Temperature A-Risin’
Dear RV Doctor:
How do I raise the water temperature on my Precision Temp continuous water heater? I see no adjustable thermostat. The water heater is working, and it’s suitable for a quick shower in the summer, but the water is not hot enough for washing up. I have done the auto/calibrate procedure a number of times, but I would still like hotter water.
David Wyman, Brisbane, Queensland, Australia
Are you certain you need the water temperature hotter than the factory setting of 115 degrees Fahrenheit? That’s fairly hot for a continuous stream. There are several things to check before adjusting the temperature. First, look for flow restrictions in the system. Some showerheads may be equipped with a restrictive device impeding the flow of the water. Also, partially blocked strainers or faucet aerators can affect the temperature of the delivered water flow, so remove and clean all the screens. Look, too, for kinked tubing lines to and from the water heater. If you are mixing hot and cold water at the same time, reduce the flow of the cold water before considering raising the setting of the hot water.
If you must increase the temperature setting, do so carefully and only in slight increments. I probably don’t have to warn you about scalding hot water concerns, but I guess I just did! To raise the temperature setting, remove the access door from outside the unit and pull the electronics drawer assembly out an inch or two to gain access to the circuit board. On the circuit board you will find a small, blue, adjustable pot at the lower right-hand corner. Using a small screwdriver, carefully turn the adjusting screw clockwise to raise the temperature setting. Be sure to move it only an eighth of a turn at a time, checking the water temperature after each adjustment. Electronic components can be damaged by adjusting the pot too far in either direction, so make slight adjustments until you’re satisfied with the temperature.
Batteries A-Chargin’
Dear RV Doctor:
When I install a Xantrex TRUEcharge2 battery charger to my 12-volt-DC battery system, do I have to disconnect the charging side of my existing AC-DC converter?
Tom Jensen, Tacoma, Washington
It’s perfectly okay to leave the stock converter connected and simply wire the TRUEcharge2 in parallel with it. All battery charging really happens as a result of a voltage difference between the charging source and the battery bank. When the charger voltage is higher than the battery’s state of charge voltage, current will flow to the bank. The same concept is at play when there are two charging sources.
If the existing converter in your motorhome is a switch-mode converter, simply wire the TRUEcharge2 in parallel with that stock converter. In other words, connect the positive output of the TRUEcharge2 directly to the positive terminal on the switch-mode converter. The negative output conductor also can be connected to the stock converter’s ground lug. Switch-mode converters produce a relatively clean output, and since the battery acts as a noise filter, a switch-mode converter and the TRUEcharge2 battery charger can work well in tandem. Be sure the charging conductor between the existing converter and the battery bank is of sufficient size for the output of your model TRUEcharge2.
However, if your existing converter is one of the older styles (linear or ferro-resonant), it will be necessary to install an aftermarket diode-type isolator between the two charging sources and the battery bank. It’s the same idea as having an isolator installed between the engine alternator and the two battery systems. An isolator is necessary, since linear and ferro-resonant converters produce a significantly “dirtier” output.
With a switch-mode converter and the TRUEcharge2 wired in parallel, the charging source with the higher voltage output, under the load present at that snapshot in time, will be the dominant charger. For instance, if the converter is producing 14.2 volts DC and the TRUEcharge2 output is 14.4 volts DC, the converter will recognize the 14.4 volts as a higher voltage and will not produce current. However, if the present load is higher than the output of the TRUEcharge2, its voltage will drop (primarily because of lower battery resistance). This is typical of a severely discharged battery, but it will still charge at full amperage. The stock converter will see the lower voltage and produce current to try to bring the voltage differential to zero. Once that level is reached, the TRUEcharge2 will take over to top off the battery bank to 14.4 volts. The switch-mode converter charging output will shut down at 14.2 volts DC.
In essence, the TRUEcharge2 is considered the primary charging source, utilizing its three-stage algorithms as opposed to the single output of the switch-mode converter. Under heavy demand, both the charger and converter will kick in to bring the battery bank up. As the state of charge rises, the converter will conveniently drop off and the TRUEcharge2 will become primary again.
Whatever power is being used by the system (lights, pump, fans, etc.) will emanate from the battery, but the TRUEcharge2 will ramp up its output to match the demand. The TRUEcharge2 can be configured in three ways: as a stand-alone charger, as a multioutput battery charger, and as a paralleled charging source in conjunction with a stock charging converter. It also can be a direct replacement for a faulty stock converter.
Sparks A-Flyin’
Dear RV Doctor:
When I plug the shore power cord into any 120-volt-AC socket using an adapter, or even without the adapter (straight into the 30-amp receptacle), I draw an arc to the terminal prongs. Over time, they have become pitted. Why does this happen? Should I turn off the main circuit breaker before connecting to the power source?
Jim MacLean, Halifax, Nova Scotia
Contrary to what you might think, the bright yellow and green sparks you see when unplugging an extension cord or shore power plug are not electrons zipping around; they are tiny bits of superheated metal burning in the air. Where does that burning metal come from? Well, it comes from the copper contacts on the shore cord when they are plugged or unplugged while the system is energized under a load. This means that every time you plug and unplug the motorhome shore power while the pedestal is powered up, you’re giving up little bits of metal from the contacts, which eventually show up as pits in the surface of the contact prongs.
As this occurs more frequently, these tiny pits tend to spall off more metal, creating even larger pits, and the degradation continues. Eventually, enough metal from the plug contacts will be lost that the prongs will begin to heat up under normal current loads. That’s not a good thing, since they can get hot enough to melt the plastic plugs or even catch fire.
It’s always best to turn off the main circuit breaker on the campsite pedestal before you plug or unplug any shore power or extension cords. Only after you have a secure connection should you turn on the pedestal breaker. Once the plug contacts are pitted, there isn’t much you can do to restore the surface. I do recommend brightening up the contacts, but deep pitting usually mandates a replacement of the entire shore cord.
In order to maintain code compliancy, the male end of the cord must be watertight and molded to the cord itself. Yes, stand-alone 30-amp plug caps are available as replacements. But the mechanical screw-on or clamp-type terminations can fray or become loosened over time. You’ll want to avoid this type of result. Talk about overheating and sparks flying!
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