Vented loop

[Cambo]

Hi guys,


I bought my boat last season and I am slowly fixing it up.

The boat had a newer head in it hooked up to the old plumbing but the holding talk was removed at some point.

I have installed a new holding tank and I am going to replace the sewage lines and vent too.

The old lines have a vented loop in them, which from my understanding is because the head is below the waterline.

My question is, should I be replacing the vented loop or should it be cleaned out so it can vent? I'm assuming the vent has to be straight up.

Any info or tips would be great!

 

[Stu Jackson]

Which old lineS had loops in them? Usually it's the 1 1/2" to the holding tasnk and the 3/4" btween the pump and the bowl.

Any head installation manual, easy to find online, will show you.

 

[Joe]

 

[sailorhokie]

We sail coastal in the Chesapeake Bay. Obviously our direct discharge is always closed but we also use fresh water from a jug to keep the yuck of bay water out of the holding tank to reduce smell and keep the raw water intake closed.

I am assuming one only needs vented loops on heads if the through hulls are intended/regularly used underway?

Josh

 

[Cambo]

Thanks guys,

The vent is currently on the sewage line to the tank but I don't think there was one on the water intake to the toilet, ill have to take a look today.

 

[Bill Roosa]

Unless the level of the holding tank at any time is above the level of the toilet when empty you don't need a vented loop on the hose. Anytime you connect to a thru-hull and the other end of the hose is below the waterline you need a vented loop.

 

[Stu Jackson]

Thanks guys,

The vent is currently on the sewage line to the tank but I don't think there was one on the water intake to the toilet, ill have to take a look today.

Not the line from the thru hull to the pump, but between the pump and the bowl.

The WM Advisors are also helpful:

http://www.westmarine.com/WestAdvisor/Selecting-a-Sanitation-System

 

[thinwater]

... I am assuming one only needs vented loops on heads if the through hulls are intended/regularly used underway?

Josh

Obviously, with no through-hulls open there is no need. However, this is a sink-the-boat item if it goes the wrong way. I think you will find that insurance surveys are rigid (rightfully) on this. Just do it.

 

[Joe]

The essence is this, if the toilet bowl is below the water line when the boat is heeling, then there is a chance of accidental syphoning.... so the insurance policy is to surround the bowl with anti syphon vented loops. These are not stopper valves, flapper valves, joker valves etc. which can fail if not serviced regularly. A vented loop has small air check filament that can be easily inspected, adjusted or replaced.

So, the conceptual diagram from the Jabsco installation guide, shown in post #3, shows the vented loops on the supply and discharge sides of the bowl. That's it... all the other items... holding tank, manual overboard pump, Y-valves, etc. are outside the vented loop barrier that protects the bowl from allowing water into the boat.