Extreme Cold and RV Absorption Refrigeration

Will extreme cold (below 5-degrees F.) affect an RV refrigerator? I use my RV all year round and one weekend it was really cold and the refrigerator was not working on 120-volt electricity or LP. Matt, (Calgary, AB, Canada)

Matt, indeed extreme cold can affect the operation of an absorption refrigerator. There are two primary causes of temporary cooling loss. The first is caused by operating the refrigerator off level. I will discount this as being a cause in this case, as it seems too coincidental with the cold weather, but it is worth mentioning. Be sure the unit is operated only when the freezer section is level.

The second is inadequate venting. Often, cold weather, especially in your area, is accompanied by snow which can accumulate on the roof of the RV and blocks the refrigerator vent. You didn’t mention whether you had snow, but if so, the unit will definitely not operate if snow is allowed to accumulate and block the roof vent. Absorption refrigerators operate under extremely tight tolerances especially in relationship to the amount of cooling unit contents. Also the surface area of the fins and the precise amount of heat applied to the boiler is paramount. If any of the insulation around the burner tube is missing or damaged some of the heat can be lost to the colder ambient air and the heat balance will be affected; possibly resulting in not enough heat being applied directly to the generator portion of the boiler.

Inspect the burner tube to make sure the insulation and the shroud are fully intact especially around the area of the 120-volt heating element. Inspect the cooling unit for dirt or other debris that may be affecting the cooling efficiency and wipe or vacuum it clean. Finally, be aware that some internal cooling unit components can reach temperatures up to 20-degrees lower than the fridge compartment temperature. If we assume a box temperature of approximately 30-degrees F., then the evaporator could reach 10 – 15 degrees F. If the outside temperature is 5-degrees F., then ice can form on the evaporator, which can reduce the efficiency enough to prevent proper cooling. If this is the cause, there is no solution and the refrigerator simply will not operate under such severe conditions.

##RVT928

AC to DC Converter Types for RVs

We have a 1986 trailer. We have had a problem with our trailer's electrical and have just discovered that with our battery disconnected and while hooked up to a generator we have no lights, no fridge, nothing that seems to work normally, on the 12-volt system. The fuses all seem fine in the panel. Do you think this could be a converter problem? Barry, (Woodstock, ON)

Could be a converter problem Barry, but it depends on what type of converter you have. Here's one of my RV Facts of Life; not all converters are created equally. Typically there are four types of converter/chargers found in RVs today:
 

* Dual Output

* Single Output Ferroresonant

* Single Output Switching

* Single Output, Multi-stage

The dual output, or split system converter, employs two distinct DC output formats: one for the various DC circuits found in the coach and a single, separate output for the battery connection. Largely for economic reasons, this type converter has been extremely popular among RV manufacturers for many years. Many models incorporate the 120-volt AC breakers within the same cabinet structure as the converter, so all 120-volt AC breakers are located in the same location as the 12-volt DC fuses. Some of the common characteristics of dual output converters include:

            * Less expensive to replace individual components
            * Utilize common parts that are readily obtainable
            * Because of heat, are more prone to component failure
            * A limited charging capability; 5 to 8-amps maximum
            * For large battery banks, charge times may be quite long

The single output ferroresonant design allows for all of its rated output current to be utilized as battery charging current when needed and if the conditions are right. If the branch circuits (lights, water pumps, fans, etc.), are not being used on a 50-amp ferroresonant converter, for instance, then all 50 of the amps will be available for battery charging purposes. Another advantage is that the ferroresonant type will compensate for variances in the AC line voltages. Some ferroresonant converters mandate a battery be connected into the system in order for full output voltage to be obtained. I'm guessing your existing converter is this type.

The disadvantages include poor output voltage regulation. Substantial changes in the output voltage can occur with changes in the output current. In other words, as the RV appliances are used, the output voltage drops significantly resulting in an inappropriate voltage for effective battery charging. And like the dual output converter, charging times can become exasperatingly long.

Because of the heat factor, many ferroresonant converters are equipped with a cooling fan to dissipate the heat generated by the conversion of the voltage. However, all converters are susceptible to heat and, therefore, camping gear and supplies should not be stored in, on or around them. A separate 12-volt DC fuse box or distribution panel is also needed in conjunction with the ferroresonant converter. Characteristics of the ferroresonant converter include:

            * Able to charge the RV battery at full-rated output capacity
            * Contains no SCRs, diodes or PC boards
            * Are more costly for component replacement
            * Higher potential for battery overcharge

Additionally, ferroresonant converters can utilize the battery as an augmentation if any load so requires. For instance, if when powering a 12-volt electric tongue jack on a travel trailer, the load becomes more than the rated capacity of the converter, the current stored in the battery can be utilized and added to the current supplied by the converter. A dual output converter in the same situation would overheat and either trip a breaker or damage other components.

The single output, switching type converter/charger provides a single circuit connected in parallel with the coach battery and the branch circuits. Again, the rated output current can be split between the charging duties and for powering the coach.

Similar to a stand-alone 12-volt power supply, these types of converters/chargers are able to power the coach even without a battery in place. Another advantage of this type is that the output voltage regulation is quite good and some models offer a user-defined fixed output level. This results in a shorter charging time when compared to the dual output type or the ferroresonant type, but mandates strict monitoring of the battery charging procedure in order to avoid overcharging the battery. A little of the "automatic" will be compromised with this type.

The single output, multi-stage converter/charger is by far the most advantageous. Most all sophisticated, multi-stage charging converters include, or offer as an option, a highly developed monitor panel for measuring battery voltage and current flow to and from the battery bank. This is a must for the active RVer or full-timer. They employ state of the art charging criteria developed specifically for deep cycle batteries while optimizing the charging parameters by taking into account the battery temperature, the total amp-hour capacity of the battery bank and the type of electrolyte used.

Most multi-stage charging converters such have an added benefit of a fourth stage, an equalization charge. This breed of charging converter employs the use of microprocessor controlled power MOSFET technology along with PWM for optimum efficiency and performance. This is the one I recommend, especially if you upgrade which is always an option.

But back to your question....first, reconnect the battery (make sure it's fully charged) and see if the 12-volt equipment starts working again after starting the generator. If they do, you probably have a ferroresonant type of converter and there's probably nothing wrong. If the 12-volt lamps, fans and water pump still do not operate, it may be necessary to dig a little deeper.

 

RV Tire Valve Extenders

Enjoyed the show this morning; (speaking about a live Webcast on 1/23/10). One question that keeps coming up and as of yet have not heard a definitive solution. Valve extenders for dual rear tires. I even saw the same question by one of the online viewers so; I know that I am not the only one confused. I know I have to switch to stainless stems but, what type of extender. I've heard pros and cons for woven and solid. I am just stumped. What do you recommend. I've also heard that if you use extenders, you are just adding more places for leaks due to abrasion. See my consternation? Help. Nancy, (San Francisco, CA)

Thanks for tuning in Nancy! I did see that question pop up on my monitor; I just didn't have time to get to it. This question comes up quite often and if you ask three different people, you'll get four different responses!

But I do believe the braided extenders are better than simple rubber. It's good you have the stainless stems; that will minimize the potential for leaks. Though no extender will be totally void of the risk of air leaks, the stainless braided type seem to leak less. Since extenders are almost a mandate for dual rear tires, I'd go with the braided stainless.

Here's what you can do....add a little thread sealant such as Lock-tite to the male threads of the stems before tightening the extender. And give the knurled knob of the extender a little more rotation...not too much, but perhaps 1/8 - 1/4 turn past finger tight. And be sure to check the air pressure quite regularly just to be safe.

 

Antsy RV Antenna

I have trouble with a Winegard crank up TV antenna. It seems to continue to work loose where it travels through the roof of my motorhome. I have had it tightened three times, and the main section replaced once. I still have the problem. Any suggestions?
Gerry, (Henderson, TN)

Gerry, You didn't mention the brand of your motorhome, or the type of roof you have, but many such problems can be caused by insufficient blocking support inside the roof cavity of the RV. There is usually no problem on RVs with a solid roof. With a soft roof, the antenna must be installed next to a rafter for support. In those instances when it is impossible or impractical to do so, insert a piece of 5/8" plywood, 18" x 18" square, between the mounting plate of the antenna and the roof. Have the plywood straddle two adjacent rafters. Secure the plywood to the roof first and be sure to carefully seal against water intrusion. Then, install the antenna to the plywood support piece. This will then distribute the stress of raising and lowering of the antenna to both rafters equally. Also be sure the gears on the antenna are lubed periodically.

In addition, there is a locking nut positioned up inside the mechanism. Since you've had the gearbox already replaced, I doubt this nut has worked loose. You can try reinstalling that nut using some thread lock solution if it has, however. It takes a 15/16" deep socket to remove and tighten that nut. Winegard does have a tool that can also be used if you do not have a deep socket of that size.

Update! From Mike (an interested reader): Regarding your reply to the question on the ever-loosening crank handle on the Winegard crank-up TV antenna; I had the same problem. The malfunction was caused by the end of the spring twisting the crank handle holding nut loose. The factory should have installed a washer between the spring and crank handle nut to prevent the binding. I installed this washer and also installed another washer atop the spring to keep it from eating into the plastic on top. After I did this, the problem was corrected. Additionally, I applied a small amount of petroleum jelly to the washers to reduce the friction. The handle also cranks much smoother now. Hope this helps others!

RV Satellite Set-Up Redux

Dear Readers: In an earlier column, I addressed a question from Mike D. about hooking up Direct TV via a standard cable connection on the RV. Here’s his original question:

Why can you not hook up Direct TV through the standard cable hookup on the RV, and how can you get around this?
Mike, (Idabel, OK)

I must admit I could have worded my original response better as I neglected to broaden the context to include similar situations found in other brands of RVs. I received comments from many sharp-eyed readers taking issue with my original answer, some of whom pointed out the error in my logic. Each of them detailed the method they used to accomplish the goal and every solution was completely different though all were plausible.

There may be an infinite number of specific satellite setups possible in a RV, and with foot planted firmly in mouth, here is a modified response. The main point to remember is that all cable components in the RV must be satellite compatible in order to properly carry the LNB signal from the dish to the receiver. Older RG58 coax cable does not have the capability to carry the LNB signal so if the coach is pre-wired with RG58 cable it will be necessary to either run a new cable to the wall jacks or simply run the cable directly from the dish to the receiver. The cable that is required is RG6 coax, which is satellite compatible and is able to carry the LNB. Additionally, all switch boxes, splitters, and other components must be able to pass the LNB signal from the input to the output. Many passive splitters used in coaches do not have this capability so be sure to check that any non-compatible splitter is replaced or eliminated. Similarly, switch boxes, A/V control modules and even wall jacks need to be satellite ready.

As indicated, there are an infinite number of possibilities in terms of the original installation and the A/V equipment being used. If the satellite system will not function properly due to signal problems the first thing to do in terms of troubleshooting is to run an RG6 cable directly from the dish to the receiver to see if the problem goes away. If it does, further modifications are necessary for a more permanent solution. Thanks to all who responded!

Sky High Electric

I have a Flair motorhome and my electric bill at the RV parks are about three times higher than my neighbors who seem to be using more electrical items. I’m not using the air conditioner and I have a new TV. My refrigerator and converter should be the only things drawing 120-volts AC. All my lights are 12-volt DC. My electric bill runs about $130 a month while my neighbors have bigger rigs plus a wife, which I don’t have. Their usage runs about $35 or $40 per month. My batteries are only two years old. How can I test amp draw on the refrigerator and convertor? John, (Parker, AZ)

John, you’ll need a clamp-on ammeter in order to measure the exact current draw from any electrical appliance while the coach is plugged into 120-volt AC. There is a way to use an in-line meter with an “amperage” scale, but that method means breaking the circuit to the appliance. I wouldn’t recommend that method. There are also aftermarket products such as P3 International's Kill-a-Watt, but devices like theirs are only applicable to 120-volt AC loads equipped with an external cord. It will not work on "hard-wired" appliances, etc.

Another way to calculate current usage is using Ohm’s Law. Ohm’s Law is defined as the way to express the relationship between voltage, current and resistance in any given circuit. They are mathematically relative to one another in the same unique way in each type of circuit. If any two of the three values are known in a circuit, the third can be determined by applying Ohm’s Law.

There are three ways in which to express Ohm’s Law. In text format, Ohm’s Law states that the current equals the voltage divided by the resistance. Also, the voltage equals the current multiplied by the resistance. Or that the resistance equals the voltage divided by the current. Another portion of Ohm’s Law, sometimes referred to as the Power Law, brings wattage into the equation whereby wattage equals the voltage multiplied by the current. You know the voltage is probably close to 120-volts AC so that becomes one of the “knowns.” Most AC devices today will have either the current or wattage rating stamped or printed somewhere on the device or in the user’s guide. I’d begin by calculating how much current (or wattage) your AC devices should be drawing and start there. Factor in how long each appliance is operating and drawing current. Do you get the same result at different campgrounds? If not, there is the possibility of a wiring fault or a metering fault within the campground itself. Sorry, can’t help you with the wife issue.

Washing the RV

I am a new RV enthusiast who recently bought an older motorhome. The coach is in excellent condition but is beginning to show a little oxidation in the paint. I want to do whatever is needed to preserve both the beauty and the value of the coach as far as exterior maintenance is concerned. After receiving much well intended advice from various people, I am in a dilemma as to the best procedure for cleaning the exterior. Is it okay to take it through a truck wash? Or will that be too hard on the window seals, antennas, satellite, etc? Or, is it better to hand wash the coach? Does it need to be hand buffed or just waxed? Are there any special products that absolutely need to be used and also products I should not use? As you can see, I want to do what is best, but just don't know which way to go. I'm really most concerned with the truck wash. That would be really easy but it just seems to me that it can't be good. Vicki, (Paducah, KY)

Vicki, it would be fine to consider a truck wash center to clean the motorhome as long as you skip the "pre-rinse." According to reports I've read, the US and several other countries are working to halt the use of HF or ABF (Acid) "pre-rinse" products. So if you are asked about a “pre-rinse,” decline it.

Which is better, hand or line wash? Though a line wash is done by someone else, (and saves you the elbow grease), I personally favor hand washing. It puts you face-to-face with the finish of the coach and allows you to actually see the things that require your attention before they become a major issue. Frankly, it is your coach and the reality is you will do a far better job than any line wash employee. This is especially true if you invest in some good quality brushes. There are many available but typically the softer the brush, the easier it will be on the finish of the rig. You asked about buffing or waxing and what products to use and/or avoid. I think it’s better I share my philosophy with you concerning exterior RV care maintenance procedures.

Start with a monthly sweep of the roof to help minimize dust, pollution and chalk buildup. This will also help to eliminate those dreaded black streaks. Use a soft-bristle broom and a dustpan to remove the accumulation from the roof. If the roof is fiberglass or painted aluminum consider waxing it. If the roof is rubber or vinyl, treat it only with products designed to leave a dry finish. Waxing or treating will minimize the amount of dust and dirt that sticks making future sweeping and regular care easier.

Wash and wax the coach regularly; I recommend once every three to four months for the best, longer-lasting results. Make the task easier by working only one side each month, then the front and rear in succeeding months. Using this schedule will reduce your time at the task making the overall process more manageable. Product selection can be critical so I suggest sticking with brand names from within the RV marketplace. Become very familiar with your vehicle and its many surfaces prior to making your selections. Know the make-up of every exterior surface on your rig. Most products will list acceptable surface applications so always read the label carefully. Be sure to read and understand the directions (so many of us do not).

If you have a question about any product, call the supplier directly. Have them convince you why you should be using their product. Company contact information is usually found on the product label. Most suppliers will have toll free help lines and many have web-sites that can be helpful. Look for a UPC bar code on the label. Bar codes are an indication of the manufacturer’s commitment to the retail marketplace.

Avoid homebrews and so-called backyard chemistry products; they rarely work and may even cause surface damage. Avoid any product that does not list a phone number, address and UPC code on the container. The good ones are proud of their product and will always welcome feedback and communication. Once a product is selected be sure to choose a small inconspicuous area on the coach to test it first. Evaluate it for a few weeks or longer if necessary. This will keep missteps manageable and you’ll find the best product match. If the result of testing is acceptable, complete the coach and maintain it regularly. Lastly, consider a total coach cover for those brief periods of non-use. Avoiding UV and ozone damage is very beneficial.

Broken Anode

When trying to remove the anode rod from a water heater the plug and about two inches of the anode came out but the rest of the anode remained wedged in the opening. There isn't room to grab onto the piece that's left. Is it advisable to just tap the remaining portion into the tank? Advice would be appreciated.
Larry, (Santa Barbara, CA)

Larry, I see no harm in simply tapping it back into the tank. It’s totally submerged when the heater is filled with water any way. The only problem may occur when you annually drain and flush the water heater. (You are doing that, correct?). It’s possible for it to slip into the opening while draining. Just be sure to check the new anode every year, but there should be no accelerated deterioration of the new rod with the older one sitting on the bottom of the tank. If the water quality is substantially reduced in the coming years, perhaps then I would replace the entire water heater or the inner tank. Oh, don’t forget you’ll need a new pipe plug now