DaveOglevie Report post Posted October 18, 2011 I recently acquired a used 31-foot 1995 Rexhall Aerbus with 79K miles). I have since spent several thousands of dollars (deferred maintenance). New radiator, tires, shocks, full tuneup, all fluids flushed and refilled, awning, window seals, and many more small items that we have fixed and forgotten. What I haven't gotten done are two things. Our furnace doesn't ignite and I have to manually have to light our hot water heater. These are both luxury items, since our last RV was a small Toyota-based Itasca. Do any of you reading this have any wisdom that you might care to share about finicky furnaces or how to get our water heater to self ignite? Thanks, Dave Share this post Link to post Share on other sites
shields Report post Posted October 18, 2011 Hi Dave, If you could provide further details, it might help us assist in troubleshooting with you. As to the hot water heater, the unit sounds operational since you are manually igniting it. So, let's assume the trouble is the automatic ignition. What model is the unit? When you attempt to turn it on automatically, to you hear any clicking noises (trying to spark)? Is the unit getting adequate power? How to the electrical connections look? On the furnace, the same questions seem pertinent. Also, do you have the same trouble when connected to shore power or with the genset running? Does the furnace thermostat control other devices (a/c units, or a fan)? If so, are those units working properly from the thermostat controller? If you could offer some further details, we can probably help you get to the bottom of these troubles. Good luck, Tim Share this post Link to post Share on other sites
DaveOglevie Report post Posted October 19, 2011 Tim, Thank you for your response and questions. Regarding the water heater (a Suburban SW6D), my spousal unit said she heard what sounded like a valve unit turning on while standing in the kitchen but I heard nothing while standing next to the exterior access panel. I saw no spark on the ignitor. I removed the ignitor and cleaned the electrodes. I regapped the electrode to 1/8".Still no spark even though we cycled thru several times. I did get the water heater to light by putting a butane flame next to the non-working ignitor. All of this was done while plugged into AC power (the generator is yet another project). The furnace is on a shared thermostat with a Magic Fan, and may tied to a second thermostat in the bedroom that controls the two air conditioners. I hadn't thought of the second thermostat until you asked so now I have yet another variable to test. Thank you for pointing it out. I haven't had a chance to try the A/C's as I don't have access to a 30 amp power supply. Best Wishes, Dave Share this post Link to post Share on other sites
shields Report post Posted October 19, 2011 Hi Dave, On the hot water heater, it sounds like the igniter isn't operating; i.e. sparking. Three prospects come to mind: (1) no power is getting to the unit, (2) the igniter unit is inoperative, or (3) grounding/corrosion troubles. Given the age of your coach, all three are possibilities. Testing the ground side is easy. Run a separate 12V power to a test lamp and then try to ground the light through the ground side of the igniter circuit. No light = bad ground. Similarly, testing the supply side of the circuit is simple. Connect a test lamp to the supply side, ground to a known/solid ground, and activate the circuit. No light = no power. If both the power supply side and the ground side check out ok, install a replacement igniter unit. As to the furnace, it would seem strange to have it controlled by the Magic Fan. The thermostat on the Magic Fan more likely sets the termperature at which the fan activates in the "automatic" mode. Are you sure the furnace isn't controlled by the second/bedroom thermostat ? Please check your controls and manuals and we should be able to figure that out. Good luck, let us know how things progress. Tim Share this post Link to post Share on other sites
DaveOglevie Report post Posted October 21, 2011 Tim, Thank your for your guidance. I ran the ignition tests on the hot water system that you suggested and have found that I do have a secure ground but that I don't have power to the ignitior. Please remember that I was able to ignite the flame with my butane lighter so the fuel is there. What is the next step I should take to try to fix the sparking device?. Parts are not immediately available as I live in a small burg? As to the furnace, yep you were correct. The heat system is controlled by the bedroom thermostat. These larger rigs are still a mystery to me. My last rig was a 21' Toyota Class C (Toybox) so I'm not used to having more than one thermostat. About the furnace, now that I have found the real control I have found that the furnace makes all of the proper responses, turns on the fans but it won't ignite the propane. Your thoughts? Dave Chelan, WA Share this post Link to post Share on other sites
DaveOglevie Report post Posted October 21, 2011 Tim, Thank your for your guidance. I ran the ignition tests on the hot water system that you suggested and have found that I do have a secure ground but that I don't have power to the ignitior. Please remember that I was able to ignite the flame with my butane lighter so the fuel is there. What is the next step I should take to try to fix the sparking device?. Parts are not immediately available as I live in a small burg? As to the furnace, yep you were correct. The heat system is controlled by the bedroom thermostat. These larger rigs are still a mystery to me. My last rig was a 21' Toyota Class C (Toybox) so I'm not used to having more than one thermostat. About the furnace, now that I have found the real control I have found that the furnace makes all of the proper responses, turns on the fans but it won't ignite the propane. Your thoughts? Dave Chelan, WA Share this post Link to post Share on other sites
shields Report post Posted October 24, 2011 Hmmmm, We have two propane appliances with the same trouble; i.e. both appear operative but will not ignite. I'm wondering if there might be a common cause. Many of these systems won't operate properly below 11 volts DC and you mentioned the genset is not working. Is there any chance you could get the unit plugged in to 120 VAC, or bring a portable generator to power the unit while you test this idea. It seems worthwhile to try this out before tearing into the igniters and wiring. Is your refrigerator igniting ok? If not, then I would be even more suspicious of low voltage as the culprit. Let's try to get the coach plugged in to 120 (either shore power or a genset) and see if the igniters fire up. If so, you're all done. If not, it will be time to dive into the wiring and the igniters. Let's hope it's the voltage. Tim Share this post Link to post Share on other sites
wolfe10 Report post Posted October 24, 2011 Excellent advice, Tim. Use a digital voltmeter (starting under $10 at Radio Shack, Sears, etc) and check voltage at the battery and also at each appliance that is not properly functioning. Fully charged 12 volt battery at rest= 12.7 VDC. 50% discharged= 12.2 VDC. If below 50% recharge the battery before continuing with your troubleshooting. Share this post Link to post Share on other sites
