Basic Waste Plumbing Setup - How many y-valves ?

[ChannelIslander]

Hello,

Am I right in thinking that the head should pump to a y-valve that can direct flow to either an overboard seacock or to the holding tank, and that the holding tank should drain to a second y-valve that directs flow to either the macerator pump or to the pump-out hose?

Thanks,

Nick

[Vyndance]

Yes you are! Add an anti siphon to both overboards.

[rebel heart]

More basic, if you have the design for it, is to have the waste go to a holding tank that's higher than the head. Vented, it functions as the antisiphon. Run a Y out of holding tank to overboard and the deck.

[HopCar]

You don't need the second Y Valve. A simple pipe tee on the tank outlet will work. One leg of the tee goes to the deck fitting, another leg goes to the macerator or better still diaphram pump. I suggest you read Peggy Hall's book before you get too far into this.

[ChannelIslander]

HopCar,

I have a system already and am trying to diagnose why it's not working.

Last time out I tried the macerator after having fixed the wiring and turned the shaft manually to break up the locked pump. The macerator ran, at least the pump motor did, but did not actually pump anything out.

I kind of suspected a shot impeller, but what did happen was that an awful, strong odor arose. No sewage leaked, and after a while I thought that perhaps there _should_ be a second wye valve, and that the system was trying to pump up the pump-out hose.

Is it correct to think that a broken impeller is likely the cause of the running pump not actually pumping?

And what would cause an emission of stinkiness if the macerator runs with a busted impeller?

Thanks so much

N.

[captain465]

Did you check the rotation of the pump? If it was reversed, you would not pump anything out, and you would pump up into the holding tank and disturb the contents.

[Watercolor]

ChandlerIsland,

If I may, a couple questions to ask yourself. How long have you owned it, have you rebuilt your system or replaced any hoses, etc. recently, If the head system hasn't been used for a while you might have some nasty anaerobic bacteria. As HopCar suggested a look at Peggie Hall book on head systems.

What I'm wondering is if you have any liming in the line from the tank to the seacock or the seacock is closed and the handle isn't working. You could be pushing waste into a brick wall and the result is coming out off a leaky vent or vented loop, or very possibly up the deck pump-out line Is there any standing waste in the lines? Can you define exactly where the smells coming from? On some of the newer Catalina 36's the holding tank is on the starboard side aft and high and can cause some real problems.

I also think Captain 465 may be right and you should check the impeller. I feel that you'll find that a new impeller (a) doesn't really care as far as the blades are concerned, or (b) the metal fitting will dictate the direction it has to go. If you're putting in the old impeller I don't know what happens if the impeller is put in reverse from the way it was taken out, my guess it will destroy the impeller.

Head systems are great fun, I know from personnel experience, when thinking about digging into my head system I used to go into a cold sweat. The key for me was to open my mind to all options, even the ones you dread, then calmly work through the components, the simplest first. Head systems are fairly simple, it's the chemistry and physics that can be tricky.

As an aside, I would respectfully disagree with Rebel Heart's idea of placing the holding tank above the head. I know it's done, but here are my observations.

1. You have standing waste from the head to the tank. So smells can be a big issue. Hoses with standing waste will smell very quickly. I'd try and avoid standing waste or at least design it so that that section of hose can easily be replaced.
2. Beside the basic hose fittings the only thing between the head bowl and the waste is the joker valve. If you've got 3 feet of hose to the tank or the boat is healed, guess where it can go even with a vented loop. That newer Catalina I mentioned, on a starboard tack all the hose waste backed up directly on the joker valve. And the valve just gave up. Not a pretty sight.
3. There's one boat mfg who uses a tank where the output hose uses a standard threaded fitting to hold the hose in place. The only thing holding the hose tight was the Oring and the collar. The collar vibrated loose. Again not a pretty sight.

I'm not trying to be negative. I just wanted to give people a heads-up on the issues. If you have such a system, just be aware of the issues and watch for possible problems.

One of the problems with boats is that everything has to fit within the hull. Sadly, boat manufacturers seem to consider head systems an unwanted stepchild.

On a boat there's no easy answer. Murphy's law is on steroids and Murphy loves it when people say "I've always done it this was, never had a problem doing it this way."

[Vyndance]

Originally Posted by HopCar

You don't need the second Y Valve. A simple pipe tee on the tank outlet will work. One leg of the tee goes to the deck fitting, another leg goes to the macerator or better still diaphram pump. I suggest you read Peggy Hall's book before you get too far into this.

You may want to reread the book. I would hate to repair the pump with just a simple tee between the pump and tank.

[HopCar]

Good point Vyndance. I don't have one on my boat but the pump is mounted pretty high and it hasn't been an issue. I can see it would be a problem if the pump was mounted lower.

[peghall]

As long as you've already taken my name in vain...here's how I'd set up the system...

If spec'ing out a new system, I'd put one y-valve between the toilet and the tank...but instead of another y-valve, I'd put TWO discharge ports in the tank--one directly to the deck pumpout, the other directly to the overboard discharge pump, vented loop and thru-hull. Ideally, I'd want ALL the fittings to be on the top of the tank, with pick up tubes inside the tank on the discharge fittings....however, that requires at least 5" clearance above the tank, which isn't always possible...in which case, a shut-off valve AT THE TANK on the line to the discharge pump.

However, we're dealing with a system that's already in place...

You said, "Last time out I tried the macerator after having fixed the wiring and turned the shaft manually to break up the locked pump. The macerator ran, at least the pump motor did, but did not actually pump anything out."

Can only be one of two things: 1. a failed macerator impeller or...2. a blocked tank vent that causing the macerator pump to to pull a vacuum that prevents it from pulling anything out. My money is on #2, but if you've run the macerator very long, by now you prob'ly have both problems.

A clog in the tank discharge is a third possibility, but that's unlikely.

"And what would cause an emission of stinkiness...?"

The odor from a tank that's become pressurized due to a blocked tank vent has to go somewhere, most likely in the direction in which it's being pulled by the macerator.

The two most common locations for a tank vent blockage are the vent thru-hull and vent line connection to the tank--both the tank fitting and that end of the vent line. So first thing to do is grab a screwdriver or whatever works to scrape out the vent thru-hull...and I'd try to stay to one side--preferably the UPwind side of it--and have a hose handy, 'cuz the spew can be impressive if this relieves the pressure. Whether it does or not, next loosen the deck pumpout fitting to relieve any pressure remaining (again, try to stay out of the way!)...now it's safe to remove the vent line from the tank to scrape out the fitting and that end of the line.

Do not use the toilet again or attempt to pumpout or dump the tank until you're sure the vent line line clear. If the macerator still runs without moving anything through it, replace the impeller.

And if you want to modify your system to make it easier to maintain, it's not that hard to do...send me an email.

[ChannelIslander]

Peggie,

The vent is not clogged, I do not believe, for when I pump out I can feel air being sucked down the vent (it's in a stanchion) into the tank. I can block the vent hole with my finger and then release it and a whoosh of air is sucked in.

The macerator itself has a date of 1998 on it.

My money's on the impeller at this point. I'm thinking of replacing the pump.

However, there is no overboard discharge for the head on my boat. There is a thru-hull but it is capped. So I guess I will have to install a wye-valve and seacock and hose on that end.

Regarding the macerator discharge having an anti-siphon valve. Mine is mounted about six inches above the hull, with a very short hose connecting to the thru-hull. I only would open the thru-hull valve when I was going to operate the macerator . . . why would I need the anti-siphon valve, which would result in a length of hose between the macerator and the anti-siphon that would sit with waste in it, and with the anti-siphon valve to act as a vent. Or am I missing something?

thanks so much for your response.

- nick

[peghall]

I[d agree that it's prob'ly time to replace a 13 yr old macerator pump. Consider going with an electric diaphragm pump (SeaLand T-Series pump is the best choice) this time instead. There's a current thread about this right here.

ABYC standards call for vented loops in all lines connected to below-waterline thru-hulls, but whether you choose to do that is up to you. You can get away without one if you mount the macerator above tank.

Anti-siphon devices do not act as vents...at least they're not supposed to. There should be an air valve installed in a vented loop--a one-way valve that only allows air INTO a line through which liquid is being pulled (a siphon)...nothing out. Air valves are replaceable parts that need periodic cleaning and occasional replacement. NEVER put a vent LINE on a vented loop! The line would only be 1/4" ID--so small that salt, sea water minerals, waste will clog it almost immediately, turning the vented loop into an UNvented loop that no longer has any ability to break a siphon. Because it's solved a problem--squirting--it becomes "out of sight, out of mind"...totally ignored from then on.

Do yourself a HUGE favor: relocate the tank vent from the stanchion to a proper thru-hull. You'll get a lot better air flow, and less odor, in your tank if you do. Catalina is about the only mfr who puts 'em in rail stanchions, but even they have finally begun connecting waste tank vent lines to thru-hulls. And go with a 1" ...not a "vent" thru-hull, but a plain ol' bulkhead fitting. If you're worried about taking on water through it, put a clamshell over it.

[rebel heart]

Originally Posted by Jedg

As an aside, I would respectfully disagree with Rebel Heart's idea of placing the holding tank above the head. I know it's done, but here are my observations.

No worries in disagreement on that topic. The guy asked for a "basic" setup, which is why I went with the one that has the least amount of moving parts and connection points that's legal in countries requiring holding tanks. The gravity method is far from ideal, but as you said "ideal" can be pretty hard to find on an onboard head.