I'm assuming you have the gravity fill type of water inlet to fill the fresh tank, as opposed to the 4-way Anderson Valve.
There may be a small vent next to the gravity fill inlet. Use a short piece of hose or tubing to blow air into the vent. That will clear any water stuck in the vent line.
If it still backs up, you may have a low spot where the hose sags between the inlet and the connection to the fresh tank. You'd have to poke behind walls and above the coroplast to investigate that possibility. Or if in warranty, your dealer can. Or if it's easier and less expensive to pay the travel charge for a mobile servicer, call Heartland to get approval in advance, to use the mobile servicer for warranty.
You may also have fresh tank overflow drain(s) coming out the sides along the frame, terminating in a 90 degree PEX fitting. If so, you may be able to use the PEX fitting as an alternate fill inlet. You'd need rig up some fittings to connect the hose to the PEX. Metering the water being added will help avoid overfilling. Inexpensive garden hose meters can be purchased from Amazon and other places.
This is how I fill my fresh water tank and haven't had any problem. On the TT there is just the fill hose and a vent line that sits beside the fill so as the tank gets full the vent will have water overflowing, but filling the tank too fast without the short flexible water hose as suggested and I get backflow.You might try cutting a short piece off the end of a flexable garden hose (about 16 inches) leaving the female connector so you can connect it to a regular hose end. You can then feed the cut off end into the gravity fill a short way. The fill line usually makes a turn just inside the fill opening. I had the same problem and this worked for me.
appreciate your help, when you say blow air, do you mean compressed air or by mouth?
This is how I fill my fresh water tank and haven't had any problem. On the TT there is just the fill hose and a vent line that sits beside the fill so as the tank gets full the vent will have water overflowing, but filling the tank too fast without the short flexible water hose as suggested and I get backflow.
You might try cutting a short piece off the end of a flexable garden hose (about 16 inches) leaving the female connector so you can connect it to a regular hose end. You can then feed the cut off end into the gravity fill a short way. The fill line usually makes a turn just inside the fill opening. I had the same problem and this worked for me.
For future reference: on gravity fill tanks, if you use a pressurized fill, which is essentially what you're doing with the hose tight in place, it's possible to overfill and rupture the tank unless there's an overflow drain - which you may have. So some care is required, and it would be good to check for overflow drains.Much thanks to you and all who responded. I tried somewhat of a combination of all the suggestions; I make up the 16 inch garden hose piece and it work fine but only after pushing the female end of the hose up TIGHT
to the black fill hole and holding it firmly in place during the fill. I'd estimate only about 2-3 percent of water returned and the rest went into the FW holding tank. I opened the valve on the hose only a little bit so it took about 10 minutes to get 2/3 full but that's ok with me as long as it worked. Part of my original problem was that I was expecting to simply place a hose a short distance into the fill hole and that would simply put water into the tank. Obviously, like many
other issues with these TT's there seems to be a particular understanding of how they work and a particular knack at applying the solution.
Again, thanks to all for your experienced suggestions to this newbee traveler.
For future reference: on gravity fill tanks, if you use a pressurized fill, which is essentially what you're doing with the hose tight in place, it's possible to overfill and rupture the tank unless there's an overflow drain - which you may have. So some care is required, and it would be good to check for overflow drains.