Help! Air lock in fresh water fill pipe or tank?

[archeogal2]

We are having a pesky problem filling our fresh water tank over the past few months. When we begin filling it as usual with a hose, the water very quickly begins to run nearly full stream back out the opening, and proceeds to do that until there is something like a "burp", and some air comes out, and then more water will go in for a while, then another burp, and so on. The result is that it takes 3-4 times as long as it should to fill the tank, and meanwhile the people in line behind us are tapping their feet and wondering what is wrong with us. We are not newbies, but not good mechanically, and don't know where to start to address this problem. It seems to have just started this season, so maybe could have something to do with how the valves were turned or not turned during winterization? Not sure how so much air can get into the tank. Any advice will be appreciated, both by us, and those poor people behind us.



2015 Great West Van Classic on Promaster (one of the last out of the GWV Alabama factory before the closure)

[avanti]

Sounds like the air vent tube for the fresh tank is clogged or non-existent.
If it is like our 2014 Sprinter-based GWV (the FIRST out of the Alabama plant), there should be a 1/4" clear plastic tube that runs from the top of the fresh tank to the little round screen thing next to the water fill port. Its purpose is to let air in and out of the tank as the water level changes. Sounds like yours needs attention.

[GeorgeRa]

I had a very similar issue on my Bigfoot trailer with very similar gurgling symptoms. As mentioned by Pete check your tank vent tube, it should connect top of the water tank with the filler port. If this tube sags it will form a hydraulic u-tube and in case of overfill this u-tube will fill water and block venting with a few inches of water back pressure. Best solution is to lift the middle of the tubing to eliminate u-tube formation. On my trailer a cable zip tie eliminated the u-tube killed the issue.

[DUTCH in Atlanta]

Originally Posted by avanti

Sounds like the air vent tube for the fresh tank is clogged or non-existent.
If it is like our 2014 Sprinter-based GWV (the FIRST out of the Alabama plant),

Which Alabama plant?

[avanti]

Originally Posted by DUTCH in Atlanta

Which Alabama plant?

Long, sad story. In early 2014, GWV was lured from Winnipeg to rural Winfield AL. They were given attractive incentives and set up in a nice, new plant. Worked out poorly for all involved and they were soon out of business.

[archeogal2]

Originally Posted by avanti

Sounds like the air vent tube for the fresh tank is clogged or non-existent.
If it is like our 2014 Sprinter-based GWV (the FIRST out of the Alabama plant), there should be a 1/4" clear plastic tube that runs from the top of the fresh tank to the little round screen thing next to the water fill port. Its purpose is to let air in and out of the tank as the water level changes. Sounds like yours needs attention.

Thank you, Avanti. Will look for this.

Archeogal2

[archeogal2]

Thanks! This is helpful! Now if one of us can just manage to get under this low-low van. . , will let you know what happens.

[avanti]

Originally Posted by archeogal2

Thanks! This is helpful! Now if one of us can just manage to get under this low-low van. . , will let you know what happens.

Build a set of these:

Lift f.jpg

Lift.jpg

You will be glad you did.

[tangofiend]

Open a cold water tap to let the air out. Same when filling hot water tank.

[georgeherberger]

go online and search for a ""Water Heater Tank Rinser", put it on the end of your fill hose and the air in the tank will come out without burping all over you. works like a charm.

[archeogal2]

We have tried opening either or both faucets. That helps some, but not a lot.

[archeogal2]

We have tried opening either or both faucets. That helps some, but not a lot.

[archeogal2]

Just looked at the water heater tank rinser tool. Thanks for the tip. It might help the symptom. We think that the vent pipe as suggested by a couple of you above is the likely problem. Crawled under the van and our underneath is so crowded that we cannot see the vent tube.for the fresh water tank. For the short term we’re living with it as we’re on the road. Will likely take it to our local repair place when we get home. But if we happen on a RV parts place we will try the hot water tank rinser. Thanks to all for your thoughts.

2015 Great West Van Classic on Promaster

[archeogal2]

]Just looked at the water heater tank rinser tool. Thanks for the tip. It might help the symptom. We think that the vent pipe as suggested by a couple of you above is the likely problem. Crawled under the van and our underneath is so crowded that we cannot see the vent tube.for the fresh water tank. For the short term we’re living with it as we’re on the road. Will likely take it to our local repair place when we get home. But if we happen on a RV parts place we will try the hot water tank rinser. Thanks to all for your thoughts.

2015 Great West Van Classic on Promaster

[GeorgeRa]

You should be able to test the vent line by trying to blow air from your mouth through about ½” diameter tube reasonably well sealed at the vent opening. You should feel very little resistance. High resistance will tell you if there is a blockage. If the passage is blocked by water in the u-tube like vent tube you could blow this water back into the water tank.

In addition see this writing, you are not alone.
Solving RV Slow Fresh Water Tank Fill | PopUpBackpacker

[GeorgeRa]

Originally Posted by GeorgeRa

........................

In addition see this writing, you are not alone.
Solving RV Slow Fresh Water Tank Fill | PopUpBackpacker

I wouldn’t follow this Water Bandit recommendation, it can cause problems. Sealing water entry can cause pressure buildup inside the water tank if venting is insufficient. For example, a 20 gal tank side wall could have 16” edge dimension with fully symmetrical tank. With that size and shape tank buildup of 3 PSI inside will push a side wall of the tank with 50 lbs. or at 5 PSI with 80 lbs. These number will change a lot with different tank shapes.

I had once this problem with our Bigfoot Camper. The fill hose diameter was too large and sealed the water inlet consequently causing pressure buildup inside the tank. This pressure caused major damage to the table mount located on top of the water tank, it took hours to repair.

My current van has pressure fill system but I paid a lot of attention to allow sufficient venting, restricted water flow, and reduced pressure to 25 PSI. The vent has ¾” NPT ½ PSI pressure relief valve.

[avanti]

Originally Posted by GeorgeRa

You should be able to test the vent line by trying to blow air from your mouth through about ½” diameter tube reasonably well sealed at the vent opening. You should feel very little resistance. High resistance will tell you if there is a blockage.

Yes.
Also, if you (carefully) overfill your tank using a hose, water should spurt out that little hole. If it does't, that is another piece of evidence of a blockage. (BTW: You should do this while sanitizing your tanks, so that the tube gets sanitized).

Of course, in the chaos of GWV's death throes, maybe they never installed the vent.

[booster]

Originally Posted by GeorgeRa

I wouldn’t follow this Water Bandit recommendation, it can cause problems. Sealing water entry can cause pressure buildup inside the water tank if venting is insufficient. For example, a 20 gal tank side wall could have 16” edge dimension with fully symmetrical tank. With that size and shape tank buildup of 3 PSI inside will push a side wall of the tank with 50 lbs. or at 5 PSI with 80 lbs. These number will change a lot with different tank shapes.

I had once this problem with our Bigfoot Camper. The fill hose diameter was too large and sealed the water inlet consequently causing pressure buildup inside the tank. This pressure caused major damage to the table mount located on top of the water tank, it took hours to repair.

My current van has pressure fill system but I paid a lot of attention to allow sufficient venting, restricted water flow, and reduced pressure to 25 PSI. The vent has ¾” NPT ½ PSI pressure relief valve.

This is a good point on accidentally pressurizing the tank when filling it from a hose.


This exact issue is very possible, probable even, on our 07 C190P Roadtrek when we fill with a garden hose at the door pillar port. The size of the port is such that the hose end fits it very tightly and will completely close it off to air bleed or tell when it is full. If that happens unnoticed and you pull the hose out, you are guaranteed to get a shower a it will belch back a lot of water.



I would think you could also overpressure the tank and damage it so have to be careful.

[avanti]

Originally Posted by booster

The size of the port is such that the hose end fits it very tightly and will completely close it off to air bleed or tell when it is full.

Yes. For this reason, it is best to always use a hose nozzle, which reduces the diameter and leaves some room for backblow:

[Doneworking]

I have used one of these for years:

https://www.walmart.com/ip/Water-Fil...iller/23500597

I have, however modified it in two ways:

1. I tape a piece of 1/4 inch ID tubing about two inches longer than this filler to the filler vinyl hose and let it extend behind the valve area a couple of inches. This allows air to access the rv fill tube and helps prevent blow backs.

https://www.homedepot.com/p/Abbott-R...7005/302094913

2. I put the end of both the tubing on the filler and the little 1/4 air tube into a flame for a few seconds to heat it and melt it only slightly (which rounds the edges a bit) so that no edges on either tube are sharp and thus help prevent puncturing or damaging the fill hose on the rv.

I have done this for years for several different rvs.