Why No Heat?
Dear RV Doctor:
I have a 40-foot 2014 Tiffin Phaeton with two Suburban furnaces. When the outside air temperature falls below 40 degrees, I turn on the furnaces. Initially, both run fine, cycling on and off to maintain the set point. But at about 5:00 a.m., they both quit, and there is no heat or fan. I switch the thermostats off/on, and the furnaces run again for about 20 to 30 minutes, but then they stop again. They run for 20 to 30 minutes each time I turn the thermostat on/off.
Tiffin technicians advised me that the furnaces probably are not the problem, since both turn off at the same time, and that’s too much of a coincidence. So, attention turns to the common elements of both furnaces: the propane tank, the regulator, and the hoses to the appliances. The technicians pointed to these possibilities:
- The ducts or vents might be restricted, and the high-temperature cutoff could be activating.
- The regulator could be bad or the pressure could be adjusted too low.
- The propane tank could have water and/or other contaminants in it. This is the same propane that was in the tank when I took delivery in Florida.
- The ASME propane tank might be one of those Tiffin received from Manchester Tank in which the pickup tube was installed incorrectly.
I took the motorhome to an RV shop that is a Suburban dealer, but technicians could not replicate the problem after running both furnaces for six to seven hours. I think the tank has moisture in it, and the regulator is freezing up when the ambient temperature gets too low — around 30 degrees. Would I be more likely to replicate the problem if I packed the regulator in ice to approximate the early-morning ambient temperature? Can a propane company do a test to determine whether the tank is contaminated? Is there a way for technicians to determine whether the pickup tube was installed improperly? Any help would be very much appreciated.
Mike Tobias
Via Email
Since both furnaces have the identical problem, I agree that the cause isn’t likely to be internal to either furnace. One remote possibility is that the gap spacing at both electrode assemblies is marginal, and when the temperature dips so low, the metallic expansion of the probes steps over that marginal line and renders both units inoperable. The gap between the spark and ground probes should be no more than 1/8-inch; the gap between the ground probe and the flame sense probe should be no more than 1/4-inch. But it would be rare for both furnaces to have this problem at the same time.
I seriously doubt that packing the regulator in ice would work, since the freeze-up problem usually arises from moisture freezing in the internal orifices. It’s not a matter of simply making the regulator colder.
The best remedy for tank contamination is to go to a propane retailer that has the equipment and expertise needed to remove the remaining fuel and any moisture, add a drying agent, and repurge the container to specification. It’s a detailed process that most RV service shops likely will pass on, but a retail gas supplier should be able to do it. I’ve poured out a couple quarts of contaminated water doing this myself.
If moisture is indeed the culprit, it’s quite likely there is contamination inside the regulator as well. As a precaution, I’d replace it after purging the container.
Manchester should be able to determine which tanks were constructed improperly via the serial number or spec number on their data plates. The pickup tube is usually welded in place, since it’s a separate component on an ASME tank.
Another thing that comes to mind is the amount of butane in the blend of fuel. Florida, and the Southeast in general, will likely have a higher concentration of butane in the blend. See whether a higher percentage of propane fuel is available in your area without having to drive too far north.
Also, if possible, you might want to measure the DC voltage at each furnace when they fail. Low voltage also causes ignition issues. Aside from the gas supply, the battery voltage is the only other common connection to both furnaces. This is a tough one!
Why No Rear Exit Door?
Dear RV Doctor:
Is there a reason an emergency exit door is not installed near the rear of a motorhome? I have often seen two doors on a travel trailer but never on a motorhome. I know we have exit windows, but I am elderly and handicapped and know I would never be able to exit through the window. How difficult would it be to install an exit door in the rear bedroom? I would appreciate your help, as I am afraid to travel further without the safety.
Irvin Flinn
Richmond, Virginia
It is a National Fire Protection Association (NFPA) code requirement that all motorhomes have an alternate means of escape other than the main entry door, but emergency windows and roof hatches satisfy that. The code does not insist on a separate entry door, unfortunately.
I empathize with your concern about exiting through the emergency window or roof-mounted escape hatch. In some motorhomes, this may mean a six-foot drop to the ground after exiting. I’ve assisted Mac “the Fire Guy” McCoy (www.macthefireguy.com) with his technique for escaping through the emergency window, and it can be difficult. Mac does have a video on his website that offers instructions for exiting in an emergency.
Years ago, some Type A motorhomes were equipped with a driver’s door in addition to the main entry door on the other side of the coach, but I can’t remember seeing that option in recent years. Of course, all Type C coaches and Type B vans have multiple doors. Earlier this year, American Coach announced that it is offering an optional rear emergency exit door on the American Eagle. The door folds down when released and has a step-down ladder. It is designed for one-time use and costs $2,288. So, perhaps other manufacturers will follow suit.
Many shops can modify an existing coach to accommodate another full-sized entry door; just about anything can be modified. Floor plan design, the routing of electrical wires, the plumbing, etc., may pose a challenge, but in many instances, the addition of another entry door can indeed be accomplished. A few shops I can personally recommend are Truline RV in Spokane, Washington (www.trulinecustomrv.com); Apalachee RV Center in Auburn, Georgia (www.apalacheerv.com); and Classic Coach Works in Lakeland, Florida (www.classiccoachworks.com).
Discolored Plug
Dear RV Doctor:
The June 2015 “House Calls” column (page 20) included an item about a discolored plug. It was unclear from the picture whether the discoloring was on the molded part of the plug or was pitting (typically black) on the plug blade.
If there was pitting, it is due to connecting a load to a live receptacle. If there was discoloration on the plug body, it is most likely because of an overheated connection where the cord wiring is soldered to the plug blade. I have seen this several times; it is a result of the manufacturing process. The overheating of the solder joint also could be caused by a loose connection at one of the RV park receptacles. I saw this once; the neutral wire was not firmly secured to the receptacle, and as a result, my friend lost most of his AC-powered devices.
I make a habit of feeling the plug and plug blades after I disconnect the plug to see whether they are warm.
Bob Lundin, F370218
Loomis, California
You are correct! I also failed to mention another possible cause of that molten rubber portion: The motorhome owner might have plugged in to an incorrectly wired 50-amp receptacle. In a 50-amp receptacle, each hot leg must be on an opposite phase. In cases where the installer simply jumpered over from one hot pin to the other, the neutral conductor can be subjected to well in excess of its 50-amp limitation, thereby overheating that neutral pin and melting the rubber on the plug cap.
There’s an easy check to be sure each hot leg is on an opposing phase. Measure the incoming voltage from hot to hot. If the measurement is 240 volts AC, it is most likely wired correctly. If it measures 0 volts AC, then both hot legs are in phase with each other, and the neutral conductor can be overtaxed to 100 amps.