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Topic: Fresh water vent line (Read 969 times) previous topic - next topic

Fresh water vent line

Why is the vent line so large. I want to extend my vent line to the bottom of the coach and I was thinking of making the new
line a lot smaller. I would think 1/2 inch would be big enough as the hose used for filling is only half inch. I have the air bag out
so it is easier to get at.
Peter and Frieda Morin
1999 36ft. U320 Foretravel
Build # 5436
1998 Suzuki Sidekick Sport

Re: Fresh water vent line

Reply #1 –
I would not make smaller.  If overfilled, could bust your fresh water tank.
97 U295 40, Build #5040, 6C8.3 325 HP
Oregon Continuous Traveler
Samsung Residential #RF20HFENBSR,
Xantrex SW2012, (3)AGM8D Hse, (2)AGM Grp24 Eng, Victron BMV-712, 1800w Solar 4 LG & 2 Sunpower
Extreme Full Body Pt w/hdlmps, new furn/floor, 4 down Lexus 2004 GX470 AWD curb weight 4,740 lbs
Prev: 1990 Barth, 10L 300 2 yrs; 91&92 Monaco Signature, 10 yrs, 10L C 300 &  6C8.3 300; 1997 ForeT 6C8.3 325 since May 2017.  Employed by Guaranty RV 14+ yrs.  Former VW New Car Dlr/Service Dlr, Sales Mgr, Rv Sales, and Service Adviser from 1968-2017
"Don't criticize what you can't understand" Bob Dylan

Re: Fresh water vent line

Reply #2 –
I replaced my fresh water tank vent with a 3/8 plastic hose which terminates inside the upper cupboard in the bathroom.
I was not comfortable with how easy it would be for creepy crawlers to enter the fresh water tank.
I replaced the original white/blue hose with a clear hose of the same size (circa 1.5 inch) which terminates beside the gray water tank with a "T" and a crew on cap on the straight through. The ninety degree "T" faces up and has an adapter to attach the 3/8 plastic pipe to. There a pictures and more details in other post on Foreforums. I have never had an issue because I remove the cap when refilling the water tank.
Wyatt
96 U320 40 WTFE, build 4943
84 Toyota Supra towd
2015 Jeep Wrangler towd
Victoria, BC, Canada

Re: Fresh water vent line

Reply #3 –
Quote from: oldguy –
Why is the vent line so large.

Likely sized for the air that needs to vent when filling the fresh tank -and- to allow air into the tank when pumping it out when using tank water.  If made smaller, it would create pressure that would slow or prohibit filling of the fresh tank OR cause issues using the water from the tank.

I would not decrease the ID of the hose.
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320

Re: Fresh water vent line

Reply #4 –
Well I took it down to 1 inch from 11/4 so I will fill the tank tomorrow and see how it goes.
Peter and Frieda Morin
1999 36ft. U320 Foretravel
Build # 5436
1998 Suzuki Sidekick Sport

Re: Fresh water vent line

Reply #5 –
Not to totally disagree with Michelle-- vent size is directly proportional to the fill size and volume .  If you are filling with a 5/8 garden hose at 50PSI then 1/2" vent would be sufficient.  If you are filling with a 1-1/2 in line at 50 PSI 1/2 inch would not be large enough
Just sayin
Chris
1999 U 320 DGFE
Build Number 5523
Chris & Elka Lang
In the field, Lonoke AR

Re: Fresh water vent line

Reply #6 –
I'll let you know I reduced mine to 1/2 Im going to run another piece down below rear bulkhead.I sm about at the point to refill water tank and will report back.
Also remember you are filling the tank through a 1/2  pex anyway.  Unless you have some kind of direct fill . I don't so I think this will work fine.
91 GV U300 Unihome 40' Build 3811
6V92TA Detroit

Re: Fresh water vent line

Reply #7 –
As long as you don't leave shore water on after the tank has filled you may be OK.  The over-sized vent is to prevent the tank from exploding from more water entering than can escape.

So you have taken it from "idiot proof" to "owner must always pay attention".  YOU will have to judge if this is the right answer for YOU.  How about subsequent owners???
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Fresh water vent line

Reply #8 –
Nice pictures Stump. The elbow was cut off on the bulk head fitting on my coach so mine was harder to do.
Peter and Frieda Morin
1999 36ft. U320 Foretravel
Build # 5436
1998 Suzuki Sidekick Sport

Re: Fresh water vent line

Reply #9 –
Quote from: wolfe10 –
As long as you don't leave shore water on after the tank has filled you may be OK.  The over-sized vent is to prevent the tank from exploding from more water entering than can escape.

So you have taken it from "idiot proof" to "owner must always pay attention".  YOU will have to judge if this is the right answer for YOU.  How about subsequent owners???
Maybe I'll tell them...
Well the owner should be paying attention. If your not going to Pay Attention you probably have No Business owning a Vintage Motorcoach.
My Coach is 28 years old now.I'm not real concerned about the next guy..If they are Crazy and Determined enought too take on owning a Vintage Coach they will figure it out soon enough..Plus they might be able to possibly search this forum and find this thread..
91 GV U300 Unihome 40' Build 3811
6V92TA Detroit

Re: Fresh water vent line

Reply #10 –
Quote from: oldguy –
Nice pictures Stump. The elbow was cut off on the bulk head fitting on my coach so mine was harder to do.
I silicone that nipple in the original fitting. Then slightly bent the metal diffuser out some so it would go back in. If it dosent work Its easy to take back out.
91 GV U300 Unihome 40' Build 3811
6V92TA Detroit

Re: Fresh water vent line

Reply #11 –
I had an elbow the same size as the original line and I'm going to keep it the same size as it was as I'm going to urethane spray over it.
I don't want to have to change anything. Thanks for all the advice.
Peter and Frieda Morin
1999 36ft. U320 Foretravel
Build # 5436
1998 Suzuki Sidekick Sport

Re: Fresh water vent line

Reply #12 –
Quote from: oldguy –
I had an elbow the same size as the original line and I'm going to keep it the same size as it was as I'm going to urethane spray over it.
I don't want to have to change anything. Thanks for all the advice.

Are you extending the overflow down past the airbag? Picture?
97 U295 40, Build #5040, 6C8.3 325 HP
Oregon Continuous Traveler
Samsung Residential #RF20HFENBSR,
Xantrex SW2012, (3)AGM8D Hse, (2)AGM Grp24 Eng, Victron BMV-712, 1800w Solar 4 LG & 2 Sunpower
Extreme Full Body Pt w/hdlmps, new furn/floor, 4 down Lexus 2004 GX470 AWD curb weight 4,740 lbs
Prev: 1990 Barth, 10L 300 2 yrs; 91&92 Monaco Signature, 10 yrs, 10L C 300 &  6C8.3 300; 1997 ForeT 6C8.3 325 since May 2017.  Employed by Guaranty RV 14+ yrs.  Former VW New Car Dlr/Service Dlr, Sales Mgr, Rv Sales, and Service Adviser from 1968-2017
"Don't criticize what you can't understand" Bob Dylan

Re: Fresh water vent line

Reply #13 –
I'm extending it so it is below the coach and pictures is something I will have to learn about.
Peter and Frieda Morin
1999 36ft. U320 Foretravel
Build # 5436
1998 Suzuki Sidekick Sport

Re: Fresh water vent line

Reply #14 –
Well Jack I'm trying to see if I can download a picture
Peter and Frieda Morin
1999 36ft. U320 Foretravel
Build # 5436
1998 Suzuki Sidekick Sport

Re: Fresh water vent line

Reply #15 –
Looks like I succeeded.
Peter and Frieda Morin
1999 36ft. U320 Foretravel
Build # 5436
1998 Suzuki Sidekick Sport