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wunderluster · 06-05-2012, 11:30

I am replacing a broken hose between the seacock and the vent loop. I noticed the valve on top of the loop is totally clogged. Can I just unclog it or is it a one way valve that needs to be replace?

David

**SkiprJohn** · 06-05-2012, 11:50

It's usually a one way valve but it doesn't hurt to keep it open as long as it has a hose to it that goes high above the waterline and is vented outside.
Others may chime in on this and they might be more expert than I.
kind regards,

**Ocean Girl** · 06-05-2012, 13:47

VentedBoat Marine Plumbing Vented Loop Thru Hull loop

I'm on an iPad so can't play the tech tips but the forespar site should talk about maintenance of the the one way valve of the vented loop. Though the CSY I think have the metal vented loops..? Yes? No matter the principle is the same.
If I remember correctly the one way valves have a little rubber duckbill shape dohicky inside, they are notoriously easy to clog

. So to answer your question, the loop isn't a one way valve, but it has a one way valve on top which allows air to escape, avoiding a suction situation.
Hope that helps, happy sanitation project

Erika

peghall · 06-05-2012, 14:12

That valve is an "air valve"...it's purpose is to break a siphon by allowing air INTO a line through which liquid is being pulled, but doesn't let air or anything out...so it IS necessary that it be working. Try to clean it...if you can't, contact the mfr for a replacement air valve...they don't cost much.

You've also provided a good illustration of the reason that I do NOT recommend putting a "vent line" on a vented loop instead of installing an air valve. People put vent lines on 'em because air valves are sold separately for the most common vented loops--PVC with a nipple on the top that has a hole in it...most people don't even know air valves exist. The loop squirts liquid or waste if no air valve is installed...so they put a hose on it. But the hose is so small--only 1/4" ID--that sea water minerals and/or waste clog it almost immediately, turning the loop into an UNvented loop that no longer has any ability to break a siphon. Because it's solved the squirting problem it's now "out of sight, out of mind...never cleaned or even checked.

Otoh, a lot of people don't know that air valves need regular cleaning and occasional replacement either....

**GordMay** · 07-05-2012, 05:44

What Peggie said.
For more, see Jabsco’s information sheet ➥ http://www.xylemflowcontrol.com/files/itemdoc1391.pdf

S/V Alchemy · 07-05-2012, 08:28

Quote:

Originally Posted by SkiprJohn

It's usually a one way valve but it doesn't hurt to keep it open as long as it has a hose to it that goes high above the waterline and is vented outside.
Others may chime in on this and they might be more expert than I.
kind regards,

No, that's the generally accepted route.

The idea of an anti-siphon loop with a hose leading up and out (perhaps to a deck or coach-house fitted gooseneck of the plumbing type) is generally foolproof, whereas valves and piston-style siphon breaks can fail, clog or otherwise not perform.

I have had issues with such loops in my exhaust systems and am going the "1/4 inch hose to a deck fitting" route because I'm tired of kerosene flushes.

The same will hold for the head. KISS rules.

peghall · 07-05-2012, 12:55

Read my previous post to this thread to learn why a 1/4" hose on a vented loop is a BAD idea.

How hard can it be to rinse out an air valve once a month and replace it once a year???

Johnny Henry · 08-05-2012, 18:30

I have a 1989 Albin 40 trawler that has several vented loops. The loops are 1 inch metal tubing with a 1/4 inch valve on top. I need to know where I can get replacement valves or just the joker part.
Thanks

peghall · 08-05-2012, 21:09

Got any idea of the brand name for the vented loop? If they aren't all the same, can you post photos?

**HopCar** · 08-05-2012, 21:26

Scot Pump Co. makes a loop vent that is pretty clog resistant. It is avalible in several thread configurations and can be made to fit most loops. http://www.scotpumpmarine.com/Group_...2011-03-03.pdf
If you can't find them locally give me a call, I've got them in stock.
Buy Peggy's book. I've got that in stock as well.

**GordMay** · 09-05-2012, 05:33

Greetings and welcome aboard the CF, Johnny Henry.

S/V Alchemy · 09-05-2012, 06:27

OK, if Peggie doesn't like it (for the head, at least), perhaps I can reconsider.

I think it's still OK for exhaust loops, however, because it's just hot water, not biologicals.

peghall · 09-05-2012, 07:07

It's not about "biologicals," it's about buildup that clogs the line...and sea water mineral buildup can occur in any line that carries sea water.

Johnny Henry · 11-05-2012, 08:51

Thanks for the info Guys, I have not found a manufactores name on the loop. I did take the valve apart. The working part of the valve consist of a small flat rubber disc about 1/4 inch diameter that has an off-centered hole about 1/16 inch diameter. When pressure from the loop increases the rubber part moves up to block the small hole in the cap, when pressure drops and suction starts the rubber drops allowing air to enter thru the small hole in the cap. I made a new rubber piece by cutting a doubled strip of electrical tape with a hole punch and then cutting a notch on the edge. It tested fine, how long it will last is now in question.

**Cheechako** · 11-05-2012, 09:09

If you have one of those common tiny vented loop valves with the little rubber piece in them, they are ridiculous. I would bet that most people running around thinking they have a vented loop in their head hose really just a have a big elbow! Someone used to make a floating ball type of vented loop replacement valve.... seems that would be much better. You can try extending the valve above the loop with a hose and fittings after you clean it out.