House Calls with the RV Doctor
By Gary Bunzer
January 2006
Dear RV Doctor:
I have a 1994 Winnebago, gas-powered, that I have been living in since the firestorms in this area awhile back. Upon checking the batteries, I found they are dry. I’m on a 50-amp shore-power line right now, but I want to replace the batteries, as I will need to move the motorhome soon. Is this a do-it-yourself project or should I have someone come out and change the batteries for me? Also, is there any particular brand or type of battery I should or shouldn’t use?
Julio Barrios
El Cajon, California
RV Doctor: Julio, I can certainly empathize with you; I, too, had to evacuate because of that firestorm. If you are certain the existing batteries are beyond rejuvenation, you’ll need to replace them, which is easy to do in most cases. The first thing you should do is label every wire connected to each battery post. Once you remove all the conductors, it can indeed be confusing trying to remember where each wire was connected, so take the time to literally label each one.
When you are ready to replace the batteries, disconnect the shore power to the coach and disable the inverter if you have one. Do not connect to the 50-amp shore power until all the batteries have been replaced, the conductors have been attached, and the terminals have been tightened. Obviously, use an automotive battery for the engine start circuit. For the house batteries, if you have the room, I recommend four 6-volt golf cart batteries wired in a series/parallel configuration. If you are simply replacing twin 12-volt batteries, go with a name-brand, RV/marine deep-cycle battery.
If you take your time and label each wire correctly to begin with, you should have no problem replacing them yourself. Have them fully charged before installing them.
No Oven Operation
Dear RV Doctor:
My Wedgewood oven will not light the main oven burner. The pilot light will ignite, but when the thermostat calls for heat, the main gas valve will not open. I’m just not sure whether the pilot flame increases in size or whether my pilot flame is just not big enough to heat the thermocouple. It seems very small, but if I wiggle the thermostat, the flame will briefly get bigger. When burning on just the pilot position, the flame definitely is not big enough to reach the burner. I have checked the LP pressure and checked the pilot orifice for blockage. These items are good. Any help would be appreciated.
Norm Geisheimer
Kelowna, British Columbia, Canada
RV Doctor: Norm, after the thermostat calls for heat, here is what typically happens. Assuming the pilot flame is already lit in the oven, when the thermostat is set to the desired temperature, the oven pilot should become slightly larger or elongated (this is also called the extended pilot or high fire) and begin to heat the thermal bulb (it’s not a thermocouple) attached to the safety valve. This thermal bulb, when heated by the extended pilot flame, expands a bellows and opens a pathway in the safety valve. This allows the LP gas to flow from the oven thermostat through the safety valve and on to the main burner, where it is ignited by the pilot flame. That is why there is a time delay when the oven thermostat is first set to a desired temperature before the main burner actually ignites. If there are any blockages in the pilot orifice or its assembly, or if the flame deflection shield is mispositioned, the extended pilot may not fully engulf the thermal bulb of the safety valve.
I’d suggest disassembling and cleaning the pilot assembly once again (some spider nests are quite stubborn!) and making sure the thermal bulb is held securely by the small locking screw or against the stop tab (see photo). Then run the test as explained below, keeping a close eye on the pilot size. It may be necessary to temporarily remove the main burner flame spreader in order to get a clear view of the pilot assembly.
While watching the pilot flame, turn the oven thermostat knob up above 300 degrees Fahrenheit. Immediately, the standing pilot should expand and envelop the thermal bulb portion of the safety valve. If it fails to gain in size, the thermostat is faulty. If it indeed becomes bigger and engulfs the thermal bulb yet the oven main burner fails to ignite, then the safety valve is faulty and needs replacing. The positioning of the thermal bulb in the extended pilot flame mandates that it must be fully in the fire of the extended pilot in order to heat the mercury inside. Also, in some ovens, there is an oven pilot adjustment on the face of the thermostat. If the standing pilot is too small to begin with, the extended pilot might not reach the thermal bulb when the thermostat calls for heat. Remove the thermostat knob and see whether there are any adjustment screws visible through the fascia of the front stove panel. You’ll want the standing pilot flame to be large enough to protrude slightly above the height of the pilot tube, but not so large that it heats the thermal bulb in the “Off” position.
If the LP-gas pressure is at 11 inches water column coming into the range and the pilot orifice is clean and adjusted properly, the thermostat and safety valve should work together to get that main burner lit. The good thing is that by running the above tests, you can pinpoint the faulty component before having to tear the range apart.