I replaced the motor on this furnace, hoping the furnace would be back to normal right after the replacement. But, that did not happen. After replacing the motor and reinstalling the fan housing, I flipped the furnace circuit breaker in the circuit breaker panel. Then, since I still had the lower cover panel off, I manually held the switch that is normally held in the run position by the lower cover panel. The inducer motor started running, followed by the igniter/pilot glowing, followed by the burners igniting and heating up the heat exchanger. But, the fan would not start and the furnace eventually shut off, presumably to avoid overheating. After some time, I tried this again. This time, I reached into the fan housing and gave the fan a spin. The fan began running. But, I noticed two abnormal conditions. One was that the fan was running in the opposite direction of the air flow arrow affixed to the fan housing. The other abnormal situation was that the fan kept running, even if I was not pressing the control switch that is normally pressed down by the cover panel. The only way I could get the fan to stop was to cut the power to the furnace. The wires on the new motor were the same colors as the wires on the old motor and I was careful to get the wires on the new motor connected to the right terminals on the control panel. The one exception to this procedure involved two brown wires. On the new motor, one of the brown wires was differentiated from the other by a short black stripe on the wire's insulation. But, the two brown wires on the old motor had no way of visually differentiating, as far as I could tell. So, I had no way of knowing whether these two wires had to be connected to a specific connector or whether the identical color meant that either of these two wires could be connected to either of the terminals. After the discovery that the motor was running in the opposite direction of the arrow, I wondered whether reversing the two brown wires would make the motor run the opposite direction, but I did not try that. So, to reiterate, the motor did not run until I manually stared the fan spinning; And, once the motor started spinning the fan, it kept running regardless of whether the control switch (normally held in On position by the cover panel) was pressed or not. I should add that I heard a humming noise before I got the motor spinning the fan. I have heard, in YouTube videos, that a humming noise may indicate a bad capacitor. And, I've seen a capacitor being replaced in such videos. But, I see no capacitor on this furnace. Do some furnaces not have a capacitor? I'll post a photo tomorrow.

Im almost 60. But with a child's curiosity... or maybe for me, just ignorance : ) ? I've grown up with hot water radiators, then steam radiators for a while then back to hot water radiators. I've always felt the exhaust from the funraces / boilers and same for the gas powered hot water heaters.... that the exhaust was pretty hot and that's why it goes up a brick / lined chimney. My daughter's buying a new house. we were there recently checking out the progress. She has forced hot air heating system. I've heard of using PVC exhausts for newer systems, but hadn't seen one in person. Checking her system... yep, 1 'standard'? white PVC line bringing in outside cold air. And another PVC pipe running out the basement that, when I put my hand on it, was warm. Not even hot. Furnaces these days are THAT efficient!? Is that the same for hot water radiator systems? Is that as neat as I;m thinking it is!? or even older systems exhausts really not that much hotter?