Troubled by RV Doc Response

I have trouble with your answer about the check valve on water heaters you addressed in an earlier question. I am sorry, but I have never seen one on the cold water line. The only ones I have seen have been in the hot outlet on the tank. Norman, (Milford, NH)

Norman, you'll find a backflow preventer oftentimes at the cold water inlet, right at the back of the water heater. It's preferred by many of the better manufacturers in order to prevent hot water from migrating back out through the cold inlet. Here's why; If a branch cold line is tee'd into the fresh water system right at the water heater, it could siphon hot water out of the heater and into the cold system. I've seen a few RVs with the water heater located in the lavatory, under a cabinet and in close proximity to the toilet. The customer would get hot water (and steam!) rising from the toilet if he flushed the toilet with hot water in the heater. They thought the cold line to the toilet was plumbed incorrectly but by adding a check valve at the cold inlet, it rectified the "steam in the toilet" issue.

Not all RV manufacturers install a backflow preventer or check valve in the cold inlet because of the added cost and the fact it is not a code requirement, but some do as an added benefit to the end-user. It's a good thing, so let not your heart be troubled any longer!

Travel Trailer Tires

It's time to replace my trailer tires. Installed from the factory are LT235R85/16's. I've been told to get those LT tires off there and replace them with ST tires. If ST rated tires are the best for trailer service, why did the manufacturer use LT rated tires? We have a 34-foot Montana 5th wheel rated at 12,100 pounds. I've heard good and bad about both types of tires. What’s the real story on this question? Leonard, (Kansas City, MO)

Leonard, LT stands for “Light Truck”, ST stands for “Special Trailer.” Although both tires are rated for trailer use, there are distinct differences. For passenger tires (including LT tires), ride, traction, and handling are the key design elements and are all achieved primarily by adding flex to the sidewall. This maximizes tread contact with the road, thus increasing traction and allowing the driver to maintain better control over the vehicle. For trailers, sidewall flexing is not a desired effect because it can be a cause of trailer sway. The stiffer sidewalls and higher operating pressures common with ST tires helps control and reduce the occurrence of trailer sway.

For travel trailers, it is important to match the tires to the application and payload. Since ST tires are constructed with heavier materials, they are tougher and more bruise resistant than typical passenger car tires. This is a plus because trailer suspension systems are generally stiffer and less sophisticated than automotive suspension systems. A tire designed to operate in the more demanding trailer environment will provide you with longer service life and be able to withstand the added abuse trailer tires tend to be subject to.

Bottom line, trailers are more stable and pull better on tires designed specifically for trailer use and I recommend that you switch to the ST type. The manufacturer likely used LT tires because they too are rated for trailer use and are simply cheaper than ST tires.

Non-RV Portable Generator Installation

I have a 25-foot Surveyor travel trailer I also purchased a 3000-watt portable generator. Where would you recommend I mount this generator? On the tongue or on the rear bumper? It weighs about 145 pounds.
Leroy, (Los Angeles, CA)

Personally Leroy, I do not recommend permanently installing portable, non-RV generators. Besides, a portable generator should remain portable. They simply are not suited for a permanent installation in an RV. Certainly do not mount any generator at or near the LP cylinders. The best place for an RV-approved generator is mounted into the side of the coach within a correctly constructed generator compartment. Wish I had better news for you, but electrical integrity and safety are paramount when it comes to generator installations. Installations must comply with the NFPA 1192 RV Standards as well as the NEC.

George Bunzer - Gone, but Not Forgotten

George was a unique character. He was also my Dad. He died eight years ago this month, hence, the reason for this tribute to him. He was almost eighty when he died and if it wasn’t for him, you wouldn’t be reading this, nor would I have a career in RV technical education. He passed down to me much of what he had absorbed through his mobile home industry genes, along with his sense of humor, his view of the world and his fascination with words.

George was a brilliant entrepreneur even before many really understood the meaningful depth of that popular moniker. A self-made man, he revolutionized the mobile home industry in Florida by being one of the first to build strictly custom-made, one-off, modular units, including a two-story mobile home. He employed a cadre of brilliant craftsmen within his business, Geo. J. Bunzer Industries, Inc. I grew up in that environment, spending my summers working for Bunzer Industries while going to junior and senior high school. Himself a gifted craftsman, little did I know that he was exposing me to some of the best craftsmanship in the building trades as well as instilling in me a true, hard-nosed work ethic. During one summer, I’d shadow a master carpenter, the next I’d be connected at the hip to a master plumber, then a master electrician, then a master troubleshooter, then a senior manager, etc., until upon graduation from high school I was well-versed in all the building and repair trades.

After college, marriage, military and another year under his tutelage, my wife and I relocated to Southern California where I began my independent working life at a facility that serviced both mobile homes and recreation vehicles. Through my college studies, as well as my years spent as a US Navy Seabee Military Instructor, and after a few years of master level troubleshooting and repair in various RV shops, I came to embrace the prospect of teaching and began my technical consulting career solely within the RV Industry. But that’s only half the story.

You see George was also a personality of sorts; he wrote many articles along with a monthly mobile home repair column for a small regional publication in Florida. In addition, after relocating to the mountains of Western North Carolina, he ventured into the radio host chair of a local AM radio station with his own, Ask George, daily broadcast featuring repair tips for home owners.

And oh how he loved those Carolina Mountains! Earlier, while still living and working in Florida, we’d visit those mountains every summer for a couple of weeks at an old, revamped, TVA housing project-turned summer vacation resort near Murphy, NC; right in the corner where NC, TN and GA all come together. We rented the same cabin every year so he could have the same convergent view of Hiawassee Lake and the mountains from the same worn sofa in the main room.

Well, after he retired from the mobile home business, George moved with Mom to those mountains permanently. He still wrote his George Sez column every month for that little regional in Florida, but he was also getting a lot of RV-related questions coming in. As I was now firmly entrenched in the RV Industry, working for a rolling stock RV dealership in San Diego, he'd forward those types of questions to me. I’d write the response and he’d publish the Q&A in his column. Eventually, the majority of the questions became RV-related so he suggested to the publisher that I take over the column. And the published, Gary Sez column was born. The year was 1976.

Soon thereafter, we all settled in the Murphy area to enter into a business venture that expanded on yet another of George’s ingenious inventions; the RV Chalet, (he held numerous patents). Though that joint quest lasted only a year, it was successful, once again, in making an impact on the housing industry; the RV Chalet was featured in many articles and books showcasing unique single-family dwellings. (For a detailed explanation about the RV Chalet, go to this page).

In the meantime, back in California, I realized that the Gary Sez column was only featured in that one tiny tabloid publication in Florida. I wondered if it might garner interest in other RV friendly areas as well. This was before the days of media consolidation, when individual publishers still owned their respective geographical magazines. So the Gary Sez column gained additional traction. Within a few months one publisher wondered if he could change the name of the column to RV Doctor. I concurred as yet more publications signed on to the self-published labor of love. The RV Doctor column has now been published somewhere every month for over thirty-three consecutive years. And I have George to thank for that, among other things.

George lived the rest of his life in his beloved NC mountains. He wasn't afraid of dying, but he did have three wishes; he wanted to die at home, without pain, and with his family around him. He was granted all three wishes.

Shortly after he died, I was moved to write a song about him, basically thanking him for all the things he passed down to me over the years. So I gathered some of my musical friends and we booked time at a local recording studio in San Diego. I hope you enjoy this tune about the Old Man From the Hills, my Dad, George Bunzer.

If you enjoyed this song, feel free to download it to your personal mobile device and share it with others. When doing so, please consider placing a small donation below. Thank you!

No Output - RV Generator

I have a Generac gasoline generator in my motorhome. I started it up and it was running fine for about five minutes. Then it stopped putting out any electricity, but the engine is running fine. The 20-amp circuit breaker on the unit had tripped. I reset it and still no output. I have checked both circuit breakers with an ohm meter and I show resistance in the closed position and none in the open position. I checked all the breakers in the coach and they seem fine. Could the problem be further down the line? What is a "J-Box?” Any idea what else I should check? Karle, (Littleton, NC)

Karle, if you are sure the circuit breakers are okay, then there might be something more serious to contend with internal to the generator. First, with the generator running, check for AC voltage at the input to the circuit breakers. This will rule out the breakers and anything downstream. If there is no voltage or lower than normal voltage going into the circuit breakers, then the problem is likely a bad voltage regulator, rotor, or stator on the generator itself. All of these components are very expensive and difficult to replace and they mandate you take the coach to a qualified Generac dealer or service center for repair. 

Also check the voltage at the output of the circuit breaker. If there is voltage at the input to the breaker but not the output, then the breaker is faulty, even though it passed your continuity test. It may break down under current flow and/or higher temperatures. The J-box you referred to is the junction box. It is located fairly close the generator and is the transition connection between the flexible cable coming out of the generator and the conduit going into the coach. If AC voltage is present at the output of the breakers the next place to check is inside the junction box. Remove the cover and inspect and probe the wiring. If there is power there then the problem is further downstream of that. You did not mention whether you have to manually plug your shore power cable into a generator receptacle or whether you have an automatic transfer switch. If you have a transfer switch, that is likely to be the problem if the rest of the areas check out as good.

RV Travel Trailer Tongue Weight

We have a 1996 1/2-ton Chevrolet truck with a 5.7 liter engine and a 3.73 axle ratio. Our owner's manual says we can safely tow 7,500 pounds. We are now towing a 1997 Wilderness travel trailer, (no slideout), and are having no problems whatsoever with towing. Our ride is smooth and we never feel a big strain on the engine. We are thinking about selling our trailer and getting a new Wilderness with a slideout. The UVW on this trailer is about 6,400 pounds, but the hitch weight is substantially higher than with our current trailer. My question is, how important is hitch weight and what happens if your hitch weight is too much for your tow vehicle? I have heard from other RVers that if the hitch weight is too high, your front wheels on your tow vehicle may come off the ground at times and it will be hard/unsafe to drive. What are your opinions on this?
Ellen, (Butler, MD)

Ellen, knowing the correct hitch weight, or "tongue weight" as it is sometimes called, is crucial in order to establish a safe towing configuration with any conventional travel trailer. More prevalent in years past, inadequate tongue or hitch weight was a significant contributor to trailer sway. With today’s engineering standards being more defined, this probable cause from the past has been lessened quite a bit.

Still, in terms of most hitches, the ideal tongue weight should be about 12% of the total weight of the fully loaded trailer. Some of the larger trailers may have tongue weights nearing 17% of the total. Anything less than 12% could have a tendency to be the cause of trailer sway.

If the tongue weight is extremely heavy, such as your fear, the majority of stowed objects may need to be positioned aft of the axles rather than in front of them. In any case, it will be necessary to have your towing configuration properly weighed on a platform scale to determine the optimum positioning of all the stowed gear. All this assumes you are using a weight distributing hitch, by far the most common type of hitch today. As a point of reference, refer to this weight capacity chart:

Class Type Capacity

I Weight Carrying 2,000 GVW

II Weight Carrying 3,500 GVW

II (torsional) Weight Distributing 3,500 GVW

III Weight Carrying 5,000 GVW

III Weight Distributing 10,000 GVW

IV Weight Distributing 10,000 GVW

V Weight Distributing 15,000 GVW

Always mounted to the frame of the tow vehicle, this type of hitch, by its design, distributes the weight to both axles of the tow vehicle. Weight distributing hitches are the preferred method of towing all but the lightest forms of travel trailers. The weight distributing hitch works in concert with tongue weight and all but eliminates your concern of putting too much weight on the rear of the truck. A properly adjusted set of spring bars, in conjunction with a properly sized weight distributing hitch, will shift a portion of the tongue weight to the front axle of the tow vehicle. Your front tires will never leave the ground!

No More PB

I have a fresh water plumbing question. Our motorhome has the grey piping throughout. Recently we replaced the kitchen sink. When I went to Home Depot I was given the newer white type PEX pipe. I already have the crimper and crimp rings. As I made the repair I noticed the new brass fittings were snug in the white pipe but loose in the grey pipe. Continuing with the repair all fittings were crimped. When the water was turned on the grey crimps all leaked. It appears the grey piping is a slight bit larger on the inside. Is the grey piping becoming obsolete? Are there fittings that will convert the grey to the white? Camping World and most places are only carrying the white pipe. Where is the best place to find the grey pipe? Help! Denney, (Lehigh Acres, FL)

Denney, indeed, the older, gray, polybutylene water tubing is no longer available. The white tubing is called cross-linked polyethylene (PEX) and has a different diameter than the older PB. Thankfully there are “transitional” fittings available that will successfully mate the two types of piping together. One company producing them is called Flair-It. They are available at many online retail outlets, as well as most RV accessory stores.

RV Holding Tank Sewer Odors

I recently purchased a 2003 motorhome. I have emptied the black water holding tank and noticed the tank is quite odorous still when driving. I do not notice the odor when the unit is parked. Any suggestions on how to correct this problem will be helpful. Elaine, (Elk Grove, CA)

Elaine, the first thing you should do is fully flush out the holding tanks with copious amounts of fresh water. Keeping them rinsed after each evacuation will help minimize holding tank odors. You only state the tank was evacuated, not if you’re adding fresh water afterward. Also, if you’re not yet doing so, only add enzyme-based tank additives to help break up the solids in the black holding tank. But probably the best thing you can do is to replace the existing sewer vents on the roof with Xtreme Vents. 

I believe I’ve mentioned them before, but it bears repeating. These aerodynamically designed roof vents capture the breeze when the RV is standing still and takes in ram air while driving. Xtreme Vents operate on the venturi principle of air being passed over a tube. As air passes over the open end of the vent pipe, it draws air and odors from the tank. This will help eliminate odors by literally “sucking” them out of the tank. This is extremely helpful, (get it?), especially when a 14-inch roof vent is located very close to the sewer vent. The Xtreme Vent will, thankfully, eliminate that design flaw with some floor plans. And remember, there are just as many odors emanating from the gray holding tank as the black tank. I consider it one of the best add-on components available.

RV slides barely moving

We have just purchased a 2005 coach with three slides, which have rack and pinion electric mechanisms. The large living room slide lifted up awkwardly, went out less than half way and made loud noises. We put it in and tried again and it would only go out half way and made both clunking and clicking noises. The top (of the room) was barely out and the bottom was way out of whack. We tried lubricating it but it seemed to get worse. Now it makes loud clicking noises only and barely moves at all. It sounds like the gears are out of sync. Is there a way of fixing this without waiting and trying to find a repair shop? We are on the road full-time.
Rick, (Westbank, BC)

Sorry to hear that Rick, I wish I could be more encouraging, but unfortunately due to the complexity of slideout mechanisms and room adjustments, I’m at a disadvantage without seeing it with my own eyeballs. Any attempt to adjust slide mechanisms and troubleshoot operational errors should only occur after a complete inspection. And quite frankly, oftentimes repairs cannot be performed in the field. Specialty equipment may be needed in order to effectuate a complete repair. I would, however, suggest you contact a certified mobile RV tech if one is available where you are currently located. There is a chance he might be able to unbind the mechanism, barring any physical problem with broken gears or and issue with the motor itself. Also, the proper troubleshooting strategy depends on the manufacturer of the slideout mechanism; some are proprietary. Perhaps it is nothing more serious than a physical binding or a simple alignment issue. Wish I had more encouraging news, but unfortunately these types of repairs are not usually for the Do-It-Yourselfer.

RV Air Conditioning Question

We have a 2004 Jayco 5th wheel trailer with an air conditioner that cools us and then waits a long time before it starts up again.  We are cooled then hot.  We have asked our local camper sales and service to help, but they say there is nothing they can do.  Do you have any suggestion, or do you think  it just the nature of the beast? Kathleen, (email)

Kathleen, it really depends on the type of thermostat equipped with your air conditioner. I’m assuming you have a roof top air conditioner. Some units have the thermostat located on the interior shroud of the air conditioner itself, while others have a wall thermostat for both heating and cooling. It’s possible either type of thermostat is out of calibration. If you have a wall thermostat, be sure it’s mounted about half way up the wall. If it’s mounted too low, it will take longer for the sensor to pick up the fact it’s getting too warm in the unit.

If the thermostat is located inside the air conditioner ceiling cowling, be sure the sense probe is not contacting any other metal component and that it is clean. Oftentimes, cooking oils or cigarette smoke can coat the tip of the probe, thereby lessening its functionality.

Here’s a picture of the sense probe. (You’ll have to remove the ceiling cowling to locate it). It should be positioned directly in the flow of the return air to the unit and not be touching any other metal component. It should just hang there, sensing the air returning to the air conditioner.

Also, be sure the thermostat is turned all the way to the coldest setting. If the unit indeed eventually cools the coach, the air conditioner itself is probably okay. Some thermostats are also adjustable. And there are additional tests that can be performed before fully condemning the thermostat, but these are better left to the professional RV service technician. Let me know the brand and model number if you need any further assistance, but check the position and cleanliness of the sense probe first and be sure it’s turned to the coldest setting.    

Timely Holding Tank Evacuation

I recently purchased a 2001 Jayco motorhome and the problem I have concerns the amount of time it takes to drain the gray water tank. The black water drains very quickly but when I drain the gray water the bulk of the water drains quickly but it take several minutes (up to 10+) of a steady trickling to drain completely. I've had the tanks flushed and scoped and I've personally inspected the drain valves and they are fine. I've also driven the right front tire up on blocks to help but nothing seems to work. Could you please give me an idea as to what the problem is? This is rather bothersome when others are waiting in line behind me. Carl, (Renton, WA)

Barring any severe blockages inside the holding tank Carl, it is apparent a venting problem exists. As a holding tank drains, air must enter the tank from above. All holding tanks must be vented through the roof of the RV. In some cases, the vent pipe can fall down inside the tank, immersing itself in the contents of the holding tank. This effectively blocks off the vent, thereby eliminating the venting action of allowing air to enter as you try to empty that tank. This is why it seemingly drains normally at first; the weight of water forces the initial gushing. Venting allows air to enter the tank.

Here’s an analogy….place a drinking straw into a glass of water. If you simply lift the straw out of the glass, the water inside the straw drains out as you lift. Now place your finger over the open end of the straw and lift it out. The water remains trapped inside the straw until you remove your finger from the end. Liquid entering the holding tank must displace the air when draining into the tank and air must enter behind the contents during draining of the tank itself. That vent through the roof must work in both directions.

From up on the roof, remove the cover for that holding tank vent. If the ABS piping is not protruding above the roof a couple inches or so, chances are the vent has slipped down into the tank and made contact with the contents. In some cases, you can re-attach it correctly from inside the RV; in other cases, the holding tank must be partially dropped in order to repair that vent connection. A thorough inspection will reveal the best method. The other possibility, albeit slight, is that the manufacturer plumbed the drainage system without the requisite slope; water cannot flow uphill. This may not be your problem since you’ve raised the coach to try it, but it may warrant a closer look.