Black Flush Anti-siphon Valve
We’ve chased black tank odors on and off for quite a few years, for the most part they’ve been resolved BUT once in a while we get a slight odor in the fridge/pantry corner of our VL320. Recently I s...
Forum Discussion
I have had other issues with this tank flusher anti-siphon valve (3-way quick-release valve). All the valves may not be the same, but the style I dealt with worked like what BB_TX posted.
I found on two campers that the vent poppet would not seat correctly when the water pressure was applied and blew water into the wall cavity, which was not good...
It appears different brands of tank sprayers address the issue differently. The Camco spinning tank sprayer has a check valve in the head of the sprayer to deal with the black tank backflow. They also supply a water pressure hookup backflow preventer. If you route the tank flusher supply flush hose downhill toward the water connection, it will drain out the unused, clean flush water when the incoming water pressure drops off to prevent freezing in the winter. This method has no valve that vents buried in the wall of the camper and accomplishes tank backflow, draining the excess clean flush water and protecting the incoming water source.
The tank sprayers with a nozzle and no check valve need extras to prevent tank backflow and trapped water in the hose from freezing. For the camper OEM, it may be easier and cheaper to use the tank nozzle with no check valve, install the cheap in wall-mounted backflow prevention to meet a code requirement, and not have to deal with an external backflow prevention valve. I agree this is not a good long-term setup. It works, but when the backflow valve in the wall stops working right, it can create an issue that is not easy to deal with.
I found on two campers that the vent poppet would not seat correctly when the water pressure was applied and blew water into the wall cavity, which was not good...
It appears different brands of tank sprayers address the issue differently. The Camco spinning tank sprayer has a check valve in the head of the sprayer to deal with the black tank backflow. They also supply a water pressure hookup backflow preventer. If you route the tank flusher supply flush hose downhill toward the water connection, it will drain out the unused, clean flush water when the incoming water pressure drops off to prevent freezing in the winter. This method has no valve that vents buried in the wall of the camper and accomplishes tank backflow, draining the excess clean flush water and protecting the incoming water source.
The tank sprayers with a nozzle and no check valve need extras to prevent tank backflow and trapped water in the hose from freezing. For the camper OEM, it may be easier and cheaper to use the tank nozzle with no check valve, install the cheap in wall-mounted backflow prevention to meet a code requirement, and not have to deal with an external backflow prevention valve. I agree this is not a good long-term setup. It works, but when the backflow valve in the wall stops working right, it can create an issue that is not easy to deal with.
