Review of the German SOG Cassette Toilet Ventilator System

When it comes to today’s RV toilets, getting away from foul odors can be difficult. Even our favorite portable RV toilet, the Thetford C402C cassette toilet, is prone to getting these nasty smells, especially on hot summer days. Indeed, the smell gets worse as the cassette fills up. Sure, deodorizers and other additives help, but eventually the unpleasant odors from the cassette will start encroaching inside your camper. Wouldn’t it be nice if there was a way to eliminate these odors, quickly and efficiently, or prevent them from happening altogether, without the need for tank additives? Fortunately, there is. SOG, a German-based company, produces a number of 12 volt ventilation kits for Thetford and Dometic Cassette Toilets that take care of this problem once and for all.

How the SOG ventilation system works is simple. Each time the dumping mechanism of the cassette toilet is activated, a microswitch activates a small 12 volt fan that extracts the odors from the cassette. The ventilation system not only creates suction at the valve opening, but also draws fresh air in, thereby acting like a seal to prevent any unpleasant odors from rising out of the tank. After each use, the fan switches off automatically, thus conserving battery power in the RV. Better yet, the fresh oxygen brought in by the SOG system not only helps eliminate odors, but also helps with the break down of waste inside the cassette without the need for additives.

Thetford C402C Cassette Toilet

SOG produces ventilation kits for North American Thetford and Dometic Cassette toilets of all models, including the ubiquitious Thetford C402C and C403L bench-style cassette toilets and Thetford C224 swivel-style cassette toilet. Three types of SOG systems are produced to accommodate campers of all makes and models including door, floor, and roof exhaust models. SOG’s product finder will help determine which SOG kit you should buy for your truck camper or van. If you’re thinking about buying this product, we highly recommend that you use the product finder. When in doubt, reach out to the company. SOG’s customer service rep speaks pretty good English.

Each SOG ventilation kit comes complete with everything you need to install the system in your truck camper or van. The installation instructions, written in eight languages, including English, French, and Spanish, comes with plenty of illustrations to make the installation easy. Every SOG kit comes with a small 12 volt fan, a micro switch, a filter housing, a charcoal filter, wiring, hoses, and the hardware needed to install the kit. Basic tools and material will need to be provided by the installer, including basic hand tools, silicone caulking, a power drill, and a 46mm (1.8 inch) hole saw. The typical installation takes about two hours, but will probably take longer as you research the particulars of your camper.

The majority of kits sold by the German-based company aren’t applicable to the North American market, so here are a few pointers to buy the right kit. If your camper has the Thetford C402C cassette toilet with a dedicated flushing tank, you’ll need the SOG II Type D Floor kit, though the SOG Type D Door model will work as well. If your camper has the Thetford C403L bench-style cassette toilet that draws flushing water from your camper’s main holding tank, you’ll need the SOG Type D Door model. If you own a Thetford C224 Swivel Cassette Toilet, SOG recommends going with the SOG Type H Door model. Unlike the Thetford C402C bench-style cassette toilet, this installation looks a lot easier with a lot more room to work with.

Here are a few more pointers. Each SOG installation varies and depends on your model of cassette and your van or camper. Study the instructions carefully and watch as many videos as you can to thoroughly understand the project. Unless you’re dealing with the same make and model of camper and same model of cassette toilet, no two installs will probably be the same. Note also that the positioning of the microswitch, which is attached using VHB tape, is critical in order for the fan to properly operate.

A few notes about those who own the Thetford C402C model. Due to the 20mm depth of the cavities at the bottom of the cassette toilet’s docking station, the ventilation hose will need to be routed and installed below the cassette housing. Fortunately, our camper has a storage compartment directly underneath the cassette toilet where we can route the hose and wiring for the fan and filter assembly. For the SOG Type D Door model, the filter assembly and fan is mounted to a wall or door, while the SOG II Floor model has a large fan and filter assembly with a ventilation tube mounted on the outside with a 90 degree bend.

Why go with the SOG II Floor model rather than the Type D Door model? The SOG II comes with a fan and filter housing/assembly that can be mounted in a wide variety of different locations in your van or camper. In order to avoid condensation from building up in the filter assembly, its best to mount the assembly facing up (as shown in the photo below) rather that on its side. The instructions don’t explicitly state this, but was something that was told to us during the installation. For us, the installation took about three hours. Your installation might take less time or more. Some study of the instructions and planning is needed before you should start the installation.

Closeup of the 46mm hole drilled to pass the SOG ventilation hose assembly.
SOG Fan and Filter Assembly mounted in our BundutecUSA Roadrunner.

SOG was kind enough to send us a SOG Type D Door model and a SOG II Floor model conversion kit to review. Like we said earlier, either kit will work for the Thetford C402C cassette toilet and our camper. For our installation, however, we went with the floor model in order to keep the filter and fan assembly inside (we didn’t want to mount the filter housing on the exterior of our camper that didn’t include the cassette toilet door). For our install, the floor model’s exhaust port is routed underneath the passenger side storage compartment, where it’s practically hidden. As a matter of fact, you can’t even tell we’ve installed the SOG in our camper.

The testimonials of SOG’s Cassette Toilet Ventilator System are outstanding, though the installations can sometimes be a challenge without proper preparation. One Stateside owner of an XPCamper (Nimbl Evolution) installed the system with excellent results using the SOG II Floor model. His installation, which includes, photos was very helpful for our installation. An Australian jury rigged his SOG system by attaching the ventilation hose directly the cassette’s drain cap, which is exactly how the system is designed for swivel cassette toilets using the SOG Type H Floor model. For those with a Thetford C224 Swivel Cassette Toilet, a Winnebago Solis owner posted an excellent video on his SOG Type H Door install.

Installation of the microswitch bracket is accomplished using VHB tape.
SOG Sticker placed over the top vent. The sticker reads, “Technology Replacing Chemistry.”

The Verdict

Even though installing the SOG here in North America can be a challenge, we’ve provided enough pointers in this review to make the installation much easier. Is the SOG Cassette Toilet Ventilation System worth the $350 cost? Absolutely! It has completely eliminated the foul odors we’ve had to deal with in our camper. As a matter of fact, the SOG works so well that tank additives are no longer needed. Sure, you can probably engineer a similar ventilation system for a lot less—if you have the time—but not everybody has that luxury. Most of us are still working for a living and having a professional, plug-and-play system makes things so much better and easier. What would we rate the SOG Casssette Toilet Ventilation System? On a scale of 1 to 5 with 1 being the lowest and five being the highest, we give the SOG Cassette Toilet Ventilation System a 5.

About Mello Mike 889 Articles
Mello Mike is an Arizona native, author, and the founder of Truck Camper Adventure. He's been RV'ing since 2002, is a certified RVIA Level 1 RV Technician, and has restored several Airstream travel trailers. A communications expert and licensed ham radio operator (KK7TCA), he retired from the U.S. Navy in 2004 as a CWO3 after 24 years, holds a BS degree, and now runs Truck Camper Adventure full-time. He also does some RV consulting, repairs, and inspections on the side. He currently rolls in a 4WD Ram 3500 outfitted with a SherpTek truck bed with a Bundutec Roadrunner mounted on top.

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