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Old 08-05-2016, 01:21 PM   #15
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The smell -- do you have a black tank rinse system? If so, the system incorporates an anti-siphon valve with a check valve connected to it immediately downstream. When the system is not flushing, the anti-siphon is open to atmosphere under your sink, and the check valve is closed. Maybe your check valve is not closing, allowing stink from your black take to emanate out of the anti-siphon valve. Grumble :<

Try this...we are gonna rinse the black tank, but before you hook up the hose to the faucet, squirt a good dose of dish washing detergent in the hose, like Dawn liguid, antibacterial is gooder, about a 1/4 cup outta do. Then connect the hose and turn on the faucet and rinse it into your black tank. It'll go thru your valves and maybe -- if you're lucky, unstick whatever is sticking. I do this every time I rinse the tank.

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Old 08-06-2016, 03:18 AM   #16
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Thanks TonyMac. Is this check-valve the same thing as the Air Admittance Valve under my kitchen sink? I don't think it's that. The under sink area where the AAV is smells minty fresh. Is the check valve and AAV 2 separate items? I'll check out that tank rinse you mention though. I've got some Happy Camper coming today as well.


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Old 08-06-2016, 11:01 PM   #17
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The very bottom of air dryer where air expels moisture is called the purge valve and, the brass fitting is called the pop off valve. Yes, you can disassemble and clean purge valve, ( there's actually a rebuild kit) after draining all air; however, that usually turns out to be a temporary fix and, best just to replace dryer and air governor at same time.
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Old 08-07-2016, 09:07 AM   #18
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No, the check valve is in addition to the air admittance, or anit-siphon or backflow preventer valve. The anti-siphon valve is located in the high point of the system, and open to atmosphere thru its "hat" when no pressure is present. This breaks the vacuum necessary for siphon. However, this also allows downstream air from the black tank to flow upstream into the compartment where the anti-siphon valve is located. When pressurized, the anti-siphon valve closes to allow water to flow thru the system. In my system, the flow is upwards thru the anti-siphon valve, and horizontally out of the anit-siphon valve and thru the check valve.

On my rig, immediately downstream of the anti-siphon valve is a 1.5" nipple, which looks like a short section of fitting, which is actually a spring-loaded check valve. Inside this piece is a valve that is normally closed, and opens when presented with about 7 lbs of pressure. It allows flow out of the anti-siphon valve and to the system, but closes when flow is discontinued to prevent poo smell from back-flowing and exiting thru the anti-siphon valve's hat. The check valve alone would stop, but not break the siphon, an anti-siphon valve is required by code in any system that presents a possibility of cross contamination, like a black tank flush system or your home sprinkler system.

On my rig, the anti-siphon valve is a fist-sized brass inverted 'L' shaped device and the check valve is a 1.5" gray plastic nipple coming horizontally out of the inverted L, all located behind the bath vanity drawers for convenience. If you have two right arms, it's very easy to get to.

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