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Monday, October 19, 2009

Funky Furnace

I have a 1992 Damon motorhome. My propane heater has a loud howling during start up. The heater is located under a dinette seat and I find if I pound on the heater cowling over the heater is stops and when it starts up again the same thing happens. I inspected the outside access and can't seem to find anything wrong with the squirrel fans. They are tight. What type of troubleshooting should I conduct to find the problem? I was thinking about removing the cowling over the heater to see if there is something that needs to be tightened. Also my alarms go off when the heater is blowing hot air. It smells like it could be carbon monoxide.
Lee, (Marquette, MI)

Lee, although the howling noise could be caused by vibration, resonance, or a foreign object inside your furnace, the fact that the CO or LP detector is going off and you can smell “gas” is a much more telltale and dangerous sign. This is an indication of incomplete combustion. The howling you are hearing could be the sound of the burner fuel simply not mixing properly with the air, thus causing faulty combustion. In some furnaces, a primary air adjustment can eliminate the howling. Without a brand or model number though, it is impossible to discern if yours is the adjustable type. I’m more concerned about the odor that is emitted. The most common by-products of incomplete combustion are aldehydes (poisonous gasses) and CO, both of which are extremely toxic. Like a howling noise, the incomplete combustion could be caused by the same improper mixture of air and LP in the combustion chamber. A loose or damaged combustion wheel could also contribute to this. It could also be caused by a partial airflow blockage or an incorrectly adjusted or damaged burner component. Whichever the case, it is imperative you have the furnace serviced as soon as possible by a qualified RV service center. They are trained and certified to troubleshoot, repair and service the LP appliances. All LP appliances should be cleaned and serviced at least once a year. There is a set of specific maintenance steps to be performed on each appliance.


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