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RV Doctor ColumnRV Doctor #332 Dear RV Doctor, my Wedgewood oven will not light the main oven burner. The pilot light will light, but when the thermostat calls for heat the main gas valve will not open. I'm just not sure if the pilot flame increases in size or if my pilot flame is just not big enough to heat the thermocouple. It seems very small, but if I wiggle the thermostat, it will briefly get bigger. The way it burns on just the pilot position is definitely 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, BC)
Norm, typically after the thermostat calls for heat, here is what happens; assuming the pilot flame is already lit in the oven, when the thermostat is set to any temperature setting the oven pilot should become slightly larger or elongated, (this is also called the extended pilot or high fire), and begins 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 and allows the LP 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 until the main burner actually ignites. Now 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 F. Immediately, the standing pilot should expand and envelope 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 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 if 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 too large that it heats the thermal bulb in the "OFF" position. If the LP 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.
Dear Gary, I have a 1994 Winnebago, gas powered, that I have been living in since the firestorms in this area a while 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 any particular brand or type of battery I should or shouldn't use? Julio Barrios, (El Cajon, CA)
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, in most cases, they are easy to replace. 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 rig and disable the inverter if you have one. Only connect to the 50-amp shore power after all the batteries have been replaced and the conductors attached and terminals 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 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.
Dear RV Doc, we have two air conditioners. The front one seems to work well, while the one in the bedroom seems to cycle on and off once it reaches the set temperature. We can control them separately but it's the one in the bedroom that I would like to have working properly. What do you suggest we do? Can it be the Freon? Denise Filiau, (Templeton, MA)
Denise, you didn't really give me a whole lot to go on, but here are some thoughts to consider. Do you have the same symptoms whether operating the air conditioners off the shoreline connection or with the generator power? It may make a difference. If you only are equipped with a 30-amp shoreline cord, only one A/C can operate at a time. Some RVs are equipped with an additional piece of equipment called an energy management system (EMS) that shuts one off while the other is operating. It may be tied in with each thermostat, depending on the device used to monitor each A/C. This EMS may be malfunctioning. In addition, you may have a faulty circuit board (if so equipped) on the bedroom unit. That unit's thermostat should also be checked for proper operation. This type testing typically is beyond the scope of the average RVer. It's probably best to make an appointment at your local RV service center. If it only happens while running off the generator power, the problem could be solely in the rear A/C unit itself. Typically it's the thermal overload device which fails in this instance. The overload is attached directly to the compressor on the A/C and can be tested for continuity with a Volt-Ohm meter. If the compressor is overworked, due to low refrigerant, etc., then the overload device may trip. It acts like a circuit breaker of sorts and may be fatigued enough to warrant replacement. I'm guessing it will take further investigation to determine the exact cause of your symptoms, but I would recommend you check that overload device first.
Dear RV Doctor, I am interested in receiving some information about the negative effects of ultraviolet rays causing damage to the tires on my RV. Why are RV tires so susceptible to damage from the sun when the tires on my truck don't seem to be affected? What are the facts? Murray Bateman, (Alberta, Calgary)
Murray, the damage caused by ultraviolet (UV) radiation as well as exposure to the ozone virtually affects all tires. RV tires in general are more susceptible to this type of damage since they are considered a slow wearing tire. RV tires typically are not driven as far or as often as regular automobile or truck tires. A symptom of ozone or UV damage is the evidence of cracking or "weather-checking" around the sidewall. Ozone is simply a gas that is in the atmosphere. A mutant of sorts, ozone consists of an extra oxygen molecule which is easily attracted to the oxygen in the air and just as easily attaches itself to other oxygen-related compounds such as water and carbon monoxide. The biggest detriment is that it virtually attacks the rubber in the tires and causes brittleness and a lack of pliability. The big disadvantage - ozone-produced cracks cannot be repaired or restored. The tire must be replaced. One of the ways tire manufacturers combat ozone is by blending ozone resistant rubber compounds during the making of the tire. These special waxes form a protective barrier against the ozone, but in order to be effective, the waxes must be constantly brought to the surface of the tire. During the flexing and moving of a tire while driving, a fresh layer of combative waxes is kept at the surface. Dormant tires on stored vehicles do not receive enough "exercise" to allow the waxes to migrate to the surface and the ozone has a virtual picnic on any exposed area. Ultraviolet light (UV), on the other hand, is produced by the sun and travels in the air as solar radiation. An invisible light, UV is harmful to all rubber, plastics, fiberglass, etc., all of which are common to RVs. The effect of unprotected UV exposure on rubber is similar to that of ozone damage - cracking, discoloration and lack of physical mechanical properties. Like the ozone war, tire makers use a carbon substance to combat the effects of UV radiation. Carbon black is an UV stabilizer that actually absorbs the damaging rays and converts them to a simple heat by-product. The carbon substance will eventually lose its ability to protect against the never-ending assault of the UV rays. Contrary to what some suppliers may say, there is no such thing as a permanent UV protector. Here are a few ideas suggested by virtually every tire manufacturer:
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