Best option for composting toilet vent exit

[rmaddy]

My v-nose cargo trailer is about to have a composting toilet installed. It will be all the way up front in the center of the "V". I'm working through the best place to install the vent/fan exit for the toilet. The three obvious choices are:

1. On the ceiling covered with a typical plumbing roof vent
2. On the front wall covered with clam shell cover
3. On the floor[font=Tahoma, Verdana, Arial, sans-serif] covered with clam shell cover[/font]

The ceiling seems like the most obvious but I have a roof fan (MaxxAir) directly above the toilet. Given other constraints, the toilet vent would end up within 6" of the side of the roof fan.  Seems like a bad idea if the roof fan is drawing air into the trailer.

The floor is simple but it doesn't seem ideal to have stinky air venting under the trailer.

The front wall may or may not be best. Given other constraints, the vent would need to be within 12" of the centerline so if the stinky air rises and the roof vent above the toilet is drawing air into the trailer, it may pull in some of the stink (but of course nothing like if the toilet vent was on the ceiling next to the roof fan). I'm also worried about driving with the vent on the front of the trailer. I can position it so it is mostly blocked from the main airflow by the propane tanks on the tongue. But I'm worried the force of air from driving will make the vent airflow blow into the toilet instead of sucking it out.

I'd love to hear from those that have dealt with this. Which option seems best? Thanks

 

[B and C]

You're kinda stuck between a rock and a hard place on that. How about another vent in the back for blowing in and the one on the front always blows out?

IDK how much for fumes comes off a composting toilet as I have a holding tank and a flushing commode. I just turn the fan off when flushing but my vent is about 2 feet away too. I only run my fan blowing in when taking a shower as it is right over the shower and keeps the curtain from sticking to me. I have more airflow control through windows with it blowing out and sucking in air where I am sitting keeping the other windows closed.

 

[tx2sturgis]

Is this a 'powered' vent? I believe most of those heads have a weak 12v fan...just enough to move a trickle of air.

If so, why not add an inline booster fan on a switch, and then run the vent ducting vertically up to the ceiling then make a 90 degree turn, heading rearward, along the interior ceiling next to a wall, maybe behind a cabinet or shelf, whatever, then exit maybe halfway back? 

If it is NOT powered, and you have the trailer closed up and the maxxfan is on exhaust, it will be pulling the exterior air in a reverse flow into the head, so you still have a good possibility for stink there too.

 

[rmaddy]

I do also have a roof fan at the rear of the trailer which is above where the bed will be. I imagine that in most cases I will have the rear fan drawing air in and the front fan above the toilet blowing out for good airflow. The front fan will probably almost always be blowing out to help draw out moisture from the shower and possible bathroom odors, in addition to normal trailer air flow. So maybe this could be a non-issue if the front fan is never drawing air in. But I'd like to allow for such use if needed without worrying about sucking in air coming out of the toilet vent.

The toilet vent does have one of those 12V computer fans at the exit end of the vent hose.

The idea of using a second fan and running a longer hose to exit through the ceiling farther aft might be an option but certainly more work.

 

[Sofisintown]

You can use an individual passive vent to the top. You paint it black, so it is always hotter that the bottom part, and continuously draws air out. At least during day time.
At night you can employ a small 12 volt computer fan.

As for location, anywhere will do EXCEPT for the passenger's side wall of the vehicle, because if you are parked on the curb, it will exhaust poop smells directly to the noses of passerbys.
Not nice!

 

[tx2sturgis]

 because if you are parked on the curb, it will exhaust poop smells directly to the noses of passerbys.

No worries mate, they will all be wearing masks anyway....


:dodgy:

 

[Spaceman Spiff]

I keep being told by composting toilet advocates that there is no smell.

 

[tx2sturgis]

When you do a number 2, there is a smell thru the vent for awhile until things kinda dry out and then of course you need to 'stir' it.

The word 'composting' applies mainly to home base units, but in reality, a mobile separating head (toilet) rarely (if ever) has time to actually 'compost' anything.

It's just separating and holding the occupant's waste products so that they can be disposed of a short time later in the appropriate way.

 

[rmaddy]

I just hooked up the little fan. It's 60mmx60mm and it has a max airflow of 12.7 cfm. I can barely feel the airflow.

I also double checked my measurements. If I do the ceiling mount, the edge of the roof vent for the toilet will be 12" from the corner of the MaxxAir fan.

Given how little air will be coming out of the toilet vent and the fact that the MaxxAir fan above the toilet will mostly be used to draw air out of the trailer, I'm beginning to think that is the best option.

It will be about two weeks before I need to make the final decision and drill a hole so if anyone with experience with a composting toilet in a van/trailer sees a problem with this setup, please let me know.

Thanks everyone.

 

[Ccfree]

Using 1 1/2” Or even 1” pvc run it through the floor and where ever you think best put the fan on the end to draw. I’d do a test on how long a run could pull air.

 

[Sofisintown]

I keep being told by composting toilet advocates that there is no smell.

The advocates will tell you there is no smell because their poop don't stink.
In reality, there is a strong smell of perfume and roses, if that's what you had for dinner last night.