So it is snowing in here, in Portland. An event quite popular since it does not happen often and everybody gets an excuse to stay home couple days. The temperatures are dropping, the furnace is running and I remember that I’ve not changed the air filters. So I go, do that, turn the heat back on and … there is no heat. There is air blowing but it’s rather cold. I go back look at things, start googling the problem, trace the schematics for the furnace, play with the thermostat, leave a callback to an HVAC guy. Nothing. Meanwhile the temperatures indoors slide like Santa down the chimney (got down to 62). I play with the furnace a bit more, trace the wires, check gas, try to identify components and link them to the diagram when I notice a thick wire that appears to have cracked insulation. Looking at it closely it turns out to be an air tube that has is been slit by a metal cover that guards access to the air filters that I’ve just changed. The poor thing sticks out on top of a metal blower, right under the metal cover for the air filters. Drop the cover and the thing is decapitated by the sharp metal edges. As it turned out the tube plays a crucial role in detecting air flow before the gas is lit up. Couple drops of superglue, teflon tape and it’s back to normal. Now, only if the designers moved it out 2 inches or made it thicker or made it out of  plastic, that is also easily distinguishable from a wire, that could have made a whole lot of difference. On the bright side, I’ve learned a lot about furnace maintenance in these cold and treacherous hours.