Fresh Water Tanks Expanded-An Expensive Lesson

[Lynn1130]

I may have created a very expensive repair for myself. I began filling the freshwater tanks much as I have in the past. I usually only turn the fill hose on to about 1/2 feed because I know that the crossover on these tanks is slow to equalize and I try to stay close until it is near full. I got busy with something else and then realized that water was back-washing from the fill port. I shut the water off, pulled the hose and got a bunch of blow back from the freshwater fill. Sometime later I had a leak from the now drooping belly cover and after dropping the cover found that the tanks were expanded, the bracing straps were broken and the ply support was bowed and cracked. The crossover was leaking from both ends. The pressure went down which I guess was better than up but I am now told that the 3/8 inch vent is inadequate for the 1/2 inch flow coming in and the hydraulic pressure created can cause the issues I have.

I know that there are several threads on related issues but it seems that my only solution now is new tanks and repair of the support damage. I have also been told by my repair shop that fitting the new tanks with a 1/2 inch vent will help prevent this from happening again.

I'm crying in my beer tonight.

 

[TandT]

Lynn, I'm feelin' for you. At least you have a beer. It'll get better.

After a couple of close calls, I have gotten into the habit of not leaving the UDC if anything at all is going on there. Trace

 

[porthole]

Finish your beer, relax and just plan on doing some work.

The 3/8" vent is sufficient as long as you are not trying to fill them to the max at a high flow rate. You should have three vent lines.
The crossover leak, although not normal is not unheard off.

Can you do the work?
Remove the underbelly and get a good look at how things are laid out.
You can search fresh water tanks on the forum for ideas on what several of us have done in regards to new supports.

Typical though is to scrap the 1/2" OSB that is holding the tanks now and replace it with two laminated pieces of 1/2" plywood or a single 3/4" piece of plywood.

Make new support bars and you will be OK.

Re-doing the vent and fill lines would be a good idea while you are under there.

 

[Lynn1130]

Unfortunately I have no place to do the work. I can't leave it on the street for over 72 hours (law) and cannot do the work in the storage yard (rules). It is too hot to work on this right now anyway. So, it goes to the RV repair shop for the work. They suggested the change in the size of the vent line. What change can be made to the fill line? Is it better to go to the manufacturer for tanks or to Heartland (costs)?

I read through some of the threads on this topic but information is scattered over several and difficult to organize. Other than the fill, vent, and support ply what recommendations do you have?

Thanks

 

[porthole]

What makes you think you need tanks? Did you find a hole or crack in the tank?
Tanks are big, won't be cheap to ship. About 60 x 30 x 12 IIRC.

 

[Lynn1130]

I don't think the tanks have any holes but they have expanded. Can I get by with fixing any leaks from connections as well as the braces and ply?

 

[Invizatu]

I would give that a try first and see how it works. Those tanks are pretty durable.

 

[jnbhobe]

Do as Duane says, plywood,raise the vent line to the top high above the tank,take any slack out of the fill line, and I would bolt a piece of channel or angle iron to the frame rails under the tank. I travel with a full tank of water all the time with out any problems.

 

[RAHanock]

I don't think the problem is the size of the vent line. I can use a fast fill rate as long as the vent is venting air. When the air vent line fills with water, which happens often, the pressure will build in the tank and you won't be able to remove the water in the vent line due to the back pressure.

I have a two foot length of tubing that I hold against the vent port next to the gravity feed port that I use to blow out the water in the vent line as I fill the tank. It takes doing this about 3 or 4 times during filling. And I can sense (feel and/or hear) the air escaping from the line if I leave the tube against the vent port. When I don't sense air escaping, it's time to blow out the line again. This method works well for me and I can always get near the full capacity of water into the tank.

 

[Bob&Patty]

Just to add a note on the tanks. They are made to expand. Do as others explained. Build a new support for under the tanks. Raise the vent hoses as high as possible. Remove any kinks in the fill hose. If the tanks themselves are not leaking, they do not need to be replaced. You should be able to do the repairs in a day at your home.

 

[Lynn1130]

This may turn out to be less of a problem that I thought. The tanks are in good shape. There is, however, an issue that I have to resolve with Customer Service. It appears that fittings on the tanks have been leaking for some time as the ply is rotted and moldy. The fittings were put in with some sort of "lube" rather than seal. We will see how this progresses but the leaks are very likely an install issue. Oh, and one other interesting note. The "ply" is the cheap particle board rather than "real" plywood. That's disappointing.

 

[porthole]

Oriented strand board, AKA "OSB". Nothing but chips of wood glued together. Really not he best product to use to support tanks.
Those of us that are concerned have removed the OSB and replaced with plywood.

The OSB does not hold up well to either a load or moisture. Exterior grade plywood will go a long ways to wards making a good support platform. And adding a piece of angle as Jon suggested when you are all done will help even more.

The tanks are about 55 gallons each. Full, that is approximately 470 pounds you are trying to hold up.

 

[Lynn1130]

OK. Here is the final on this fiasco. The tanks were not damaged and were reused. Several of the fittings were loose and leaking, including the crossover. One or more had been leaking for sometime as there is rust on the wood from the metal braces and mold on the wood. Remember, we have 10% or less humidity here most of the time. It takes some amount of moisture and time to cause what happened here. So these leaks were going for awhile. Here is what was done.

All fittings were sealed properly.

All fittings on the tank are clamped with hose clamps around the female receiver (I don't know how else to explain this) to prevent the tank receiver fitting from cracking over time from movement of the incoming lines. Sorry if this is confusing but for anyone who has had to pull a tank and send it out to have a new fitting welded in because the fitting cracked, you know what I mean. This is a common issue with RV tanks.

The three vents that had vented to the UCD now vent, individually, out of the bottom of the belly of the rig. This accomplishes two things. There is no water sloshing out of the vent in the UCD and getting everything there wet and each tank vents on it's own rather than all joined to one very small hose. It worked well on the test fill. There is no chance of kinked or flooded vent lines.

All OSB was replaced with ply.

I promise in the future to mind my water fill and not get distracted. Even though it appears that that had only a small amount to do with the problems that were fixed.

 

[porthole]

If you think you may get distracted filling 100+ gallons - what I do is when I get tired of waiting, I close the water flow to a much smaller steam. Then when when the tank is full the vents have no issue bleeding off the displaced air and the tanks don't get stretched outside of what is normal.