Fresh h2o tank sucking air

[Tim2542]

My fresh tank has begun to suck air when only 1/2 empty or so, a new development. Any tips on where to look before I tear into it? I suspect Im going to have to open the bottom and find the tube going into the tank. This on a 310 Solitude Thanks

[howson]

My fresh tank has begun to suck air when only 1/2 empty or so, a new development. Any tips on where to look before I tear into it? I suspect Im going to have to open the bottom and find the tube going into the tank. This on a 310 Solitude Thanks

That's an odd one, Tim2542.

This is one for Cate&Rob , but he's currently traveling so he may not respond promptly.

There's lots of other really smart people that are regulars here, too, and I'm sure they'll chime in if they can think of something.

Welcome to the forum!

-Howard

[Cate&Rob]

My fresh tank has begun to suck air when only 1/2 empty or so, a new development. Any tips on where to look before I tear into it? I suspect Im going to have to open the bottom and find the tube going into the tank. This on a 310 Solitude Thanks

Hi Tim,

Latest production GDRV products have a connection to the fresh water tank that comes off the absolute bottom of the tank. I think that your Solitude would be like this. You could pull down a small section of the coroplast underbelly above the axles on the left side to confirm that this is the type of connection to the tank that you have. If this is the case . . . the problem is not related to the amount of water in the tank. I suspect that there is some other reason that air is getting into the intake side of the pump.

Rob

[TucsonJim]

Just to clarify Rob's photo. The blue line running along the bottom of the tank is the fresh water connection. The blue line running up, over, and down is the over-flow pipe.

If you are gauging "only 1/2 empty or so" on the panel lights, they are usually very inaccurate. I'd place water in the tank and start drawing it down until you notice air coming into the lines. Then, I'd place a five gallon bucket under the fresh tank drain and measure how much water is left. You may have to fill the bucket and dump it a few times if there is still a significant amount of water remaining.

Once you know how much water is still remaining when it sucks air may point us into different diagnostic paths.

Jim

[Yoda]

By sucking air are you referring to the water pump cavitation and air coming from the faucets? If so on the front of your pump is a filter screen with clear dome. Check to be sure there are no cracks and the dome is tight on the fixture. If not air can be pulled in by the pump. Also check all pump fittings for tightness. Last question - did you install a valve in the overflow to prevent loss of water while traveling? If so make sure the valve is open.

Hope this helps

[Tim2542]

Thanks for the suggestions. Yes this a 2019, and yes, Im sure the tank still has significant water in it when it begins to pick up air. Thanks again!

[Floyd&Tamily]

I have a similar issue on my 2018 Momentum 328M. I have to have at least 30 gallons of water in my tanks to get steady flow out of the pump. I always have bubbles in the strainer glass, but water flow is not affected as long as I have 30+ gallons in the tank. The pump and strainer have both been replaced with no affect. There are no external water leaks visible. I can only assume I have a restriction or leak on the inlet side somewhere. But that doesn't really explain why it works with more water, unless it has to do with head pressure increase by the volume of water. Just spit balling!

[Cate&Rob]

If you can “fix” the problem by increasing the water level in the tank, it would seen that the problem is the distance between the end of the pick up tube and the bottom of the tank.

Rob

[Floyd&Tamily]

That was my first thought and question to GD, but they are telling me that the pickup is just like your photo you posted above. I haven't physically investigated the plumbing to the tank yet.

[Cate&Rob]

Floyd&Tamily

This is a very curious situation. Somehow, higher water level in the tank is covering what is otherwise an air leak into the intake side of the pump. This could be a cut in the line heading in an upward direction from the tank to the pump . . . but, this should leak water with a full tank and you have already ruled this out. It takes a lot to stump me on a plumbing question . . . but, I don’t have an explanation for what you describe. Over to others ???

Rob

[howson]

Floyd&TamilyOver to others ???

Rob,
Well, that's obviously me, right?

Totally from left field--look at https://gdrvowners.com/forum/operati...el-information and note how the "Dry Camping" water path (theoretically) works. Could air be getting drawn in at the black lever connection? It's between the tank and the pump.

Why does it work with >30 gallons? I can only guess because it takes less pump power to pull water out of the tank, thus little to no air from the poor connection at the black lever on the Nautilus panel.

What do you think? Any chance that could be an issue?

Howard

[Cate&Rob]

howson
Hi Howard,

I am open to any ideas on this . The problem that I can see with your theory is that if air can leak in, water can (usually) leak out. If there is a leak at this valve that lets air in, it should also let water out when the pump is off. This has reportedly not been the case. It is possible that there is a "flapper valve" affect going on here and the seal at this valve will allow air past the valve seal in one direction but not let water out past this seal in the other direction. The really curious thing about this is how higher water level in the tank (which is still much lower than this valve) can "fix" the problem.

Rob

[Guest]

Agree with Floyd's suggestion that the head pressure is helping to overcome a small air leak on the suction side. Once the head pressure is reduced, the pump pulls in air. Could start by removing the pump and testing it outside the rig with a bucket of water and at different heights on the suction side. If the pump is functioning properly, disconnect and cap off the line at the tank, pressurize the system at the pump inlet to locate the leak.
Jim

[Floyd&Tamily]

Thanks for all the feedback and ideas. I will be looking into this and will report back with any findings.

[JBill9694]

This may be a little out there for an RV fresh water pump, but here I go anyways. Pumps have something called a Net Pressure Suction Head. Basically this means if the pump or the pump intake does not have enough submergence for the amount of water it is pumping and the head it is pumping against then the water surface can be drawn down to where the pump starts sucking air. A couple of ways to combat this problem is to not pump as much water, or to increase the pressure that your pumping against. With a single speed pump it may be easiest to place a restriction (valve or section of smaller diameter hose) in the pump's discharge line.