Furnace Inefficiency
Dear RV Doctor:
I have an older motorhome with two sideways-mounted propane tanks in the compartment. My furnace was working fine until one of my propane tanks ran out and I turned the other one on. Must both tanks be turned on at the same time for the furnace to heat properly? The furnace is putting out only slightly warm air now. Please help!
Diana Dalton, Covington, Kentucky
Both propane cylinders do not need to be opened in order for the furnace to operate properly. However, most RVers take advantage of the regulator’s automatic changeover feature so that when one container is empty, it will automatically switch to the other tank with no loss of propane delivery. Both cylinder valves do have to be opened for that.
In your case, all propane flow stopped when the first container was empty. In between the time when you noticed the empty container and opened the other container, air must have gotten into the system somehow. You could try lighting a couple of stove burners to eliminate any air from within the closed system. Once the flames on the stove are burning with a nice blue color, try initiating the furnace sequence again. If it ignites, burns, and heats normally at that point, you’re good to go for those chilly nights. However, I would strongly suggest that you have a professional RV service technician perform some diagnostics on the complete system (including all the appliances). The propane regulator should be tested and adjusted to the proper outlet pressure; the entire system should be checked for leaks; and it probably will be necessary to inspect, clean, and service the furnace if those procedures have not been performed in the past year or two. For optimum performance, all four of the propane-burning appliances (furnace, stove, refrigerator, and water heater) should be cleaned and serviced annually.
Interchangeable Fan Relays
Dear RV Doctor:
While recently working on my Atwood 8535 furnace, I found that the blower relay was bad. The RV supply store wants to sell me a new circuit board, saying that the relays I need have been discontinued. According to my sources, Suburban still makes the blower relay. Are Atwood and Suburban relays interchangeable? Why replace a circuit board for $150 when it only needs a $30 relay, right?
James Kennedy, Jacksonville, North Carolina
Under normal circumstances, I would recommend replacing Atwood components only with Atwood components, and vice versa. In other words, keep all parts from the same family. However, in the case of printed circuit controls and a few other components, many supplier manufacturers utilize the same sources. In your case, the fan relays are identical, so it is permissible to install the Suburban relay in the Atwood furnace and save the difference in cost. Just to be sure, I verified this information with my contact at Atwood. Good troubleshooting there, James.
Nonfunctioning Converter
Dear RV Doctor:
I just finished remodeling the interior of our 1989 Coachmen Catalina Type A motorhome on a P-30 Chevrolet chassis. Since then, none of the 12-volt-DC components will operate off of the coach batteries. All systems — lights, water pump, water heater, refrigerator, etc. — work when plugged in to shore power or when powered by the generator. The battery disconnect panel is lit when plugged in (both lights), but it doesn’t activate or light up when not plugged into 120-volt AC. The battery disconnect system doesn’t seem to be functioning either.
I don’t know whether to replace the panel, one or both relays, or if there is something else I should check. Could I have disturbed the wires on the relays somehow? I did replace the one relay located by the engine compartment battery, but I thought I swapped each wire one at a time in order to get it right. Is there a schematic for this system (Intellitec DB2), or am I in left field?
Dave Browning, Escalon, California
I sounds as though the switching relay inside the converter/battery charger is not releasing and moving back to the battery position when 120-volt-AC electric is removed. A common problem with some older converters is that they are prone to sticking. I’m not sure which converter is in your motorhome, but that’s where I would begin the diagnostic testing. I’m assuming the battery bank itself is healthy and charged. My RV Owner’s Handbook includes a complete section on troubleshooting the converter/battery charger.
In all honesty, it’s probably not worth the expense to have the converter repaired if it is faulty. Battery charging technology has changed dramatically over the years, and thankfully for the better. Since you’ve gone to the extent of remodeling the motorhome, I’d suggest upgrading the converter/battery charger to a newer, three-stage charger. As far as finding more information about Intellitec disconnect relays, or any Intellitec product for that matter, service manuals are available online at www.intellitec.com/techsupp2.htm. If you are determined to have the old converter repaired if it is found to be faulty, you can contact Mark at M&M Electronics (www.mmelectronicrepair.com, 888-849-1615). This is one of the few shops I know of that repair older RV electronic devices.{loadpositionEndBlurbHouseCalls}