Sometimes when the hole is cut for the drain nipple, the piece cut out is "lost" in the tank. When the water runs out, especially when the level gets low, that piece will settle over the hole and block the drain. I would guess the only way to see and/or remove it would be to disconnect the drain at the tank and try to look up of feel up inside. I would expect the nipple to be short enough to at least get a finger up inside.
I had the same problem with my gray tank, and yes when one of the holes for the vent and drain lines are drilled this pieces some times fall into the tank. The good news is that the drain is 4" in dia. and not that hard to get off, so one can get their hand inside the tank to get something like this out, should be at the low where the drain is, mine was.
charlan wrote: this is commonly used in trailers, no roof stack required
(for sinks only).
This is most likely not a vent for the gray tank. It is probably a siphon breaker that prevents the water from being sucked out of the trap when the sink is drained.
Both my SunnyBrook fiver and Lance TC have these on each sink. They are siphon breakers, they let air in but not out. In addition both units have roof vents for all of the respective tanks.
Why would you vent a gray tank that has the possibility of producing foul odors in a living area. On second thought, if its vented inside why would you need the trap to start with.
ryoung
2004 Dodge 3500 Dually HO 6 sp 4.10, Jordan Controller
2005 SunnyBrook 31BWKS
2004 Lance Lite 915
My current trailer, a SB, has a vent stack for each tank and vacuum breaker's on each of the sinks and the shower.
My guess is a critter/bug nest is blocking the vent stack or the vent is inserted to far into the tank causing it to lack airflow when you fill the tank past the vent insert point.
Michael 2 DD's and my DW 6 Acre's of Maine 2009 Crossroads Cruiser CF31SB 2008 Chevy 2500HD Ext. Cab LT 4X4 Champion lil' yellow Chinese genset, 4000W Camping Pictures
My Cruiser has a vent for the galley tank under the sink similar to the one in Charlans post. My water heater is under the sink so the drain pipe runs horizontal from the sink cabinet behind the stove and then down thru the adjacent cabinet. I figured it out one day when I noticed there was no roof vent. I originaly thought the pipe in the back of the adjacent cabinet was the vent pipe but it actually is the drain pipe. I've noticed the galley tank drains a bit slower than the other gray tank for the shower.
Patrick (aka Shoetravel)
The wife, the 2 sons, and the daughter with me enjoying the outdoors of WA.
2005 Crossroads Cruiser CF29RE pulled by an '04 Ford F-250 crew 6.0 P/stroke FX-4.
charlan wrote: this is commonly used in trailers, no roof stack required
(for sinks only).
This is most likely not a vent for the gray tank. It is probably a siphon breaker that prevents the water from being sucked out of the trap when the sink is drained.
Both my SunnyBrook fiver and Lance TC have these on each sink. They are siphon breakers, they let air in but not out. In addition both units have roof vents for all of the respective tanks.
Why would you vent a gray tank that has the possibility of producing foul odors in a living area. On second thought, if its vented inside why would you need the trap to start with.
ryoung
AAV valves can be used in lieu of expensive and complex plumbing (open pipe) vent systems that penetrate roofs of buildings.
- The purpose of vents is to allow air to enter the plumbing drainage waste and vent system and equalize pressure when water drains out of the system maintaining the integrity of the water trap that prevents sewer gases from entering the building through fixture drains.
- When a plumbing fixture is operated, negative pressure causes the AAV to open, allowing air to enter and equalize the pressure in the system. When the flow stops, gravity closes the valve preventing sewer gas from escaping through the valve into the building.
If you GT Vent is stopped up, it is likely that draining the grey tank will suck some or all of the water from the P-traps of any fixture emptying into the grey tank and could cause some odor issues. Not near as big a deal as the black tank, but could also be the source of the "glug glug"...
08 Carriage Cameo F34CK3
07 GMC Sierra 2500 HD 6.6 Duramax
00 Chevrolet Tahoe (retired T/V)
55 Beautiful, brunette RV loving Wife
06 Cavalier King Charles Spaniel "Roxy"
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