I have a Tempstar upflow condensing propane furnace. It will light normally, but sometimes during a run cycle, I will hear a pop followed by a wavering/whistling/vibrating/fluttering...very hard to describe, sound. The sound is caused by the gas burning at the orifice with the flame blowing into the manifold tube. The pop at the begining of this is when the orifice lights. The flame at the burner is only slightly smaller than it is normally. Usually, it will correct itself after a period of time. If I blow a gentle puff of air into the air intake of that burner, it returns to normal. This happens mostly to one burner. I have had all 3 burners replaced by local service guy. There is 10" W.C. pressure at the burner valve test port as specified in the manual. What is going on and how do I fix it? Thank You Craig

I have a Comfortmaker RPJ II (believe it is original, from 1995 when my 1340 sqft. condo was built-upper level) paired with a Honeywell RTH230B (a few years old). The thermostat is programmable, currently I have the 4 time slots a day set to the same temperature of 70 degrees Fahrenheit. A few days ago when the problem started, (or when I noticed it) I had the thermostat un-programmed and set to 69 degrees Fahrenheit. We live in Ann Arbor, MI. The last few weeks we have had highs of 14 or so, and the windchill puts it below zero, especially at night. The furnace currently cycles on and off about every 30 secs. While watching it, the blower turns on, the heating elements glows and gas flows and ignites and stays on for a few secs, then everything shuts off. This continually happens for hours while the temperature drops in the condo from the set point of 70 to 65 or so most times and has gone as low as 61. Eventually the furnace kicks on and stays on and heats the condo to around 70-71 and shuts off and resumes its schedule of cycling on and off... Here are a few pictures of the set-up: [IMG]http://i1222.photobucket.com/albums/dd486/Trevor_Labrum/IMG_4456.jpg[/IMG] [IMG]http://i1222.photobucket.com/albums/dd486/Trevor_Labrum/IMG_4457.jpg[/IMG] And here is a video of what is happening, which I believe to be out of the ordinary but am unsure: [video=youtube;2cP_y_eIIWE]http://www.youtube.com/watch?v=2cP_y_eIIWE[/video] This is my first time working with any kind of furnace and I am unsure of what I should be checking, I change the filter about 2 months, and when its changed it never really looks too dirty, but I do it anyway. Any help would be greatly appreciated, I am about to call a HVAC company, but I want to make sure it isn't something stupid before I spend the money. Thanks!