Holding Tank Odor

[mikedee]

I took an idea from Warren and it worked great. First I emptied and flushed the tanks. Then filled the tanks with water and 1/2 bottle, say 12 oz per tank of PineSol the blue kind and let it set a week or so in each tank.

You will not believe how it cleans the tank.

I also took all the drain vents, I call them island vents, out of the coach. I had four, one under the kitchen sink, under the two vanities, and behind the Headhunter toilet. All four were not working well and a 1-1/2" plastic pipe plug was installed at each location. No issues at all, no slow drains, gurgling or bubbles.

Best of all no smells.

[jello_jeep]

Sorry, been on the road and not up on email/net stuff.

They are vacuum breakers. They cost around four bucks..

Jim,

I also have bench tested the Microphor after rebuilding in my 97 Marathon. The little line that gets a squirt of water each time you flush is sort of a mini P-trap designed into the Microphor and sounds like yours is working as you described.

On my Marathon, there were several plastic valves in various places in the PVC vent pipes that were designed to allow air to be pulled into the pipe. I don't remember what they were called, but if one is bad and stuck open, you will get some stink. I had one under the galley sink and don't remember where the others were located.

Jeep, jump in here, I don't remember the name of the valves!!!

[Jon Wehrenberg]

The industry call the valves air admittance valves They are a check valve that does not let air escape from the system, but does allow air to enter the system through the valve.

As I mentioned before, the role they play is to prevent water going down the drain from siphoning the water from the P trap. If you run a little water from the faucet down the drain it is unlikely you even need the admittance valves and plugging the pipe where they are mounted has no effect on the system.

But if you fill the sink with water, and then pull the drain plug, the resultant flow of water from the sink fills the drain line, and that full pipe will pull the water from the sink AND THE TRAP down into the holding tank. Now the trap is empty and the pipe from the holding tank, through the empty trap is a path for the odors from the tank to reach the inside of the coach.

It is my opinion that using air admittance valves, except in the case of an island sink is the cheap easy way to vent a plumbing system, but it is not the correct way. Most building codes actually forbid the use of air admittance valves except in special cases.