Powered Vent for Thetford Recirculating Toilet - Page 5

**Larryjb** · 12-07-2021, 03:34 PM

I see some of the possibilities you may be considering:

1) plumb the vent down to the main bathroom fan.

Problem pointed out by Bill, sewer gases will come back in unless main fan is running 24/7.

2) plumb vent down through the main bathroom fan.

Problem: You'd have to go beside the fan into the space behind the fan. Rather tricky, involves cutting holes, sewer gases may get back into trailer unless fan is on 24/7, or you can put a baffle on the bathroom fan grate when the main fan is not in use.

3) plumb vent through floor.

Difficulty: drilling a hole through the floor. As long as you don't drill too close to the edge (near the wall), you wouldn't be disturbing any structure.

4) plumb vent through side wall.

Difficulty: drilling a hole through the wall. Actually not hard to do, but you will want a good quality hole saw. If you decide to "undo" it, you can leave the vent cover on the exterior, and put some wall covering over the hole.

Disadvantage: some sewer gas may enter the bathroom window if open.

Venting through drain plumbing vent.

Difficulty: twisting around to get access to the plumbing. The hidden part shouldn't require any maintenance, and can be removed and patched easily in the future, and all the mods are hidden. The advantage is that the vent system can be removed keeping everything looking original except for one small hole near the back of the sink cabinet.

I think the last option is best even if it requires more work because it is the safest structurally and has the least chance of letting sewer gases into the trailer.

That said, I haven't actually done this yet, but given that at least two others have done so quite successfully, I'll likely be going this route.

MrGallegos · 12-09-2021, 09:03 AM

Here is another idea, what about installing something like this?https://www.amazon.com/ScreenLet-Win.../dp/B08N8M3S5G

Then run a pipe or hose from the toilet to the fan, then a flexible hose from the fan out the window port. The flexible hose can be attached to a clamp or notch mounted on the roof to hold the hose (this way the fumes vent above the window). Then when it is time to collapse the TM, the hose can be detached from the fan, rolled up and stored. The pipe or hose from the toilet to the fan can be permanent provided it is not tall enough to get in the way of the walls when collapsed.

**Larryjb** · 12-09-2021, 04:51 PM

Quote:

Originally Posted by MrGallegos

Here is another idea, what about installing something like this?https://www.amazon.com/ScreenLet-Win.../dp/B08N8M3S5G

Then run a pipe or hose from the toilet to the fan, then a flexible hose from the fan out the window port. The flexible hose can be attached to a clamp or notch mounted on the roof to hold the hose (this way the fumes vent above the window). Then when it is time to collapse the TM, the hose can be detached from the fan, rolled up and stored. The pipe or hose from the toilet to the fan can be permanent provided it is not tall enough to get in the way of the walls when collapsed.

I would want to run a hose through the window port so that the outlet can be away from any window. I like the idea though.

**Bill** · 12-09-2021, 09:23 PM

For me, the issue is that you have to cut a hole in the screen mesh to pass the hose or pipe through. And you have to cut the same hole in the ScreenLet thing, overlapping the hole in the screen mesh. Once the cut is made, it may be difficult to keep the cut from spreading under the stress of inserting and retrieving the hose.

Later on, if you want to get rid of the hole, you can remove the ScreenLet easily, but you have to replace the entire piece of screen fabric in that window. I don't think you can do it while the screen is in place in the window. You will need to remove the entire screen, frame and all, and lay it flat on a work surface while you remove the old screen mesh and press the new mesh into the grooves in the frame. This isn't all that hard - all the folks who have made up one of my screen doors have done this, and I haven't heard a single complaint!

Before you start, make sure you can remove the screen half of the window, without dis-assembling the entire window.

Bill

**rickst29** · 12-14-2021, 09:16 AM

As Larry suggested above, and having actually done this, I still think that the original implementation is best. Let me address a few question areas from previous posts:

(1) Going into the existing vent pipe on the exterior side P-trap of the sink prevents any chance of toilet smell coming up in the sink. (The trap, full of waste water, prevents inf-flow of toilet gas.)

(2) Although the long pipe from the toilet's left side level-indicator "cut-out" is prominent, it's length and slight rise combine to assure that liquid will never be drawn into the fan.

(3) The small "computer fan" which I used is VERY quiet. I am not able to tell that it is running, except by noting the position of the power switch. (I used a lighted power switch, presenting a dim blue dot of light when the fan is on.) We turn on the fan 24x7 while camped - the energy consumption is negligible, and the room stays fresh. The aluminum tape which holds the fan in place, between the two PVC adapters from the smaller pipes to the larger fan, may be absorbing some noise in my implementation.

(4) Although the long pipe from the left toilet cut-out could be greatly shortened by swapping the position of the toilet's level indicator, (connecting the vent pipe to the right-side cut-out, very close to the sink), that could introduce some issues in long-term maintenance: The splash-stop valve might not have a lot of room to be friction fit (without glue), and the currently longer end of that pipe (into the under-sink cabinet area) might be more difficult to "pull free" from the fan fitting, for the case of a fan replacement. (per #2, the extra length may also protect from liquid being pulled into the fan.)

(5) with a short length of flex tubing between fan and the vent pipe's new "Y" adapter, both the fan side and the "Y" adapter side are easily maintained, if the flex tubing ever haves a problem.

(6) The existing DWV pipe is already mounted with a rain resistant adapter, and its location does not seem to allow for much backflow of air into an open window.

(7) With continuous airflow from a constant-running fan, the smell of outbound air at the DWV vent is nearly imperceptible (at any distance greater than around 6 inches).
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If I were doing it again, to another TM, I would do exactly the same thing.

swaller8 · 08-06-2022, 11:47 AM

I am in the process of implementing Flyboy's solution. I have the exact parts from your YouTube video and added the ball valve. I am not an electrician and was wondering where you draw power for the fan (diagram maybe)?

Also, did anyone figure out the baffle? If so, what did you use? I will use the ball valve, but a baffle seems a more elegant solution...

Thanks!

**rickst29** · 08-06-2022, 12:05 PM

The switch for the noisy OEM floor fan is on the side of the vanity in my TM. I cut a "T" into it's 12v supply side (always on), to become the supply-side input to an additional switch which I mounted next to the factory switch. The new switch, running the computer fan which drives the stink-o-matic 'powered' DWV, is a tiny lighted one. In camp, it's always turned on.

I was unable to pull and move the level indicator (from the rear right corner to the rear left corner), so my fan intake is a long segment of PVC pipe from a left corner riser pipe, crossing above the motor/switch housing before entering the vanity. I put that pipe in with a moderate rise from beginning to end.

I also added a cheapo-plastic ball valve near the beginning of that horizontal pipe. I close that valve for travel, preventing any possibility of a violent pothole-induced 'splash' traveling the length of pipe (and possible entering the fan).

swaller8 · 08-07-2022, 08:19 AM

rickst29, thanks, I assume I cannot T into the ground as that would have both switches controlling both circuits, right? As I said, am not too familiar with wiring. Where did you run the ground to complete the circuit?

Thanks,

**Bill** · 08-07-2022, 09:01 AM

The existing switch has two wires attached to it. One comes from the 12-volt supply, the other goes to the existing fan. When Rick said he T'ed into the wire on the 12-volt side of the switch, he meant that he connected a new wire to the 12-volt supply wire, not the wire that goes to the existing fan. When you tee into this wire, you are bringing 12-volt supply into the new switch. The other side of the new switch goes to the new fan.

To bring ground to the new fan, you can certainly tee into the existing ground wire, but this is not one of the wires attached to the existing switch. The ground wire is one of the wires attached to the existing fan - the wire that does not come from the existing switch. It is probably connected to a nearby metallic ground, possibly the aluminum skin of the trailer.

Be sure you unplug the TM's big black AC power cord from whatever source you are using, and disconnect the TM battery, before you start any of this.

Ask again if this is not clear. We can provide a simple diagram that ought to help.

Bill

**rickst29** · 08-07-2022, 10:27 AM

Quote:

Originally Posted by swaller8

rickst29, thanks, I assume I cannot T into the ground as that would have both switches controlling both circuits, right? As I said, am not too familiar with wiring. Where did you run the ground to complete the circuit?

Thanks,

My TM is currently closed in the garage, and I can't open it to look - but I did find an suitable OEM pre-existing ground wire nearby. I almost certainly used the ground lead for the 12v toilet flush motor, connecting under the bathroom sink. Also available but less easy to use (because of much further distances) there are many 12v ground wires underneath the sink. The slightly closer propane detector also has one.

With an unlighted switch (which I would recommend) you simply hook the fan ground lead with a jumper into that toilet motor ground wire. (I used a WAGO 3-way connector for that.) With a lighted switch, the switch itself needs a ground wire to run the map within the switch - but the connection being switched is between the always-on 12V power source, and the controlled appliance (being the tiny computer fan).
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IIRC, single-speed computer fans are wired with red=12v, black = ground. Fan plugs with more wires are used with actual computers, where the motherboard uses 3rd and even 4th wires to control and detect fan speed.