I can not find the fresh water over fill / air vent on 311BHS

[TenOCPlus]

Getting ready for our first boon docking trip in our new to us 311BHS. This week will be de-winterize and filling up the fresh water tank. I can not find the fresh water over fill / air vent. . . . . . . I know where the fresh water drain is but not the overflow vent. I think I could full tank until water runs out some place, but I would like to know where the water is going to come out so I could plan for the overflow.

[Skilletface]

The overflow pipe should be blue, near the freshwater drain valve and the low point drains. Just a suggestion, you may wish to add some type of valve on the overflow pipe when you locate it. Ours acted like a siphon while underway and would only have a 1/4 tank of fresh water.

[TenOCPlus]

Ours acted like a siphon while underway and would only have a 1/4 tank of fresh water.

Thanks I found it. The previous owner have modified it so it was hard to find. I have read other post that talked about the siphon effect. But I do not understand how SIPHON works, IF THE VENT/OVERFILL hose is above the "normal" water level of the tank.

[OshawaDave]

Thanks I found it. The previous owner have modified it so it was hard to find. I have read other post that talked about the siphon effect. But I do not understand how SIPHON works, IF THE VENT/OVERFILL hose is above the "normal" water level of the tank.

just REMEMBER to open to open the valve when filling your fresh water tank......don't want it to rupture.

[Skilletface]

Thanks I found it. The previous owner have modified it so it was hard to find. I have read other post that talked about the siphon effect. But I do not understand how SIPHON works, IF THE VENT/OVERFILL hose is above the "normal" water level of the tank.

The previous owner may have already modified the overflow to correct the siphon effect, try filling your freshwater tank first before doing anything. This siphon thing is an issue for some and there were different ways to modify the overflow tube. The only reason I put a shark bite valve on was because I had one laying around. Mine stays open most of the time because I rarely travel with more than a 1/4 to 1/2 tank of freshwater.

[sirtate]

I've discovered that if you find a way to 'burp' the overflow pipe, you can shut down the siphon.

With my 261BH, I can fill from either the gravity port or the Wet Bay until the overflow starts to piddle out.
After shutting off the water, it would continue to siphon for a number of minutes until the tank water levels dropped below the pickup for the overflow, leaving a significant amount of water on the ground.

By standing on the steps without the stabilizers extended, I can rock the trailer enough to slosh the water in the fresh tank, you can hear this by listening to the gurgling noises coming out the gravity fill port.
If I do this when the overflow is flowing, I can slosh the water far enough so a bubble of air gets siphoned up the tube, killing the siphon.
Otherwise, as you all know, I drive along leaving a trail of water (and tears over lost showers) behind me.

[TenOCPlus]

I do not think my 2021 reflections 5th wheel Model 311 BHS has a gravity fill port. AM I WRONG??? ...

[WhittleBurner]

I do not think my 2021 reflections 5th wheel Model 311 BHS has a gravity fill port. AM I WRONG??? ...

No you are not wrong, even though we have a different water panel our '14 303 dose not have a gravity fill port either....and I do miss having one