RV fresh water question

[slickpuss]

Has anyone had to deal with an airlock type of situation on their RV water tanks? I fill and fill my fresh tanks till it comes out of the overflow. When Im camping I run out once ive used about 40 gallons. I should have 100 gallons of water to use. I know the level sensors arent very reliable, but the fresh water never shows above 3/4 full. Im thinking that they are getting air locked somehow. I thought I saw the overflow coming out of the side of the tank, seems like it would be more appropriate to have it come off of the top.

Any tips or suggestions?

 

[Chili]

I've got an old RV, it doesn't have an overflow on the tank. I was having issues where I thought the tank was full and after very little usage at the track I would be out of water. What was happening was when I filled the tank, sometimes the water was coming too fast out of the line and it would get some back pressure and start to back up like it was full. If you took the hose off and put it back on at very low pressure it would take substantially more water. At home I've simply started filling the tank from inside the RV, It's under the back bench right near the door so I just pop the seat up and fill it up through the large cap at the top of the tank. It's also easier because access to the normal fillup is very difficult because that side of the RV is tight to the fence. When filling up on the road we still use the conventional method.

 

[nikki]

After it comes out of the overflow, let it sit for a minute or two, then try adding more water. Especially if you have 2 - 50 gallon tanks, sometimes it takes a little for the water to get through where they connect. You may be filling faster than the water can settle in the tanks. Also, we usually look at the fresh water tanks under the rig to check their level, instead of relying on the guage, when filling up.

 

[slickpuss]

Good points from both of you. I do have 2 50 gallon tanks. They are black plastic though, so I cant visualy tell if they are full. I climb underneath and bang on them to tell how full they are, but I really cant tell to good by that. At just 20 gallons in each, what is that, like 160lbs or something. They just seem really heavy and hard. But I usually just stick the filler hose in there full blast while i load everything else. Ill try to add slower at the end and see how that does.
I really hate to find out mid shower that I actually only brought 40 gallons instead of 100. Which has happened too many times allready.
Thanks for the info

 

[kmccune]

Camper water fills tend to back up if you try to fill too fast. Turn down the flow a little.

 

[oldguy]

We ran into a problem where the tanks airlocked while filling to fast and actually expanded enough (like a big hard ballon) to snap a couple welds on the support structure. Since then I only trickle the water in slowly and check often to make sure the air is bleeding out.
Once I find some time I am going to put in an air bleed line to both tanks with some 1/4 in flexible hose
Our problem is mainly the rear 50 gal tank filling above the pipe that connects to the front 50 gal tank and blocking the air from escaping.

 

[slickpuss]

Just an update for anyone who has a Attude trailer. I found that the overflow hose is mounted at about half of the tanks level. So the fresh water tanks would never fill above 1/2 before overflowing. I fixed this by pulling out the 90 that was screwed into the tank and glueing in a nipple about 3 inches longer. Now the water fills the tanks before I get any overflow.

Jeez, im very suprised by the brainless engineering that goes into some new trailers. Or perhaps its just the installation crew.