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RV UPGRADE – SUPPLEMENTAL ELECTRIC HEAT FOR HOT WATER TANK

The Discovery Owners forum mentioned adding an electric heating element to the propane water heater tank as an economical alternative to always using propane to heat the water. Keeping the water heater running on propane uses the available supply of propane in less than 3 days. Adding an element and running it off of shore power, where most RV parks don’t charge for the amount of electricity you use, makes great sense.

The main problems discussed in the forums, regarding electric heat for the water tank, was the length of time it took to heat the water. Using the electric element alone could take two to three hours for a 10 gallon tank like the one on our rig. Of course the propane could be lit off at the same time and heat the water quicker, but that defeats the reason for adding the electric element.

I found that most retailers of the kits to add an electric element to the RV water heater provided a 400 watt kit for 6 gallon tanks and a 475 watt kit for 10 gallon tanks. But then I happened upon a comment in another RV forum that said they used a “HOTT ROD” conversion that put out 675 watts.

My reaction was that it must be a typographical error, the writer’s mistake, or if it did run at 675 watts it probably dimmed the lights when it was turned on.

Nope.

I found the original “HOTT ROD XP” produced by Diamond Group (http://dg-usa.com/hott-rod/ ) was listed as 675 watts but only 6 amps peak draw. And the 10 gallon kit actually fit either the 6 or 10 gallon Suburban or Atwood RV water heater tanks. So I ordered my kit from RVupgrades.com for $115.50, no tax, free shipping. That’s higher than the 10 gallon conversion kits available online for $99 but those were only 475 and when I inquired whether a 675 watt unit was available that manufacturer said that the highest available on the

market was theirs at 475 watts.

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The HOTT ROD kit arrived and the first thing I verified was the wattage. Yup. 675 watts. And it is made in the USA!

The easy part is installing the electrical element. The kit comes with brass fittings to allow you to screw the element into either a Suburban or Atwood drain hole. And when it comes time to winterize again, you simply pull the rubber coated element end off the element, and then unscrew the element from the drain hole and put it away for the winter. (Be sure the power, and the switch is off and the water has cooled). The kit includes a sleeve to protect the wiring as it passes through a half inch hole that must be drilled in the water heater shield. Be sure to use an extreme corner of the shield and guard against the drill bit diving through the metal for fear you’ll hit the water tank. Supposedly all RV water tanks have rounded sides to facilitate draining so the low point in the compartment shield should give plenty of clearance. It did.

But before I drilled that hole I had to figure out how to get the wires I was going to feed through that hole to a thermostat that I had to tape to the side of the tank. The kits specifically says to NOT use the hack some consumers have used by tie wrapping the thermostat to the hot water temperature relief/overpressure valve. It won’t give accurate temperature sensing and could get in the way of that valve accomplishing its intended purpose.

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On our 2000 Fleetwood Discovery 36T the water tank is in the “basement”. It is not reachable from inside the coach. There is a trap door on the bottom of the basement compartment giving maintenance access to the water supply and discharge lines from the tank to and from the coach.

I wasn’t very happy about the rusted condition of our coach’s basement compartments when

we inspected it. Working with the rusted trap door was maddening. But we knew what we were getting when we bought the rig. For our restricted budget we could get a middle mileage small class A. But we were presented with a deal to trade our travel trailer and a fair investment for an entry level price on a diesel pusher. And the fact our rig had just crossed 102,000 miles when we bought it from the second owner since new told us it was going to show its age.

By drilling a very small hole (that I figured I could caulk closed if it didn’t work) in the water heater panel and sticking a long straightened piece of mechanic’s wire through that hole I found that the path from the water heater panel past the side of the Styrofoam insulation would come out to where I could hook the wires up to the thermostat. After drilling a hole slightly smaller than the recommended one-half inch hole, I used the

mechanic’s wire to fish the wires through from outside the panel to the trap door opening.

I also found that by looking up past the area of the inboard end of the water heater tank I could see the duct work and wiring I had previously viewed in the area below where most coaches have their gas stove. (Ours only has the gas range and the oven is replaced by a microwave/convection oven). I went back inside the coach and dropped

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the wiring end of the power cord for the electric element down the open area past where I opened the trap door for access.

The wiring of the kit is pretty much fool proof. The AC wires had terminal plugs that fit white to white, black to black. Only two wires to hook to the thermostat and each is not only a different color code, but a different size wire butt connector. You cannot put the blue wire on the red terminal. It won’t fit.

The internal circuit breaker on the thermostat is the red button. The temperature setting is on the far right end of this picture. It is set at the factory for approximately 125 degrees.

Although it can be set by the consumer, mine will end up taped to the tank in such a position, at least on our rig, where you’d have to use a mechanics mirror to see the set screw or tear the thermostat off the tank and then have to replace the industrial strength two sided 3M tape that adheres it to the tank. (It really said Industrial Strength 3M on the tape backing before I pulled it off).

I carefully cut away only enough styrofoam insulation for the thermostat to fit, dry tested it, swabbed the tank side with the provided alcohol swab and after waiting a half a minute for the alcohol to evaporate, affixed the thermostat to the tank wall. It felt good and secure. I then placed the plastic partial cover supplied over the terminals. It is primarily to keep metal objects from hitting the terminal screws. It won’t protect the thermostat connections from the elements.

But you can see by the lack of dirt on the Styrofoam insulation that the area inside the water heater tank locker stays pretty dry and clean. I added a piece of heavy duty duct tape from the top of the tank’s Styrofoam cover to the bottom, over the thermostat

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cover, to catch it in place if the manufacturer supplied two sided tape fails to hold it. But I’m pretty sure they supplied the right stuff.

The next step was to route my 120v electric power lines from the RV circuit breaker panel, where I already discovered there was an unoccupied Circuit Breaker position.

My plan was to get 20 amp 120v AC from the CB panel, to a power switch I would mount on the front face of the galley (kitchen) cabinet. The area I chose is recessed under the overhang of the solid Corian counter top and less likely to be brushed against, yet very visible. To make sure we know when it is on, and when it is off, I chose an Industrial quality 20 amp pilot light power switch with a red light in the toggle. When power is applied to the heating element the red light will be lit.

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I verified that my wiring had a clear path outboard of all the heating ducts along the route the Fleetwood factory took to get power to the counter top outlets. I used 12-2 Romex since the line would be carrying a heating element’s load. I realize it is overkill for a supposed 6 amp draw. Perhaps I just didn’t believe the part about only drawing 6 amps and for $4 more in wiring it gives me peace of mind.

I ran the wire from the Circuit Breaker box to an Industrial quality 120v single outlet. I connected the black hot wires together with a wire nut and connected the white neutral wires to the lugs on the sides of the outlet. The ground wire is attached to the ground lug and continues its run to the switch. At the switch I connected the black hot wire to the “line” post on the switch, the white neutral wire to the load post, and the ground

to the ground lug. Since the switch is to be lit when the load is connected I need to add a wire from the load post to the “neutral” post of the switch.

At the single outlet I mounted out of sight within the electrical connection bay under the refrigerator I labeled the outlet to ensure the next owner of our coach understands its purpose. And then I plugged the standard three prong plug from the heating element wiring kit into the outlet.

The outlet provides a positive means for my son and I to physically unplug the wire to ensure the heating element is not powered when it is

removed during winterization of the water heater. When unplugged there is absolutely no way the black power cord can shock someone when it is unplugged from the element prior to removing the element from the tank for tank draining and winterization.

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I completed the circuit by installation of a new circuit breaker in the coach 120v circuit breaker panel. Since I had the option to do so, I chose a circuit breaker that actually contains two separate 20 amp breakers. The left lug was wired to the water heater electric element and that space on the panel list of circuits was marked accordingly. The right circuit remains empty for future expansion and use.

SO, DOES IT WORK?

I left the power on the water heater element for the forty-five minutes it took me to pick up all my tools and clean up the interior of the rig. I felt only a slight warming of the water from the tap.

Since I didn’t cause any smoke or fires during that forty-five minute trial, I left the circuit on overnight and during my day at work. That evening when I returned home after work I checked the water running from the galley sink. It was hot and to see just how hot it was I dipped the galley’s candy/meat thermometer into a bowl of hot water drawn from the faucet. The thermometer immediate read 130 degrees.

I didn’t time how long I ran the faucet at full open before the hot water gave out, but that’s not a functional test of the electric heating element. That’s simply a matter of capacity and we all know we can run out of propane heated water if you stay in the shower long enough.

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Yes. I’d say it works fine. And I can imagine if I were standing at the sink doing the dinner dishes that the little I’d use to hot rinse the washed dishes would stay hot using just the electric element I installed. And so I would highly recommend this upgrade for any RV hot water heater.