Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 23-08-2015, 23:19   #1
Registered User

Join Date: Aug 2015
Posts: 2
Genset Vented Loop

Recently the generator vented loop has started discharging seawater through the syphon valve while it is running. The rubber valve is in good condition.
Does anyone have any suggestions as to what has changed and how to fix it?
It flows onto a run of wires which is also a concern.

Thanks in advance.

Len
Selene 43
__________________

__________________
Lenihe is offline   Reply With Quote
Old 24-08-2015, 03:22   #2
Moderator Emeritus
 
GordMay's Avatar

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 31,579
Images: 240
Re: Genset Vented Loop

Greetings and welcome aboard the CF, Len.
__________________

__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"



GordMay is offline   Reply With Quote
Old 24-08-2015, 05:13   #3
Moderator
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Albany Ga.
Boat: Island Packet 38
Posts: 17,045
Re: Genset Vented Loop

Pretty much can't be in good condition, it leaks now. I'd replace it.
__________________
a64pilot is offline   Reply With Quote
Old 24-08-2015, 07:36   #4
Senior Cruiser
 
Sailmonkey's Avatar

Cruisers Forum Supporter

Join Date: Sep 2009
Location: Houston
Boat: '76 Allied Seawind II, 32'
Posts: 5,773
Re: Genset Vented Loop

Depending on the manufacturer.....I'd guess the duckbill has gotten hard and gave up. Some you can by a replacement for, others you just replace the whole thing.


Sent from my iPhone using Cruisers Sailing Forum
__________________
Sailmonkey is offline   Reply With Quote
Old 24-08-2015, 10:45   #5
Senior Cruiser

Cruisers Forum Supporter

Join Date: Mar 2014
Location: Anacortes
Boat: previous - Whitby 42 new - Goldenwave 44
Posts: 1,735
Re: Genset Vented Loop

Some vented loops don't have a duckbill valve at all. They have piece of clear tubing that goes to the bilge. You can have it on a vent with a duckbill too. But it should not be spitting water out constantly. I am not sure what would cause that other than a blockage downstream or too much pressure/flow from upstream. Just seems odd in my experience.
__________________
exMaggieDrum is offline   Reply With Quote
Old 24-08-2015, 11:09   #6
Moderator
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Albany Ga.
Boat: Island Packet 38
Posts: 17,045
Re: Genset Vented Loop

Quote:
Originally Posted by exMaggieDrum View Post
Some vented loops don't have a duckbill valve at all. They have piece of clear tubing that goes to the bilge. You can have it on a vent with a duckbill too. But it should not be spitting water out constantly. I am not sure what would cause that other than a blockage downstream or too much pressure/flow from upstream. Just seems odd in my experience.
I've even seen some use clear aquarium tubing to have a "pee" tube similar to an outboard motor (remove the valve) I believe when I install the water separator on my generator I may do that, so I'm sure it's getting water flow, plus of course as this is just an open tube, nothing to stick or wear out too.
__________________
a64pilot is offline   Reply With Quote
Old 24-08-2015, 11:14   #7
Registered User

Join Date: May 2008
Posts: 1,967
Re: Genset Vented Loop

Feel around with a piece of stiff wire for any weed that might be keeping the rubber from seating.

What is the brand of valve? (a picture would be better)

If it's in a location that easy to replace, I'd just replace it. Also check the others on your boat. One that is stuck closed could sink your boat by allowing a siphon. It's really unlikely but why take the risk?....

I like the Forespar ones as they are Marelon so have no corrosion and spare duckbill rubber pieces are available (i carry a few spare duckbills).
__________________
CarlF is offline   Reply With Quote
Old 24-08-2015, 13:55   #8
Registered User
 
svHyLyte's Avatar

Join Date: Mar 2006
Location: Tampa Bay area, USA
Boat: Beneteau First 42
Posts: 3,432
Images: 25
Re: Genset Vented Loop

If you are getting back-flow through the vent on the "vented loop", it is likely you have an obstruction between the vent and the through hull that is preventing the free discharge of cooling water which "back's up" in the loop circuit. If the generator is not run often (most aren't), you could very easily have critters "growing" in the discharge line, not unlike the build-up of material in the arteries. One can check, to some extent, by freeing the discharge side of the loop from the vent and inserting a simple cone nozzle from a garden hose into the hose end. If the discharge hose is "clear", water from the garden hose should blow through quite easily, if not, it too will back flow into the boat around the cone. Should that happen, you might try closing the sea-cock at the thru-hull, draining as much water out of the discharge line as possible (if necessary using a 1/4" diameter tube inserted into the discharge line as far as possible and the suctioned out with your shop-vac, and then refilling the discharge hose with a solution of Barnacle Buster or RydLyme and water and allowing that to site over night. Either of those materials will dissolve any hard-shell critters and kill off any other growth. Then, open the sea-cock, and wait another day (the mixture will clear whatever may be growing on the ocean-side to the sea-cock). Finally, reinsert the cone end from your garden hose, and blow out the line with fresh water. If "growies" are the obstruction, the foregoing will clear them out pretty effectively and get you back in business. (BTDT--Got the T-Shirt)

FWIW...
__________________
"It is not so much for its beauty that the Sea makes a claim upon men's hearts, as for that subtle something, that quality of air, that emanation from the waves, that so wonderfully renews a weary spirit."
svHyLyte is offline   Reply With Quote
Old 24-08-2015, 16:47   #9
Registered User

Join Date: Aug 2015
Posts: 2
Re: Genset Vented Loop

I have several vented loops with the same duckbill set up. When I switch them the problem still persists.
The obstruction theory sounds the most likely at this point so will try that in the next couple of days.
Thanks for the suggestions.
__________________

__________________
Lenihe is offline   Reply With Quote
Reply

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Servicing Raw Water Vented Loop - Vetus MarkJ Engines and Propulsion Systems 7 27-06-2013 10:41
Plastic Anti-Siphon Valve for Vented Loop Dick Locke Plumbing Systems and Fixtures 4 17-07-2009 23:49
Vented Loop Question pressuredrop Plumbing Systems and Fixtures 16 22-06-2009 16:20
2" Vented Loop Source Stevens 47 Plumbing Systems and Fixtures 31 20-02-2009 08:45



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 02:04.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.