So, we have this furnace and it’s loud as hell. Like extraordinarily loud. One day i got fed up with the noise and cracked the thing open. There were a lot of wires in there. Luckily, there was also a wiring diagram. Unluckily, the actual wiring did not resemble the wiring diagram. Since then, I’ve been putting up with it while we’ve tried to get our contractor to come in and fix it.
Last tuesday I got fed up with it and tried to fix it. After messing with the thing for a few minutes, i realized i was missing a few quick disconnects, so i put the thing back together and left it for the weekend. furnace 1, jason 0.
Fast forward to Sunday. I head to the hardware store and pick up some quick disconnects and get back at it.
Our furnace is actually just a blower and a pump. It pumps in hot water from our tankless water heater and blows air over the radiator coil to warm it and then push it through the venting system. According to the manual, the blower has three speeds: high, medium, low. When heating, the blower is supposed to be set to low. The wiring had us hard coded to high, and that wasn’t the only problem.
Okay, time to get to work. The furnace is set for a three wire system and only two of the wires were set. I bring in the third wire. furnace-1, Jason-1.
next, the wiring diagram says you can select two of the three speeds. I reset the control switch to use medium cool and low for heat. furnace-1, jason-2.
after that, we have a time delay relay control which wasn’t wired properly. So i fix that up. Furnace-1, Jason-3.
All done! Woot! Ok, moment of truth. I turn the power to the furnace back on. It immediately starts to blow. doh. that’s not good. it should wait for the signal from the thermostat. damn. furnace-2, jason-3.
I turn it back off. go back into the furnace. observe the wiring diagram. the wires the LO are both yellow. maybe i hooked them up to the wrong ends? I reverse the ends and turn the power back on. nothing happens. woot! i smell smoke. DOH! i quickly turn the power back off as the thing fries. furnace-3, jason-3.
ok, stay cool. maybe we didn’t completely fry it. put the wires back. turn the power back on. it immediately starts blowing again.
I check all the wiring again. it’s text book. exactly like the wiring diagram. hmmm . . . . . hmmm . . . . i look at the time delay relay. I look at the wiring diagram. the time delay relay is mounted with a 90 degree rotation. i redo the wiring on the TDR to compensate, turn the power back on, and the furnace stays still. Good. no smoke. even better. I head upstairs and turn the thermostat up. The thermostat clicks, the furnace turns on and it’s quiet as a . . . . well, not exactly a mouse, but it’s much quieter. boo. yah.
Score one for the DIYers!