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RV Doctor ColumnRV Doctor #352 Dear RV Doctor, I have a three-burner propane stove in my RV that seems to take longer and longer to perk a pot of coffee. I recently took a trip in a friend's RV and noticed his propane stove perked coffee much faster. On inspection I noticed the flames on his burner were about 1-inch tall and were a nice two-tone blue. On my stove while the flames are blue they are only about 1/2-inch long. Is there something wrong with my burners? My incoming line? The tanks show a constant 150 pounds pressure with no leaks. Are there newer burners that burn hotter? Dan Keller, (Lacey, WA)
Dan, indeed the design of the burner head itself has a lot to do with the structure of the flame emitting from each port, but the BTU rating of each burner is determined by the orifice size at the burner valve itself. The larger the orifice, the more LP is allowed to pass through and into the mixing tube. In today's RV stove top, the mixing of air with the incoming LP is usually non-adjustable, so the only variance in the equation would be the delivery pressure of the LP. It is important to have the delivery line pressure checked annually at the very least. It should measure 11.0-inches of water column which is a very small amount of pressure. 11.0-inches equal four-tenths of one pound per square inch, (.4 PSI)! I'm guessing your LP pressure is lower than normal. That, coupled perhaps with an obstruction at the burner head itself, will result in a much smaller visible flame at the burner head. It's time to have the pressure adjusted or at least checked. Because the LP pressure is relatively slight, it can only be adjusted while monitoring and measuring with a manometer. Never attempt to adjust the pressure without using a manometer. Unless you've had specific training in the use of a manometer, I would suggest you make an appointment at your local RV service facility. It's a quick and easy job to measure and adjust the LP pressure and at the same time, check the entire coach for LP leaks.
Dear RV Doctor, my parents have a 1990 Cobra Class A motorhome with a problem. There is something going on between the alternator and the battery; the battery will not hold a charge. If you use the wipers or headlights or anything like that while driving you lose battery power until the whole thing dies. They have replaced the alternator, the battery and (we believe) the inverter, yet the problem persists. They currently have the whole thing jerry-rigged with a battery charger that is hooked into the generator. Any thoughts on what else could be causing the problem? Kelly Barnes, (Brunswick, OH)
Kelly, battery problems seem to ever nag us. The first step in finding out why batteries seemingly discharge quickly is to analyze the battery itself. Severely sulfated batteries simply will not hold a charge compared to newer, fresher batteries. The degree of sulfation is proportionate to its ability to hold a charge. All batteries self-discharge, but sulfated plates quicken the rate. Find a shop in your area that has a carbon-pile battery load tester. This test will provide insight to the internal happenings of the battery. Clean and tight electrical connections are also extremely important. Corrosive terminals and faulty butt splices and other connections all lead to early capacity loss. Also, determine if the battery has indeed been fully charged. Chances are the battery has not been given a chance to become completely charged. Motorhomes of that vintage are notorious for employing mediocre or even inadequate charging systems, including an undersized alternator. (A fully charged battery is one that, during an independent charging process, maximizes the specific gravity reading and then plateaus. In other words, the specific gravity refuses to rise any higher. After two hours in that state, the battery is then considered fully charged). After the battery has been tested, then focus on the alternator itself. Alternators and convertor/chargers back then did not have the technical algorithms available today for proper and complete automatic battery charging. Tests should also be performed on the individual battery circuits to determine if any drains exist. Some small, parasitic drains are normal, but when current leakages approach 700-800 milli-amps, something needs to be rectified. Obviously, a larger drain on a battery is even worse. A qualified professional RV technician can easily perform this test for you. There is good news, however. Today there are aftermarket alternators and convertor/chargers that increase the RVers ability to extend the electrical life in the batteries. Also, newer battery technology has improved battery performance and has minimized over-charging risks. It should be a consideration for all "serious" RVers of older coaches to upgrade to high-tech batteries, sophisticated three-step chargers and high output automotive alternators. Electrical woes will certainly be minimized and under proper usage, can be completely eliminated.
Dear Gary, I was winterizing my RV and pushed on the check valve in the city fill to let the antifreeze out but the antifreeze kept flowing out. I had to run and turn the pump off. Is the check valve broken now or did it snap out of place? If it is broken, can I just replace the valve? It's a brand new RV! Kim Young, (Mundelien, IL)
Kim, chances are the check valve return spring simply did not allow the valve to seat properly. With the pump turned off, try pushing in and allowing the valve to snap back a couple of times. Use the eraser end of a pencil to push it in fully and then release it quickly. Then turn the pump back on and see if it didn't spring back normally. If it will not seat properly, replace the city water inlet. Of course, you can always simply install a second backflow preventer directly to the outlet of the city water inlet too. I'm a fan of the brass backflow preventer; I would avoid a plastic check valve.
Dear RV Doc, recently I was hooked up to shore power that had issues so I switched over to my generator. At one time the generator powered both roof air conditioners, but now it only runs one at a time, just like when I'm on a regular 30-amp service. Could it be something in the power system? Merle Reitz, (Lemoore, CA)
Merle, I know you are aware, but I want to remind our other readers that your coach was factory-wired for two installed roof air conditioners, but because the shoreline cord is only rated for 30-amps, you are only able to run one roof A/C at a time. Remember each air conditioner must be on its own 20-amp circuit. There should also be a switch inside, (some are automatic, others manual), that allows you choose which air conditioner to run while plugged into shoreline. Running both units off the shoreline, as equipped from the factory, is mathematically and electrically not possible; hence the need for some type of switch. The generator, however, adds another dynamic to the mix. It is rated to power both roof air conditioners at the same time.it has enough output capacity. Typically, the rear air conditioner is hard-wired directly to the generator output. On or near the side of the control box on the generator, you'll find two circuit breakers, one is wired directly to one of the roof A/Cs, and the other breaker is wired to the coach distribution panelboard which protects all the other 120-volt circuits in the coach, including the other A/C. Chances are the circuit breaker on the generator itself is tripped or faulty. And there is the outside chance the air conditioner breaker in the panelboard distribution box is faulty.
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