RV Doctor Column RV Doctor #280 Dear RV Doctor, We have a 34-foot Pace Arrow motorhome. The fuel supply hose from the fuel tank to my generator has deteriorated to the point where the generator will no longer operate satisfactorily because of air leaks in the hose. The way I see it, I have about three options and am requesting inputs from others that may have faced the same situation. Option 1 - Drop the main fuel tank in order to install a new fuel line. In my opinion, this would be very labor intensive, a nasty job and the least desirable option. Option 2 - Install an auxiliary tank someplace either under the chassis behind main fuel tank or in one of the side storage bins. Option 3 - Install a "T" in the fuel line going to the main engine on the suction side of the main engine electric fuel pump, which is located alongside the fuel tank, then run a new hose from the "T" over to the inlet to the fuel pump on the generator. This would be very easy to do as everything is out in the open and easily accessible. This is my favorite option. The only downside that I can see to this option is the loss of the protection against running the main fuel tank empty with the generator. I would appreciate any and all thoughts and ideas. William Hamlin, (Wappingers Falls, NY) William, I have always recommended your option #1. Dropping that tank is much easier than installing another tank just for the generator. Strict laws and very specific requirements, by the way, govern such installations and not many RV repair facilities are equipped or licensed to perform that service. Option #3 is not a viable option either; you risk the chance of starving the motorhome engine for fuel in some situations when running the generator while driving down the road. Granted, not often is this done, but it could be a factor as this would over-work the respective fuel pumps. They would be competing with each other for each ounce of gasoline. Plus, as you state, there is still the risk of emptying the tank via the generator and possibly leaving you stranded in the boondocks. Dropping the tank to gain access to the draw tube connection at the top of the tank is really not that difficult. You do need a floor jack, some safety jack-stands and a nearly empty tank of fuel. Remove the fill assembly at the side of the motorhome so the fill hose and vent hose will follow the tank to the lowered position. Place a two-foot square piece of plywood on top of the floor jack positioned under the center of the tank. This will help distribute the weight of the tank on top of the jack. Apply light pressure to the bottom of the tank to support it. Remove the installation straps fully, or bend them out of the way. Position the safety jack-stands at each end of the tank in case the floor jack looses hydraulic pressure. Slowly lower the tank, keeping an eye on all hoses and wires, etc. Remember, you do not need to completely remove the tank, just lower it enough to gain access to the hoses on the top. Professional Hint: Replace ALL the hoses since you have gone to this much trouble! Including vent lines and vapor return hoses, etc. Be sure to tighten all clamps securely. Raise the tank back into place with the floor jack and reattach the mounting hardware. Finish running the hoses to their destinations and you're done. Dear RV Doc, I remember attending one of your seminars about batteries so of course my question is on batteries. I cannot put my hand on the booklet you provided from the seminar, but I've got two 6-volt golf cart batteries in my motorhome. Each has a label that reads 107 minutes. What does that actually mean and how does that translate to an Amp-Hour capacity? I remember you saying that connecting two 6-volt batteries in series doubles the voltage, (to 12 volts), but the current remains the same. Is that correct? Thanks! Dan Finch, (York, PA) Dan, Batteries today are rated or compared using four different methods: reserve capacity, (RC), ampere-hours, (AH), cold cranking amps, (CCA) and a little known method called life cycles. Though an older method, the AH designation is still used for some deep cycle batteries. It measures the amount of current a battery can deliver over a period of twenty hours. Since some Group 27 deep cycle batteries can deliver a constant current of about 5.25 amps over those twenty hours, many are said to be 105 AH batteries, (5.25 times 20). Cold Cranking Amps, (CCA), is used primarily for engine starting batteries and takes into consideration the ability to provide current in cold climates. The colder the temperature, the less the battery is able to provide the rated current. The standard for this method of rating measures the amount of current a battery can deliver for thirty seconds while keeping the battery voltage at a minimum of 7.2 volts. As an example, an automotive battery rated at 650 CCA means that battery can provide 650 amps for a continuous thirty seconds and keep the voltage over 7.2 volts. Looking at a battery's total life cycles is a relatively new method of rating batteries. It is especially useful when comparing gel-type batteries or AGM batteries. It is the number of times a given battery can be discharged to a certain level then recharged to full capacity. Some AGM batteries, for example, can be reduced to the 50% level and recharged about 1,000 times, or life cycles. Reserve Capacity is what you see on the label of your batteries. RC is measured in minutes and denotes the number of minutes a battery can deliver a constant current and maintain a voltage of at least 10.5 volts. Yours evidently is designed to provide a rated current for a total of 107 minutes and keep the voltage at or above 10.5 volts. To determine the AH rating of any battery, multiply the RC by a factor of 0.65. The factor of 0.65 times the RC of 107 reveals each of your batteries is rated at 70 AH. Indeed in a series configuration the battery voltages are added together, but the capacity to store the current remains the same. Dear Gary, My 20' Prowler has a five year old propane water heater that explodes and blows out the pilot on gas ignition. It shuts down without heating the water. The venting is good and the thermocouple tests Okay. This is a fairly recent problem. The unit has On/Off/Pilot knob and an adjustable screw. What does this screw control? Richard Whipple, (South Bend, WA) Richard, It's my guess your water heater is in need of a good cleaning and servicing. A professional "clean & service" includes verifying the LP delivery pressure to the water heater and checking the cleanliness and alignment of the orifices and the mixing tube. The adjustable screw you see is the pilot adjusting point. This simply adjusts the size of the pilot flame. The optimum position and size of the pilot flame is when the flame encompasses no more than 3/8" of the tip of the thermocouple. In this case, bigger is not always better. If the LP pressure is 11.0 inches of water column, (this mandates the use of an accurate manometer), and the main orifice, the pilot orifice and the curved mixing tube is clean, the last adjustment to check is the primary air intake. Open or close this sliding adjustment on the mixing tube so that the main burner is colored mostly blue and the roaring of the burner is only heard within five feet of the unit with the door closed. If the flame is too orange or if soot is visible emitting from the exhaust, or if the flame burns back into the mixing tube during a heating cycle, a more definitive adjustment will be necessary. Keep in mind all LP appliances need periodic cleaning and servicing; more so after periods of non-use when critters have had a chance to nest in or near the orifices and mixing tube. A regular annual checkup will keep your appliances humming along and eliminate unnecessary downtime during your travels.
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