Odor in the rv

[Mtnquail]

I hate to admit that I have created a problem within our rv. We own a 2017 305RL, Montana High Country, that we purchased in April of 2016. So far our experience has been so positive with this unit. To stop the draft on the floor I covered over the return air vents built into the two steps to the bed bath area. Twice a month I empty the black water tank. I open the drain and start the tank flush and let it empty out . Then I close the black water tank drain valve, keep the flush going, then after 4-5 minutes open the drain and continue rinsing. The label says not to do it this way but the tank is vented at the roof so I don't see the problem. I do this 4-5 times and the discharge then is almost clear so I think it is well rinsed. The problem is we get an odor in the rv after this. When we have been gone for a day or two I will run the furnace without removing the return air vents covering. Yes I read the label, but as I said I believe the tank is vented at the roof. I got up there, pulled the cap off and can see nothing down inside the vent. Hoping others have experienced this and can offer solutions. Thank you for your help.

[DQDick]

The tank may be vented to the roof, but there is no reason to believe that the pipe going up there is glued together. By doing what you are doing you are risking three things that I personally know have happened to others. First you can back up water into the vent pipe and eventually out the roof and all over your rig. Second, you could cause water to leak from an uncemented connection on the vent pipe into the interior walls of your rig and third you could, if the vent pipe becomes clogged with Tp or whatever, cause your tank to split. In short, the label is there because of what's happened to others.

[BB_TX]

By blocking those return vents you are preventing the furnace from recycling air thru the trailer. Since it cannot draw the air from inside the trailer, it must pull it from the basement and any where else it can draw from. Apparently one of those sources is sucking in odors somehow escaping from the black tank or black tank vent. And since the return vents are blocked, all that freshly warmed air is being forced out of the trailer thru what ever openings it can find around seals, reducing the efficiency of the furnace.

[speedster100]

Your cheap plastic vacuum breaker valve is likely the cause of the odors. Replace it with the brass ACME model from Amazon and you should be okay. Usually under the sink in the bathroom.
Other posts on this site with part# etc...

[Dave W]

There are usually 3 vents on the roof, based on our HC with one for the 'attic' for no better term. mYou can smell which is the black tank. You also probably have a Maxxair bathroom vent almost along side of the black tank vent. We have had an occasional odor right after a tank drain and having that ceiling vent open. Also, if you have the fan on and flush the toilet, you can pull odor up. Then there is that Thetford toilet seal that doesn't always close and allows odor in, usually with the fan on but occasionally with it just open. And covering that cold air return ..... As far as the vent valve noted above - they will be on the sink drains to the gray tanks. Of course, as said above, maybe one of those 'skilled' RV builders in Elkhart jsu forgot to use glue on one of the vent lines like he did on our (unused, luckily) washer drain
'