House Calls with the RV Doctor
By Gary Bunzer
Dear RV Doctor:
I have a water heater that seems to be leaking although I cannot actually see it leaking. But I have a towel placed close by the heater and it does get wet. All the water lines seem okay. Can the water heater tank be soldered? Is there any kind of cement to seal the leak once I get the tank out? The water heater is only 2 years old.
RV Doctor: Thomas, you may be seeing the negative effects of electrolysis inside the water heater tank. Electrolysis, sometimes called galvanic corrosion, is quite common in RV water heaters. Whenever water passes through a container, the minerals suspended in the water supply begin to react inside the inner tank of the heater. Even microscopic particles contribute to this natural phenomenon.
Atwood water heaters are glass lined while Suburban’s water heaters are metal but come equipped with a sacrificial anode rod to offset the effects of this electrolysis. When the heater is exposed to higher concentrations of mineral content, the corrosion inside becomes accelerated. This results in tiny pinholes all the way through the tank wall. It does seem odd, though, that your tank would have corroded through in just two years. If your water heater is manufactured by Atwood, the inner tank is replaceable. If you have a Suburban water heater, it is not; a new water heater would be in order.
Be sure to check all the fittings and components attached to the water heater tank before condemning it, however. At the rear of the heater (inside the coach) you’ll find the cold inlet and the hot outlet and perhaps an anode rod. Threaded into the front of the heater will be the pressure and temperature relief valve, drain valve/plug, gas control assembly (pilot models), and, on some models, an anode rod. If your heater has an electric heating element option, that too is threaded into the inner tank. Be sure to physically check each fitting that may be leaking. Leaks at the above-mentioned fittings/components may eventually find their way to the floor area inside the RV. In addition, if you have the motor-aid option, whereby coolant from the engine radiator is passed through the heater to heat the stored water, look at those connections closely. Though they are not actually threaded into the inner tank, they could still leak, causing you to believe the leak is inside the water heater.
Water heater inner tank replacement on an Atwood heater is relatively easy for the handy do-it-yourselfer, though it does mandate a complete removal and disassembly of the heater. Replacing a like-sized Suburban heater is straightforward and, again, easily performed by the handy RVer. Both tasks, however, require the LP-gas line to be disconnected and reinstalled, so be sure you understand the dynamics of checking the coach for LP-gas leaks if you attempt either.
Dear RV Doctor:
I changed my alternator from a 130-amp to a 200-amp model. My battery isolator is only a 160-amp. What is going to happen to the isolator? Will I have to change the isolator? Will it go bad if I don’t change it? It is a Sure Power Model 1602 rated at 160 amps.
RV Doctor: Yes, Jim, it will be necessary to upgrade the isolator to one rated higher than the output of the alternator. It also would be a good idea to check the amperage rating of all the conductors in the charging system as well. While it’s a very good idea “” especially for those I like to call “serious RVers” “” to upgrade to a higher-output alternator, the entire system must be in balance; all parts must be able to carry the additional current. Think of it as the “weakest link” theory. The system is only as strong as its weakest link. You may have a high-output alternator, even a properly sized isolator, but if the conductors or terminals are undersized, they become the weakest link. It’s my policy to have the charging source, in this case the alternator, be the lowest-rated component in the system. All the other components should be sized accordingly to more than carry the entire output current rating. Running with an undersized isolator will eventually burn out one or both of the diodes in the isolator, thereby ceasing any charge current going to that particular battery bank. I’d recommend a 240-amp, dual-battery isolator, using the Schottky-type diodes for your application. For an added measure of safety, you may want to consider adding wire of the same gauge and type as the original wire to parallel the original-equipment wire. This may essentially double the circuit’s carrying capacity.
Probing The Problem
Dear RV Doctor:
I own a 1975 Fleetwood motorhome, and my problem is in how the wires are routed for the fresh water tank probes. The monitor panel does not read accurately for the water tank. The probe is in an upper corner of the tank and is vertical, top to bottom. There are two disconnected wires on the terminal protruding from the top of the probe. Any suggestions?
RV Doctor: Jim, considered “state of the art” in 1975, that vertical probe consists of a square plastic center core outfitted with five metallic rods positioned on the outside of the plastic core. The rods extend vertically into the fresh water container to the individual depths as depicted on the monitor panel. The fifth probe is considered the “common” probe and will be the longest metal rod on the probe assembly; it’s usually located on one corner of the square center core. All five of the metal rods were prone to develop mineral deposits after years of being submerged in the fresh water.
The probe assembly can be removed for cleaning by disconnecting the five wires (or three, in your case) and unscrewing the complete assembly from the fitting on top of the water tank; it’s a simple pipe thread. Clean the rods with a soft bristle brush and perhaps some light steel wool. Be sure to thoroughly rinse the probe assembly with fresh water before reinserting it into the tank.
The routing of the harness throughout the RV can be confusing. It’s quite possible the four individual-level wires are run in parallel with the same levels on the two wastewater holding tanks and are routed to the respective holding tank locations before they terminate at the monitor panel itself. Each of the three tanks has a dedicated common probe, and all three are eventually routed to the monitor panel location. It is nigh impossible to determine exactly how the harness is actually routed inside the RV. It may be possible to run a new five-wire harness from the top of the fresh water tank directly to the monitor panel, or it may be necessary to run the new harness to one of the holding tanks. Each level on each tank will share the same colored wire; in other words, the wire at the 1/4 mark on the fresh water tank will be the same color as the wire at the 1/4 level on the two wastewater holding tanks as well. Simply match up the colors and your monitor panel should indicate the correct level in the fresh water tank. Use wire nuts to connect the wires from the new harness to the probe assembly so you can remove it for cleaning in the future. If the water tank still does not register on the monitor panel, or the two cut wires are too short to splice onto, I would consider upgrading to one of the newer designs of monitoring level indicators, one that is noninvasive and easily installs onto the outside of the containers.