Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 17-03-2011, 09:25   #16
Marine Service Provider
 
peghall's Avatar

Community Sponsor
Cruisers Forum Supporter

Join Date: Feb 2011
Posts: 1,533
Re: Holding tank vent

A screen actually creates more problems than it solves because it does get clogged very easily and also makes it all but impossible to backflush the vent line. If you have one, knock it out!

As for the size...5/8" ID has been the standard size for fuel and water tank vents for decades preceding the need for holding tanks...and because it works for fuel and water, the industry--not knowing squat about sewage management--just assumed that 5/8" was also the right size for waste tanks, especially since it lets builders use the same vent thru-hull (that's actually designed to prevent back flames from GAS/Petrol tanks) on all of 'em. So ya pretty much gotta change out the thru-hull, for an open bulkhead fitting, even if it's the same 5/8", to be able to maintain the vent by back flushing it.
__________________
2017 Peggie Hall
Specializing in marine sanitation since 1987
Author "The NEW Get Rid of Boat Odors"
https://www.amazon.com/New-Get-Rid-B...dp/1892399784/
peghall is offline   Reply With Quote
Old 17-03-2011, 09:30   #17
Moderator Emeritus
 
GordMay's Avatar

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 31,592
Images: 240
Re: Holding tank vent

Quote:
Originally Posted by capn_billl View Post
My sanitation guy stated that dried bits of TP often clog the vent at the waterline of the tank. The only way to fix this is to put pressurised water back down the vent line. He uses a garden hose connected to what looks like a plunger head stuck up against the thru hull to wash these vent lines.
Quote:
Originally Posted by peghall View Post
... Vents should be backflushed--which cannot be done if a filter is in the line--every time the boat is washed and/or the tank is pumped out.
Indeed.
__________________

__________________
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 17-03-2011, 10:15   #18
Registered User

Join Date: Jan 2009
Location: Maple Bay BC
Boat: Cal 2-29
Posts: 31
Images: 1
Re: Holding tank vent

Quote:
Originally Posted by capn_billl View Post
My sanitation guy stated that dried bits of TP often clog the vent at the waterline of the tank. The only way to fix this is to put pressurised water back down the vent line. He uses a garden hose connected to what looks like a plunger head stuck up against the thru hull to wash these vent lines.
Well I've heard it all now, so where is the pressure created supposed to be relieved while doing this? as the deck suction should be going to the bottom of the tank below the liquid level.
__________________
nylajo is offline   Reply With Quote
Old 17-03-2011, 10:26   #19
Senior Cruiser
 
Sailmonkey's Avatar

Cruisers Forum Supporter

Join Date: Sep 2009
Location: Houston
Boat: '76 Allied Seawind II, 32'
Posts: 5,787
Re: Holding tank vent

Quote:
Originally Posted by nylajo View Post
Well I've heard it all now, so where is the pressure created supposed to be relieved while doing this? as the deck suction should be going to the bottom of the tank below the liquid level.

This isnt' uncommon at all, when I pump out the tank I hold a hose over the vent line for a while so that water is sucked in instead of air.
__________________
Sailmonkey is offline   Reply With Quote
Old 17-03-2011, 10:29   #20
Marine Service Provider
 
peghall's Avatar

Community Sponsor
Cruisers Forum Supporter

Join Date: Feb 2011
Posts: 1,533
Re: Holding tank vent

Very little pressure is created by putting just a couple of gallons of water under pressure down the vent line...and what little IS created is relieved as soon as you remove the device. Ordinarily the plunger head wouldn't actually be used as a plunger, but only to cover the thru-hull so that all the water goes down the vent...although I guess it could be used to pull a plug out of the vent that doesn't want to be washed into the tank by back flushing the line. IMO, it's a bit of overkill for any owner, though...at least, it is if you don't ignore the vent till it does get so firmly plugged up that you have to call a pro with a plunger to unclog it.
__________________
2017 Peggie Hall
Specializing in marine sanitation since 1987
Author "The NEW Get Rid of Boat Odors"
https://www.amazon.com/New-Get-Rid-B...dp/1892399784/
peghall is offline   Reply With Quote
Old 17-03-2011, 12:18   #21
Registered User

Join Date: Dec 2009
Posts: 181
Re: Holding tank vent

You are correct Peggie, the hose is indeed 5/8" ID. Brain fade. As with the Sealand check valve description. Again brain fade. I replaced the vent hose and thru hull last winter with new, the thru hull does indeed have screens. In fact, the outter part of the fitting has 2 smaller holes that are only approx 1/4" dia. each. Between those 2 small holes and the screen, this is no doubt the majority of the venting restriction. Thinking possibly this vent is more designed for fuel tank venting, than holding tank?


Thanks for all the replies. Shows me some flaws that will need to be changed.
__________________
US1Fountain is offline   Reply With Quote
Old 17-03-2011, 13:48   #22
Marine Service Provider
 
peghall's Avatar

Community Sponsor
Cruisers Forum Supporter

Join Date: Feb 2011
Posts: 1,533
Re: Holding tank vent

If you check the marine catalogs you'll see that ALL "vent" thru-hulls are designed for use on fuel tanks...the industry just uses the same thru-hull for all tanks 'cuz it's cheaper and doesn't require the guy who's installing 'em to think about which one should go on which tank.

Btw...if your vent line isn't straight, that should be fixed too. Ideally it should be no longer than 3' (anything up to 5' will be ok, but not great)...straight as an arrow, and no sags in which water or waste can pool. It shouldn't rise more than 45 degrees either...but while that's not too difficult on a powerboat, it can be impossible on a lot of sailboats.
__________________
2017 Peggie Hall
Specializing in marine sanitation since 1987
Author "The NEW Get Rid of Boat Odors"
https://www.amazon.com/New-Get-Rid-B...dp/1892399784/
peghall is offline   Reply With Quote
Old 17-03-2011, 18:44   #23
Senior Cruiser
 
Therapy's Avatar

Cruisers Forum Supporter

Join Date: Jul 2007
Location: W Florida
Boat: The Jon boat still, plus a 2007 SeaCat.
Posts: 6,894
Images: 4
Re: Holding tank vent

What diameter vent line would be proper for an 18 gal holding tank?
__________________
Therapy is offline   Reply With Quote
Old 17-03-2011, 19:02   #24
Registered User

Join Date: Dec 2010
Boat: Beneteau/343
Posts: 182
Re: Holding tank vent

Quote:
Originally Posted by Mark Johnson View Post
This is a good point! My wife flushed the head into a 100% full tank once, and it goes right up the vent hoses and down the hull! I used a homemade fitting & garden hose to blast a strong stream of water in the maze fittings, (from the outside), and down the vent hoses. This clears the clog nicely.

Mark
Is there a way to monitor the status of the tank? ie to know how full it is?
__________________
davefromoregon is offline   Reply With Quote
Old 17-03-2011, 19:49   #25
Registered User

Join Date: Dec 2009
Posts: 181
Re: Holding tank vent

Quote:
Originally Posted by peghall View Post

Btw...if your vent line isn't straight, that should be fixed too. Ideally it should be no longer than 3' (anything up to 5' will be ok, but not great)...straight as an arrow, and no sags in which water or waste can pool. It shouldn't rise more than 45 degrees either...but while that's not too difficult on a powerboat, it can be impossible on a lot of sailboats.

My thru hull is approx 1-1 1/2' directly above the tank, which is located along the hull side, so to eliminate the filter, the vent hose will go straight up and curve at the thru hull. This would prevent the less than 45 degree angle recommendation.
__________________
US1Fountain is offline   Reply With Quote
Old 17-03-2011, 19:52   #26
Registered User

Join Date: Dec 2009
Posts: 181
Re: Holding tank vent

Quote:
Originally Posted by davefromoregon View Post
Is there a way to monitor the status of the tank? ie to know how full it is?

Both my holding and fresh water tanks have the Tank Watch level indicators. They are indicator lights that indicate empty, 1/2, and full.
__________________
US1Fountain is offline   Reply With Quote
Old 17-03-2011, 21:11   #27
Registered User
 
Coachbolt61's Avatar

Join Date: Jan 2011
Location: Newcastle Australia
Boat: Bollard Steel 40ft - Lady Kara
Posts: 137
Images: 17
So Peg, where can we go to get up to date information from you?
Smiles
Coachbolt.
__________________
Coachbolt61 is offline   Reply With Quote
Old 17-03-2011, 21:18   #28
Registered User
 
Coachbolt61's Avatar

Join Date: Jan 2011
Location: Newcastle Australia
Boat: Bollard Steel 40ft - Lady Kara
Posts: 137
Images: 17
Quote:
Originally Posted by US1Fountain

Both my holding and fresh water tanks have the Tank Watch level indicators. They are indicator lights that indicate empty, 1/2, and full.
I would have thought better levels would have been empty, 3/4 (look for a pump out) and 7/8 (too late! Get a bucket).
Smiles
Coachbolt.
__________________
Coachbolt61 is offline   Reply With Quote
Old 17-03-2011, 21:18   #29
Marine Service Provider
 
peghall's Avatar

Community Sponsor
Cruisers Forum Supporter

Join Date: Feb 2011
Posts: 1,533
Re: Holding tank vent

Quote:
Originally Posted by davefromoregon View Post
Is there a way to monitor the status of the tank? ie to know how full it is?
There definitely is! Practical Sailor rated the Scad Monitors a couple of years ago: Tank Monitors | Technologies LLC I love these gauges. The beauty of 'em is that the senders are on the outside of the tank, so they can never become clogged by the animal fats in waste as float switch senders do. And, they're affordable. You can get a single tank monitor or one that can handle up to 8 tanks--waste, water and fuel.

Btw, CG regs require that all tanks have a means of determining when they're at least 3/4 full. If access to the tank provides visual inspection, no gauge is needed...otherwise, your'e supposed to have one. However, that's buried so deep in the regs that many CG inspectors don't even know about it.
__________________
2017 Peggie Hall
Specializing in marine sanitation since 1987
Author "The NEW Get Rid of Boat Odors"
https://www.amazon.com/New-Get-Rid-B...dp/1892399784/
peghall is offline   Reply With Quote
Old 17-03-2011, 21:20   #30
Marine Service Provider
 
peghall's Avatar

Community Sponsor
Cruisers Forum Supporter

Join Date: Feb 2011
Posts: 1,533
Re: Holding tank vent

Quote:
Originally Posted by davefromoregon View Post
Is there a way to monitor the status of the tank? ie to know how full it is?
There definitely is! Practical Sailor rated the Scad Monitors a couple of years ago: Tank Monitors | Technologies LLC I love these gauges. The beauty of 'em is that the senders are on the outside of the tank, so they can never become clogged by the animal fats in waste as float switch senders do. And, they're affordable. You can get a single tank monitor or one that can handle up to 8 tanks--waste, water and fuel. You can read all about 'em at the link I've provided.

Btw, CG regs require that all tanks have a means of determining when they're at least 3/4 full. If access to the tank provides visual inspection, no gauge is needed...otherwise, your'e supposed to have one. However, that's buried so deep in the regs that many CG inspectors don't even know about it.
__________________
2017 Peggie Hall
Specializing in marine sanitation since 1987
Author "The NEW Get Rid of Boat Odors"
https://www.amazon.com/New-Get-Rid-B...dp/1892399784/
peghall is offline   Reply With Quote
Reply

Tags
holding tank

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
Clogged Holding Tank Vent Hose Gabrielle37 Plumbing Systems and Fixtures 11 07-06-2014 12:05
For Sale: Holding Tank Vent-Line Filter roberttigar Classifieds Archive 0 05-08-2010 11:20
How to Clear Blocked Holding Tank Vent ? Cruisin Home Plumbing Systems and Fixtures 25 15-07-2010 09:15
Need to cut a hole in my boat (holding tank vent) rebel heart Construction, Maintenance & Refit 9 14-10-2007 20:48



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 02:10.


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.