head sea cocks

[H3newdog]

Hey James, I meant to ask if it was okay to connect the two vents to one thruhull, not to just loop them. I found out when I had to pump out twice about making sure the vent was clear. I understand the reason for the vented loop and what I call an air admittance valve to break the siphon or what I call backflow. I have seen several plumbing diagrams which I base mine on. Mine should be close if not the same as I see and read kloudie1 (see above)

 

[H3newdog]

Anyway I've been summed to speak with the Headmistress so I'm sure she will point out my flaws and explain why. I believe this would be the first time I have ever looked forward to having to "see" a headmistress.

 

[JamesG161]

I meant to ask if it was okay to connect the two vents to one thruhull, not to just loop them.

Yes if the size of your thru hull is sized for both and is not restricted to prevent proper IN combined flows. However, it would be rare to have both the head and macerator working a same time.

You second diagram of "closed loop" I would NOT do.

Your first diagram is roughly the same as my Hunter , like kloudie1.

My siphon break is to prevent hold tank back flow to head and is behind the head cabinet also. BTW you would have to have an almost full Hold tank to back flow since the Hold Tank vent acts also as a siphon breaker.

air admittance valve to break the siphon or what I call backflow

is good description.

My maceration pump is about 5 gpm that is about the flow of a 5/8th inch garden hose. Resistance to air flow in a pipe , is much much less that black water. It is up to you but a 1" line is a bit excessive. The vent, for sure, would be less size than your pump discharge diameter. You should keep that air vent line short and sweet ( no kinks ).

Valves are a restrictive piping part and if used in your black water line, should be full port ball valves. I wouldn't put one there. Partial closure is a "trap for crap" pun intended. That line should be for easy long sweep 90° degree turns for easy of cleaning.

This is science and not a guess. Air vent lines are common in house hold sewer and sink drains.

BTW I would never hook fresh water to Black water. Sink drains are grey water. I have a glass next to each head to finally pour fresh water to prevent briny smells when leaving the boat.

I am an chemical engineer and would be glad to help on sizing if you email me.
Jim...

 

[kloudie1]

Newdog, your post 37 is exactly what came from Hunter originally. I have a "y" valve that was in a box, uninstalled, when I bought the boat (in 1991) and it is still there in the box because the scheme seems to work fine for me. The seacock can stay closed unless offshore.. No valves to manipulate to make it work..
You do not need to vent the top of the vented loop to the outside because there is a check valve in there that keeps foul smells inside the line.. and allows air to go to the inside only, to keep seawater from siphoning .. although the check valves in the diaphragm pump would do that mostly too.
Attached is the plumbing diagrams from the original owners manual for the 34. Not easy to see, but it shows your post 37 for the head.

 

[kloudie1]

Wouldn't put in an electric pump since they are kinda notorious about freezing up from little use and leaking from corrosion.. The diaphragm pump doesn't mind sitting still.. a caution is that if you have any salt scale in the holding tank, the scale can flake off in chunks like fingernails which can foul the "joker" type check valves in the pump.. It pays to rinse, disassemble, and clean out the scale from the valves when you hear it in the diaphragm..

 

[H3newdog]

I'm a little confused, it appears to me that JamesG161 and kloudie1 both claim my diagrams are what they recommend only James references the first diagram and Claude refers to post 37 which is the new plan.
I fully comprehend the venting, air valve & understand the anti siphon loop. My plan for the vent on the top of the loop to be connected to the tank vent was in the event of it sticking open it would not vent into the cabin. Peggy says that adding this line could be problematic if it clogs. No disagreement from me there. When I pulled the high loop out it had a lot of "dirt" that I thought might have emanated from a stuck vent.
What I don't see is the need for the vented high loop between the toilet and the tank. I think it is only needed between the tank and the seacock. I'm looking forward to my time with the Headmistress later today to sort this out and understand the why's and why not's.

 

[JamesG161]

What I don't see is the need for the vented high loop between the toilet and the tank.

You need the high point loop!!!

Or Hold tank can run backwards to head. The bottom of the high loop hose MUST be higher than the boat water line by a few inches.

The siphon break on high point is NOT needed as long as the head fills your hold tank from the top, tank is NOT full and the hold tank is vent is NOT blocked (notice all 3 things MUST be true. In essence the hold tank vent would break the siphon with perhaps the volume of the Head-Hold tank line flowing backwards for a bit.

The siphon break just prevents siphoning the hold tank to head and over flows in cabin.

My recommendation is put the high point siphon break and maintain it once a year.

If it was just grey soapy water, no big deal
But...
Otherwise .... not much fun on a cruise to clean up head back flow.

My boat is similar to kloudie1 diagram in post #44, except I have a macerator pump. Notice item #14 in his diagram is "vented loop". Hunter has years of design experience!

From my Engineer view... It works fine.

Here is worst case...

Seacock on pump to sea is open and pump fails (that happened to me but we rapidly closed the seacock, whew). Water fill the hold tank then will back flow thru the head and flood your boat if you high point is NOT above boat water line.

It may be confusing, but there are several things going on.

The real solution to put a head on the deck with shower curtain. Just kidding.
Jim...

PS: I did comment on your diagram #2 showing connecting the siphon break to vent in a closed loop. That won't work.

 

[kloudie1]

Newdog.. The Hunter diagram shows the vented high loop in the line between the manual tank pump (discharge) and the thru-hull, which prevents seawater back-flow into the holding tank when heeled over to starboard.. The little vent valve is easily removed and washed.. about every other year is OK. No tools required on mine, it is hand tight. No other loop is absolutely necessary because the top of the toilet bowl is a smidge above the waterline.. Pretty sure Peggy will tell ya to put another vented loop into the small line between the head pump and the bowl so that if the head valve leaks, seawater cannot fill the bowl and overflow onto the shower sump.. If two people are in the vee birth, the loop is necessary. I know this. The bow-down trim will be enough to have seawater overfill the bowl; this will get your attention when (at 2 AM) you exit the vee and step in water! The lady in the vee had forgotten to switch to "DRY" position on the Jabsco pump. The pictures in my "Test Post" show the piping involved in the original Hunter set up.. Has worked perfectly for me over past 24 years.. As James says, the head discharge must go into the top of the tank; there should be an "air break" between the inlet to the tank and the liquid.. No dip tube on the black water inlet. The vent of the tank should slope up to that outlet on the hull side; no dips in the line to hold liquid. You can use a dock water hose to flush the vent from the outside each time you pump out as soon as liquid is being sucked out of the tank to the pump-out.

 

[H3newdog]

That's good info kloudie1, until now I didn't have a good inside "water line level". I have seen the light about using the loop(s) with the air valve. I think I'll add the loop from the pump to the bowel as no way am I ever going to try to explain to a woman that her presence in the v-bert caused my 12000lb boat to loose trim. No Way!

 

[H3newdog]

Don't know James curtain on deck sounds like a good way to discourage unwanted boat guests.

 

[JamesG161]

Well, the deck head is a direct drop!

My boat galley sink is direct drop to a thru hull under the boat. Direct drop or not the boat water level is the level water in the sink drain. I simply put a stick in the drain and see how many inches to the counter top water level is.:dance:

Then I can reference the counter top to anywhere on the boat. I have hidden marker tape in all heads and storage showing AWL.

The Hunter (Builders Information Plate ) has a loaded boat weight that determines the stated draft. You can see the static LWL in the specs too. We use depth of keel on tankers to determine cargo weight. You can do the same. Measure the length of your wetted hull (rough length is ok ) and compare to loaded LWL. The ratio of that length to spec will tell you % cargo load. I have only done that at party times. Lottsa beer lottsa food lottsa people.

We all know that rough seas move water levels. My exhaust seal loop has that problem when using auxiliary power in heavy seas. I can hear the difference in noise on an up bow wave.

When you design you system take all of the above into account.

My offer still stands, if you need any engineering design or confirmation, email me. BTW, remember free advice is worth what you paid for it.

Hoping all your troubles are FLUSHED away....
Jim...

 

[H3newdog]

Thanks for the info and offer Jim. None of my sinks drains are anywhere close to straight but alas they need to be repaired and the old plastic replaced anyway. Prior to haul I noticed the boat sitting way up which I figured appropriate due to it being mostly empty. I'll have to remember the % of load calculation method. Several others have mentioned that they don't like the exhaust location due to it's potential to be underwater.

 

[Genkigary]

I got rid of the holding tank, Raritan head and all the related tubing and replaced with an Air Head composing head. No more odors. No more pump outs. Bliss!!

 

[Peggie Hall HeadMistress]

Uh- huh...and how are you enjoying toting those gallon jugs full of urine ashore? Or are you just pouring 'em overboard like everyone else who's ignoring the fact that doing that is just as illegal as dumping a tank?:naughty: