[C320-list] Electric head

[Doug Treff]

There were many questions to me about this, some were posted to the list, others were privately sent to me. I'll attempt to answer all of the questions here:

I was trying to create an album on the C320 site and I've been getting upload errors. Those of you who asked me for pictures, I will send them in a private email. I've reached out to Jeff to see why I can't upload.

Before I get into the question and answer, I'll make the following observations: 
- I can go considerably longer between pump-outs because these toilets take much less water to flush than the hand-pump style ones. So you're putting less water in the waste tank with each flush. Dometic says that for flushing liquids, you can get away with a short flush of only 0.3 gallons.

- Toilet odors are almost nonexistent with freshwater flushing.

- I have definitely noticed that we are going through freshwater more quickly - as expected. I've gotten in the habit of topping up the water tanks after every sail if we use the head a lot. It would be quite unpleasant to run out of water and have no means of flushing. I suppose if that happened, you could start dumping buckets of seawater in the bowl and flush that way, but then you'll be introducing the odor problem again. 


1. I bought the following:  Defender item number: 502340HSB-12 which is the Dometic MasterFlush 7120. This model is the oval bowl which is way more comfortable than the standard round marine head. It's really nice to sit on an oval bowl that is the same size as the toilet at home. I also bought the flush switch upgrade kit which is Defender item number 503550. The Dometic guy at the boat show told me it was functionally the same as buying the larger switch panel that had two rocker switches in it, and also less expensive. You can see in my photos that I mounted the switches side-by-side on the curved wall below the sink.

2. The toilet has a rotating bowl that is infinitely adjustable. You just loosen a very large "hose clamp" that goes around the base and the bowl can be oriented in any position. As you can see from the photos, the macerator motor is oriented to the right and the discharge hose comes out the back. Picture 20180903_074149 is a view from the aft side of the toilet base looking forward so you can see how it fits against the curved hull. There is plenty of room to mount the toilet this way. I also took the opportunity to replace all of my discharge hoses. In the rear, I used a very short piece of hose to attach the elbow to the toilet, and then the discharge runs to the right just like my previous toilet. In the same photo, you can kind of see the discharge hose and how I did it. I highly recommend you use some type of lube on the inside of the discharge hoses in case you ever need to disassemble things to replace the joker valve.  If you need more pictures, I can supply them. No spacers or adapters were necessary to get the toilet to fit in this position.

3. The feature that sold me on this model was the excellent reviews online and the rotating base which allowed infinite adjustability in positioning the toilet. I'm very OCD and it always bothered me that the toilet in my boat was not "square" with the back wall of the head compartment.  With this model, I'm able to position it exactly as I wanted.

4. I wouldn't change a thing. Completely happy with my choice, and I would do it all the same again. I did have an issue after about a month where the freshwater solenoid stopped working. I called Dometic for warranty support and they sent out a brand new solenoid free of charge. I was impressed...

Additional things that I think are useful, but you didn't ask...

A. I used the wiring that was already under the head compartment to power the toilet. In my boat, the shower drain sump pump is on the same circuit as the pressure water pump. You can see the switch panel in my photos. I couldn't envision a time when I would be running water, draining the shower, and flushing the toilet simultaneously, so I figured that there was little chance of overloading the circuit. So far I have had no issues with tripping the circuit breaker. As you can see, I used some black wire-loom to conceal the wiring and wire-tied it to the freshwater hose for neatness.

B. In the aft cabin, you can remove the drawers on the wall between the cabin and the head, and then remove the screws in the frame surrounding the drawer compartment. This allows the frame to be removed and gives you good access to the area underneath the head sink for running wires, new hoses, etc.

C. For the water supply, I installed a tee in the cold water line (blue pipes) and connected the freshwater hose to the toilet from there. Luckily, the previous owner had left me with an entire toolbox of plumbing parts, including all of the whale fittings I needed for this project. I also installed a check valve between the toilet and the water supply line to prevent backflow from the toilet into the water system. I used a Shurflo model 340-001 check valve for this purpose. I also installed a 

D. When installing the toilet, it's useful to know that there is a solid piece of wood under the toilet mounting area. All I had to do was drill appropriately sized holes for lag bolts, and my stainless steel lag bolts secured the toilet very nicely. No need to figure out how to get under there to put nuts on the underside. It's VERY solid and feels secure when I sit down on it. The only thing I have left to do (and you'll see in the pictures) is to do a proper repair with Gelcoat and sand smooth to conceal the holes from the old head.


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Doug Treff
doug at treff.us