Pumping out

[RonD]

PeggieI happened to be down below at the head while they pumped out my holding tank the other day. The through-hull was closed, and the Jabsco toilet valve in the dry-bowl position.I noticed that when it got down to the dregs, the pump started sucking the remaining stuff out of the toilet, then air. Is that normal, or is it an indication that my vent line might be blocked? I'm generally on-deck during this operation so I wouldn't have noticed the phenomenon before.--RonD

 

[Peggie Hall/HeadMistress]

Gotta be the vent

It would be one thing if the toilet discharge hose entered the tank at the bottom, but it comes into it at the top...so for the pumpout to need air through that hose, it can't be getting enough through the vent...it's trying to pull in enough air to keep up with the amount of waste or air that's being sucked out from anywhere it can get it.The problem is in Catalina's approach to holding tank venting: running the vent line into a rail stanchion that has only a tiny little slit in it. Not only does that just about guarantee odor out that slit every time the head is flushed, but the slit isn't big enough to allow enough air through it to keep up with the pumpout. Other builders don't do any better...they use stainless "caps" that only have about the same size slit in the bottom. The cure: either a bigger hole in the stanchion or get it out of there and run it to a thru-hull--an open bulkhead fitting that lets enoug air in AND out.

 

[RonD]

Second & third question

PeggieThanks.1. Will the sucking of air through the bowl, etc. damage anything (e.g., the joker valve)?2. I don't think the C320 vents through a stanchion -- there appears to be a small vent cap on the topsides just above the stripe under the rubrail and aligned with the deck waste plug. I saw a recent post that claimed the cap can be unscrewed for cleaning & blowing out the vent -- is that so?--RonD

 

[Peggie Hall/HeadMistress]

It's not good for the toilet...

It's especially not good for the tank or the plumbing...'cuz the toilet doesn't let much air through. A particularly strong pumpout can collapse the head discharge hose, or worse yet, implode the tank. A vent thru-hull "cap" that can be unscrewed is a new one to me...I've never seen or even heard of any till now. Since that type of vent thru-hull is "universal"--designed primarily for use on fuel tanks (including gas) and including a spark arrestor, but boat builders use 'em on holding and water tank vents too because "standard" vent sizes are the same 5/8" on all tanks--it wouldn't make sense that the cap could be removed...'cuz it would be too easy to lose it. That would not only cancel any spark protection on a fuel tank, but any protection from water intrusion when the boat is heeled. Otoh, I'm often amazed by the amount of after-market stuff available that doesn't make sense...so I guess it is possible.