Water Tank Fill Issue...

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ButchW

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Apr 14, 2021
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97
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La Mirada, CA
I had this same problem with my old 5th wheel... When filling my new to me motorhomes fresh water tank, I 1st filled with a bleach mix to sterilize the tank.. Draind it, then refilled to flush the bleach mixture... No problems... But when I started filling the final time, the water would "burp" back out the fill tube.. The vent wasn't venting... This is the 1st time I have ever filled the tank, and had no problems while sanitizing.... No matter how slow I filled, it would burp back... I would think it would vent around the water in the fill tube if I filled at a slow rate... Could I somehow have kinked the fill tube?.. Would a plugged vent couse this?
Butch
 

NY_Dutch

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Nov 22, 2010
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Where our wheels take us!
The problem can occur when the filling water enters the vent tube and prevents air from escaping. A short length of hose that fits in the filler hose will reach past the vent and prevent the water from blocking it. You can make your own or Camco makes a one that works well.

 

Rene T

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May 20, 2011
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18,665
Location
Farmington NH
I had this same problem with my old 5th wheel... When filling my new to me motorhomes fresh water tank, I 1st filled with a bleach mix to sterilize the tank.. Draind it, then refilled to flush the bleach mixture... No problems... But when I started filling the final time, the water would "burp" back out the fill tube.. The vent wasn't venting... This is the 1st time I have ever filled the tank, and had no problems while sanitizing.... No matter how slow I filled, it would burp back... I would think it would vent around the water in the fill tube if I filled at a slow rate... Could I somehow have kinked the fill tube?.. Would a plugged vent couse this?
Butch
Just a side note where this is new to you, you should have run your onboard water pump and filled the entire water system including the water heater to get the entire system sanitized.

It’s common to have the tank burp while filling. Because of the size of the fill hose and the inside diameter of the fill tube, there’s not enough clearance to allow the air to bleed out. You need to use a smaller hose and fill slowly.
 

ButchW

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Joined
Apr 14, 2021
Posts
97
Location
La Mirada, CA
The problem can occur when the filling water enters the vent tube and prevents air from escaping. A short length of hose that fits in the filler hose will reach past the vent and prevent the water from blocking it. You can make your own or Camco makes a one that works well.

Thanks, I have two very similar to that... It doesn't help...
Just a side note where this is new to you, you should have run your onboard water pump and filled the entire water system including the water heater to get the entire system sanitized.

It’s common to have the tank burp while filling. Because of the size of the fill hose and the inside diameter of the fill tube, there’s not enough clearance to allow the air to bleed out. You need to use a smaller hose and fill slowly.
Thanks, I'm not new to this... I did run the pump and all water outlets, hot and cold, so all got sanitized..... I really slowed the fill down, and it didn't help.... What gets me, is the the 2 sanitation fills I had no issue... Why on the third fill?.. Almost like the fill tube had a reverse trap in it... The water couldn't get past something...
Butch
 

Rene T

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May 20, 2011
Posts
18,665
Location
Farmington NH
Thanks, I have two very similar to that... It doesn't help...

Thanks, I'm not new to this... I did run the pump and all water outlets, hot and cold, so all got sanitized..... I really slowed the fill down, and it didn't help.... What gets me, is the the 2 sanitation fills I had no issue... Why on the third fill?.. Almost like the fill tube had a reverse trap in it... The water couldn't get past something...
Butch
OK. I read it wrong. You said that you filled the tank twice and then drained it never mentioning about running the pump and you didn’t have to because the issue is with the tank. Sorry about that. 👍👍👍
 

Gary RV_Wizard

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Feb 2, 2005
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At my Silver Springs FL home
As Dutch mentioned, the problem is often caused by water overflowing at the filler tube and running into the vent opening. The vent line sometimes has a low spot or even a kink and the water stays there, blocking further venting. Also, the vent line is often far too small compared to the filler tube.
 

Henry J Fate

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Jun 14, 2018
Posts
1,700
I have a 2001 Winnebago Brave with a 75 gallon fresh water tank that is filled manually with a hose on the side of the MH. There are 2 vents in this design and it is very likely yours is the same way. One is located in the filler tube (tube vent) and the other is located vertically from the tank (main vent) and vents to the ground. The vent in the filler tube is too small for any practical water flow. The main vent is the vent that allows me to fill at a good flow rate. I proved this by adding a ball valve to the main tank vent. This was primarily done to prevent water leaking up and out to the ground when travelling with a full tank. I open that ball valve when filling and sometimes I forget and water will back up the fill tube. The main vent is always closed unless filling. The tube vent is always active even when the access door is closed. The tube vent provides just enough air into the tank as the pump pulls water from the tank into house.

It is possible that there is some sort of backflow preventer on your main tank vent and it could be stuck closed. A backflow preventer may have been activated during your last fill. It will activate as soon as a flow of water hits it. This can happen when the tank is over filled or while driving or the forces push water up into the main vent. Mine did not have a backflow preventer and that is why I installed a ball valve to the main vent which stops the water from being forced up and out to the road when travelling.
 
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Kirk

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Oct 30, 2005
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Full-time , Escapee
As Dutch mentioned, the problem is often caused by water overflowing at the filler tube and running into the vent opening. The vent line sometimes has a low spot or even a kink and the water stays there, blocking further venting. Also, the vent line is often far too small compared to the filler tube.
I have had the low-point issue on 2 different RVs. In both cases I was able to eliminate the water collection by rerouting the vent hose. If you can access the hose just use wire ties or something to fasten the hose so that it has no place that it has any U in the line. If you can make the U inverted, that will resolve the problem permanently.
What gets me, is the the 2 sanitation fills I had no issue... Why on the third fill?
When you started the process there would have been no water in the low-point of the vent hose so air could move freely through it. Probably the second fill was when some water entered the vent line and was enough to fill the hose in that low-point, thus blocking the hose and preventing air from venting from the tank. In time that water will evaporate or you could correct it with some compressed air but removing the low-point is the best solution. If you consider the diameter of the vent hose, it would only take a couple of teaspoons of water to block it.
 

JayArr

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Jun 13, 2020
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861
Location
Mission British Columbia Canada
That happens to me all the time there is a slight dip in the line between where it attaches to the outside wall and where it attaches to the water tank. I just jam the fill hose into the fill hole and turn up the fill pressure and it forces the water in the vent line back out and then it starts filling without the burps.

Don't go slower, go faster!
 

ButchW

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Apr 14, 2021
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97
Location
La Mirada, CA
That happens to me all the time there is a slight dip in the line between where it attaches to the outside wall and where it attaches to the water tank. I just jam the fill hose into the fill hole and turn up the fill pressure and it forces the water in the vent line back out and then it starts filling without the burps.

Don't go slower, go faster!
That's kinda what I did...

I'm thinking that the low point vent is the issue... I will see if it is something easily corrected...

I was boondocking this last week for the 1st time with this MH.... There are some issues that need correcting, but over all I'm pleased with the MH... Much easier than setting up and taking down the 5th wheel... Thanks for the help guys....
Butch
 

CharlesinGA

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Oct 6, 2017
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662
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50 miles south of Atlanta, GA
Jamming a garden hose end in the filler port can lead to disaster. People have blown the flex filler hose off the tank or the filler port (thats me) or swell the tank to such a size as to bend the mounting brackets and have the tank wanting to fall out of the RV. All kinds of problems can ensue. The small air vent next to the filler port is designed to admit air to the tank to replace the water the pump is drawing out of the tank, it is NOT designed to vent air out of the tank when you have a garden hose running full blast into the tank.

I discovered, after the fact, that the owners manual for my trailer (skimpy as it is) actually instructs you to use a reduced filler hose that slides into the fill port and allows air to escape around it. Camco and others make such a filler

1031844

For me, my filler neck hose was cut by the factory way too short, and was unsupported, so the hose had apparently come off before (evidence by my finding an offset screwdriver wedged behind the wire harness adjacent to the filler port on the inside). Anyhow, I replaced the filler hose and strapped it and a new vinyl vent hose (old one had mold in it) up, and now I use a very long adapter I made that reaches all the way to the tank. Granted, this is a unusual situation but these adapters are made for a reason, and that is to keep from damaging the RV.

60 psi can do quite a bit of damage.

EDIT: NY_Dutch said the same thing earlier...............

The problem can occur when the filling water enters the vent tube and prevents air from escaping. A short length of hose that fits in the filler hose will reach past the vent and prevent the water from blocking it. You can make your own or Camco makes a one that works well.

https://www.amazon.com/Camco-40004-Gravity-Water-Adapter/dp/B08HBGD6Z3/

A Bigfoot 25 ft trailer owner swelled up his tank and destroyed his tank supports (by shoving the hose into the fill port). It turned into quite the mess to repair as the tank is inside a fiberglass shroud that is sealed to the frame all around the edges (4 season trailer). My fresh water is inside and the waste tanks have a similar shroud covering them.

First pic shows the final filler hose install. The vent line is mostly hidden behind it, strapped up with it. The second pic shows the filler I made to reach all the way to the tank. Third pic shows the (arrow) mold inside the old vent line. In removing this vent line the nipple on the outside filler broke off and I had to replace the entire filler adapter and door.

Charles
 

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ButchW

Well-known member
Joined
Apr 14, 2021
Posts
97
Location
La Mirada, CA
Jamming a garden hose end in the filler port can lead to disaster. People have blown the flex filler hose off the tank or the filler port (thats me) or swell the tank to such a size as to bend the mounting brackets and have the tank wanting to fall out of the RV. All kinds of problems can ensue. The small air vent next to the filler port is designed to admit air to the tank to replace the water the pump is drawing out of the tank, it is NOT designed to vent air out of the tank when you have a garden hose running full blast into the tank.

I discovered, after the fact, that the owners manual for my trailer (skimpy as it is) actually instructs you to use a reduced filler hose that slides into the fill port and allows air to escape around it. Camco and others make such a filler

1031844

For me, my filler neck hose was cut by the factory way too short, and was unsupported, so the hose had apparently come off before (evidence by my finding an offset screwdriver wedged behind the wire harness adjacent to the filler port on the inside). Anyhow, I replaced the filler hose and strapped it and a new vinyl vent hose (old one had mold in it) up, and now I use a very long adapter I made that reaches all the way to the tank. Granted, this is a unusual situation but these adapters are made for a reason, and that is to keep from damaging the RV.

60 psi can do quite a bit of damage.

EDIT: NY_Dutch said the same thing earlier...............



A Bigfoot 25 ft trailer owner swelled up his tank and destroyed his tank supports (by shoving the hose into the fill port). It turned into quite the mess to repair as the tank is inside a fiberglass shroud that is sealed to the frame all around the edges (4 season trailer). My fresh water is inside and the waste tanks have a similar shroud covering them.

First pic shows the final filler hose install. The vent line is mostly hidden behind it, strapped up with it. The second pic shows the filler I made to reach all the way to the tank. Third pic shows the (arrow) mold inside the old vent line. In removing this vent line the nipple on the outside filler broke off and I had to replace the entire filler adapter and door.

Charles
I have a couple of those typ fillers... Maybe the longer hose like the one you made would make a difference... I wasn't sure where the vent attached to... The tank or just intercepted the fill hose in a little ways... I see from your pics, that it goes all the way to the tank... I'm thinking that my vent tube got plugged during the sanitizing process... It's been at least 6 months since any water was in it (Maybe longer, as I bought the MH 6 mos. ago), and who knows what condition the tank was in...
Butch
 
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