vent routing

[kevindr]

My valiant 37 has the holding tank on the port side, under the V berth. The current vent is way too long and undersized. Assuming that the new vent has to go on the bow as its a sailboat, the horizontal forward distance is about 6 ' under the v berth. I then would have to raise it approximately 2' once in the chain locker. This would preclude it from being visible. Any thoughts on the diameter and routing ?

Also,

All wastage goes in the holding tank, then can either be discharged below the waterline via a pump, or sucked from the deck. The present configuration does not have a y valve. The hose from the tank and from the deck are t d into the pump. This was done as space is very very tight. Is this ok. I would think that sucking thru the deck like this could mess up the duck bills in the pump.

Thank You

 

[Peggie Hall HeadMistress]

Re your vent line... You're on the right track, but I need to know one thing: Where is the vent fitting on the tank? If it's not on the bow end, we may need to move it--which isn't hard to do, btw. I'd go with 1" ID.

Re your pumpout arrangement: there's no way that a pumpout can mess up the duckbills in the tank discharge pump unless the tank vent is blocked...'cuz unless it is blocked, the pumpout suction will pull in all the air it needs through the vent.

However, because duckbills need to replaced periodically as maintenance, I'd figure out how to put a y-valve in the system if I were you, 'cuz without one you have no way to close off the flow of waste from the tank to the pump to service it.

 

[kevindr1]

the vent is in the middle of the tank.
The tank is below the level of the pump, therefore I can change the duck bills without any trouble. I guess then that the y valve is not necessary.
so, your thoughts on the routing please ?

 

[Peggie Hall HeadMistress]

If you mean that it's in the middle of the TOP of the tank, your vent routing sounds fine.

 

[kevindr1]

Peggie,

Thank you very much for your assistance. My wife thanks you as well as she has been on my for awhile to straighten this out. I have attached a diagram of the current configuration, relative heights of the components are pretty close. Can you take a look and see if it makes sense. I am also wondering if the vented loop in the discharge line is necessary, as to siphon, it would need to go thru the pump, and tank. I have a Groco head therefore I cannot put a vented loop in the water intake loop.

Thank you again

 

[Peggie Hall HeadMistress]

It appears from your drawing that it's an uphill run all the way from the toilet to the tank. So I would keep a loop--though not necessarily a vented loop--in the head discharge line...it should be immediately after the toilet, slightly higher than the top of the tank. This will allow you to conserve flush water because you'll only have to pump long enough to push the bowl contents over the top of the loop....gravity can get it the rest of the way to the tank. If you replace the joker valve annually (do a search for "joker valve 101" to learn the REAL reason), you'll be able to use the dry mode to push it over, using flush water only rinse behind the flush.

If your Groco is a HF, you CAN put the loop between the pump and bowl, and you do need it. If it's an EB or a K, it doesn't need one because the intake is a valve that's separate from the pump.

Put a y-valve in the tank discharge line instead of a tee.

 

[kevindr1]

Thank you again. Can I ask why the Y valve ? I can service the pump without a problem as it is above the tank.