Filling Water Tank

[Jbug]

I just bought a Carbon 337 fifth wheel. When filling my water tank, a sticker says to open the gravity fill cap. Where is the gravity fill cap? Thanks for any help you can offer.

[canesfan]

Ok, I have to ask a really stupid question...if you are filling your water tank and have a gravity fill, wouldn't you be using the gravity fill to fill it??? Sigh, who knows what they did on this unit. Are you using the city water inlet to fill the tank with a valve for either city water or tank fill? If so then there would be a small vent somewhere. Even if not there should be a small vent somewhere. IF there is a gravity fill, it could be located anywhere, even behind a small square door with a lock on it. The vent is usually located near the gravity fill...IF one actually exists. I don't have the luxury of a gravity fill, and my vent is on the opposite side of the rig that the docking station is.

[Jbug]

There is a water supply hook up that the hose goes into. It is normally the city water hookup, but when filling the tank you turn a knob so the water goes into the tank. So I assume the sticker is talking about some other gravity fill cap where air can be released when filling the tank with water, and possibly where water would overflow.

[Sandi587]

On our 404 there is a small 4 inch square locking door about a foot to the right of the utility center where your hook ups are. Behind the door is the gravity fill.

[gearhead]

Or...it could be near the freshwater tank which usually is at the rear. May be a small 2" x 2" plastic cover that will slide off upwards. Maybe be a metal screen inside. It will vent or can be used to fill by loosely putting the end of a hose in the vent. Go easy, don't open the water wide open and leave some room around the end of the water hose so the tank can vent while you fill.

[Teamster81]

I was just camping next to a friend with a newer Brookstone and he was having trouble filling his tank. It took us a while to figure out after you switched the valves to fill there is also a small round cap above the controls you have to unscrew the cap off while filling. You also have to put it back on before the pump can build pressure.

[MattE303]

I just bought a Carbon 337 fifth wheel. When filling my water tank, a sticker says to open the gravity fill cap. Where is the gravity fill cap? Thanks for any help you can offer.
What year is your Carbon? We just bought a '17 Carbon 337 and ours doesn't have a gravity fill (I wish it did). Ours has a "tank vent" located right above the hot water heater access panel (just to the right of the docking station). The vent has a black cover, rounded on top, square on the bottom 3 sides, open on the bottom. You can slide the cover up to remove it, and there will be metal screen over the opening, but there's no reason to do so when filling via the city water hookup, the cover doesn't block the opening. Basically it's what gearhead described, you can use it to gravity fill, if you're really careful.

[Jbug]

Thanks for the replies. I have a 2018 337. I believe MattE303 is right. There is a tank vent under a cover above the hot water heater. The sticker says open the gravity fill cap, but I don't think there is one.

[gearhead]

If you don't have a gravity fill/vent, how will you disinfect the tank?

[chuckster57]

I was just camping next to a friend with a newer Brookstone and he was having trouble filling his tank. It took us a while to figure out after you switched the valves to fill there is also a small round cap above the controls you have to unscrew the cap off while filling. You also have to put it back on before the pump can build pressure.

RV water pumps do not pressurize the fresh water holding tank, the PULL water from the tank and pressurize the water lines in the coach. Perhaps the valves weren't turned the right way.