Holding tank vent fitting options

[HeadedToTexas]

The hot air gun sounds way safer than a torch. Fingers are crossed.

 

[HeadMistress]

My holding tank capacity is reportedly 30 gallons. The vent line has always been in the top of the tank as I understand most are. As the contents of reach 30 gallons, the vent line becomes an overflow line, true? The deeper the Uniseal tube protrudes through the seal into the tank, the lower the usable capacity of the tank gets and the higher my chances get to someday accidentally pump some poop into the bay. Are there not ABYC safeguards against that? I know the Y valve must be locked out, but the vent line seems far more likely to allow a spill than a less than familiar guest finding and opening that Y valve. Anyway, hence my obsession with the Uniseal fitting.

The tank vent line should never be allowed to become an overflow...one of the reasons USCG regs require means of determining when the level of the tank contents reaches 3/4 full. If the tank is in a location and made of a material that makes visual inspection possible, that is acceptable. If not, a tank level indicator is required.

There is no need for the pvc pipe to extend more than 1/2" below the Uniseal.

--Peggie

 

[HeadedToTexas]

I get that, and I get that raw sewage in most places is a serious problem. Thinking more about it, my system would overflow out of the heads before it would leave via the vent line. Bad news in any case.

 

[Comodave]

I get that, and I get that raw sewage in most places is a serious problem. Thinking more about it, my system would overflow out of the heads before it would leave via the vent line. Bad news in any case.

I think that Peggie is more concerned about the sewage drying up in the vent hose and plugging it up. With most vent hoses being a small diameter they can plug up pretty easily. You would not likely get much overflow out the vent and going overboard.

 

[HeadedToTexas]

Among the items on this winter's boat project list is installing this new 1" holding tank vent. I have the through hull fitting figured out and the UniSeal ready to install in the holding tank top, but my 1" hose will not fit through the ¾" gap between the top of the tank and the wood section forming the bottom of the forward bulkhead. How would you guys proceed?

 

[Bacchus]

My tank has vent at top of fwd end of the tank. It was small dia and tortuous path to stbdb side and usual fuel fill vent ftg w screen.
Ii rerouted from original position (top / fwd end of tank) straight fwd under fwd cabin berth to the bow area using larger hose and straight mushroom thru hull ftg.

 

[HeadedToTexas]

I am hoping to avoid fixing the old vent hole in the hull and making a new one, but that may be an option.

My next step is to determine the function of that wood strip that reduces the clearance to less than an inch. It might just be a trim strip in which case I can relieve enough space to get the 1" hose through unimpeded. Fingers are crossed.

 

[Bacchus]

I simply abandoned my old vent hose and a fuel fill thru hull but left them disconnected in place. I could not even access the hose connection in spite of an access plate near the fthru hull igs as MS connected them prior to assembling the hull to deck connection and all hose figs were inaccessible... at least w/o significant work.