Have a 4 yo Lennox High Efficiency furnace vertical interior install drawing combustion air in through the roof in the combo roof stack vent. Model EL296UH090

Toward the end of the 22 winter it would occasionally throw an error for not igniting on demand. Cycling the power switch fixed it.

Last winter, toward the end of the season it became worse. Would throw an error for open low pressure switch. Replaced the pressure switch and checked the different vacuum lines and limped to the end of the winter. By the end it was not coming on, but I didn't have time to mess with it and decided to wait until now.

Started messing with it when it cooled off a couple weeks ago Replaced the pressure switch again because it kept throwing E223 and E229. While messing around I noticed/realized that the induction motor was never coming on but that it was getting warm. Google suggested there might be debris in there. Since this had now become a personal challenge to my ME background, I plunged ahead and ordered a new induction motor assembly.

Replaced it today. Furnace fired right up upon reassembly. So presumably, that was the main problem. Really easy job, except that they made it hard by the way they installed the gas pipe.

Expected that I would find all kinds of crap down in the old motor, perhaps from an installation issue. But it was perfectly clean. The impellor did seem possibly, slightly "stuck" when I first touched it. But it broke loose easily and spun freely. I cannot say if it possibly had water build up at some point, as it hasn't rained in a month.

Now I am happy I got it fixed, but stumped on exactly what caused it to fail. Somewhat leaning to just a bad part from the factory. I occasionally see new and one year old furnaces where the induction motor is making awful sounds on inspections. But still wonder if there is some installation problem. Mainly, that due tot he vertical installation, the motor housing is the lowest point of the exhaust system, and if water did get into that housing it has nowhere to go. Googling tech forums suggested some installations have a drain fitting at the lowest point. There is even a little nipple that could be for that, but it is not open. I am not comfortable punching holes....


Any thoughts?

No experience with this, but could moisture be condensing in the housing and since it has no where to go, it goes into the motor? Or attacks things in the motor?

Could be that when it turns off (heat stops, motor stops) the pipes are hot but the ambient conditions are cold, allowing the hot gases to condense and build up water in the motor as well?

Is the fan installed in the right way? Like, is it horizontal and should be vertical, or vice-versa? Is there supposed to be a low point in the line (horizontal or vertical runs) that you are missing and now the motor is the low point?

Not sure if you can find official installation manuals, but there should be some on venting/draining of your system from Lennox. Might help out.

~egon

Theoretically, it is installed correctly and is allowed to be installed horizontally or vertically. The exhaust of this type does not have a hood/cap. So between that and the condensation, it has drains designed to handle the moisture. You can see the drain tubes just above the grey flex fitting that connects the motor housing tot he exhaust pipe. The black fitting has a little shelf inside that seems designed to let the water drain to out the two tubes.

My personal theory, is that in the vertical configuration, the moisture drains could be overwhelmed and water would go straight into the motor housing, which does not have a drain. When installed horizontally, the connection of the exhaust and the motor is the lowest point and the pipe to the motor goes horizontal.

I encountered a similar issue where the induction fan would sometimes fail to start. In my case, several of the nuts securing the motor to the fan housing had loosened. This caused the fan to sit off-kilter and rub against the housing. If the fan happened to stop while touching the housing, it wouldn't restart.

Did you keep the old start capacitor and put it on the new motor or did you get a new capacitor with the new motor?

Bought an asbly where everything was new.