if a loop inside the vanity is more than an inch or two above the waterline--if that high--even when the boat is at rest.

We're seriously simplifying your plumbing...but there's one thing we haven't discussed: the toilet's flush water intake plumbing. Unless you've rerouted the toilet intake line to tee into the head sink drain line, that's one place where a vented loop IS needed. It does NOT belong between the thru-hull and the pump 'cuz it'll interfere with the pump's ability to prime...it has be between the pump and the bowl, which requires replacing the short piece of hose the mfr used with two
pieces of hose long enough to put the loop where it belongs (photo shows both intake and discharge loops ). If that's how your toilet is plumbed, great...this info will be useful to others.

--Peggie

Rick486 · Sep 11, 2018

Newport Bob said:
HEAD HOSE ARRANGEMENT

Holding tank is mounted vertically on hull with bottom inline with top of toilet bowl and top of the tank about 3 ft higher.

Discharge from head goes to top of tank with y valve for direct discharge in the line.

Tank discharge hose is on bottom of tank and runs vertically about 4 ft to deck pumpout. There is an inverted Y fitting in this hose, about 1 ft above the tank bottom, with the other arm of the Y going down to the macerator pump mounted under the sink. The output from the pump goes vertical to a vented loop that is about 1 1/2 ft above the tank bottom and then down to a thruhull valve. All this of course under and on the hull behind the sink where I can barely reach.

PROBLEM

Checking the bilge the other day I found some smelly brown water. Checked the bottom of holding tank -dry hoses. Found wet at bilge area under the sink. Traced it up to fluid coming out the vent on the vented loop. Opened the thruhull valve - air rushed in - closed valve, leaking stopped. And of course had holding tank pumped.

QUESTION

Purchased a new duckbill for the vented loop, but before replacing it I have started thinking about this plumbing arrangement.

Why do I need the vented loop if the thruhull valve is only opened when the macerator is running?

And even if the thruhull valve remained open wouldn’t it only cause seawater to enter the holding tank to water level? I see no way for it to get water to the toilet bowl or cause any other sinking problem.

And also, could the vented loop be the source of infrequent smells? Even if working properly.

So, eliminate the vented loop and plumb the hose directly to the thruhull?

And is there any problem with the macerator pump location?

AND of course any other suggestions would be welcome.

THANKS FOR ALL RESPONSES

Hi Bob:
If I understand this correctly, since the bottom of the tank is at the same elevation of the top of the bowl, that would seem to tell me that the bottom of the tank is at or above the waterline, since the top of the bowl is by design usually at or above the water line. Since the macerator Y is a foot above the bottom of the tank I don't see how the tank could possible back siphon through the macerator discharge. Hence why would a siphon breaker be needed in the macerator discharge? The risk would seem to be exactly what happened. Discharge of sanitary through the relief valve.

Also, as you described the pressure relief drawing air when the sea cock was opened would possibly indicate the discharge line was pressurized, perhaps by accidentally cycling the macerator with the thru hull and Y valve both closed?
Also on our boat we only have the macerator thru hull open when pumping overboard (where allowed of course). Opened for the evolution, closed immediately afterward. No pressure relief in the line.
Rick

Gunni · Sep 11, 2018

Lose the y-fitting and install a y-valve. Keep the overboard hose closed and empty until you need to use it.

Peggie Hall HeadMistress · Sep 11, 2018

I think the tank may already have a second discharge fitting for the pumpout hose. If I'm right, I'd go with a simple PVC shutoff valve instead, 'cuz nothing would be attached to one of the outgoing hose barbs on a y-valve....and turning the handle to the wrong direction by accident is the last you'd want to happen.
--Peggie

Gunni · Sep 11, 2018

This is a fairly common Beneteau install: A y-valve in the head discharge hose allows the user to select discharge to the tank or direct overboard. The tank itself bottom discharges, in this case someone has added a y-fitting to that hose as it rises to the deck pumpout and plumbed it to a macerator pump which discharges to the thru-hull. The problem is this second overboard discharge hose is sitting full of waste (and has a vent in it as well). This second rarely used overboard discharge needs to be valved off (y-valve, replacing the y-fitting). Not only will this keep the hose clear of standing waste it will keep the macerator clear of standing waste.