Cold House This Morning

[91stealthes]

I woke up this morning to a 60 degree house. The thermostat is programmed to drop to 65 overnight and return to 68 by 7am, which it did not.

I first checked to make sure my wife didn't change anything, as she recently changed it to run the fan continuously. Everything checked out at the thermostat.

I went to the furnace and powered it down, then back on. The fan kicked on, pilot never lit and the fan shut down after about 30-45 seconds. After the fan kicked off, I heard a continuous humming noise, not a transformer hum either.

I took the cover off and cycled it again with the same results.

I tracked the humming noise to black wheels (which look similar to a bullseye). I manually moved them by hand and realized they were warm. It also had a mechanical smell.

After manually moving these wheels clockwise and counter-clockwise, I cycled the power again. This time, the fan kicked on for about 30-45 seconds, then shut off. Then the wheels spun for about 3 seconds. Again, not ignition or heat, but still the mechanical smell.

It is currently powered off via the switch on the furnace.

Another item I noticed, and never did before, is that there was a furnace filter on the back of the furnace housing. Was the installer just lazy and did not put sheet metal over the hole, or should this filter be there?

The furnace is a Carrier Model 58STA166-20, Series 100.

I have attached a few photos below.

Thanks for any help. I figured I would ask here before calling my HVAC individual.

I am unsure if the wheels are not spinning and getting mechanical smell because the igniter is not igniting or if that part is not allowing the igniter to ignite.

Cheers,
J

[Senior Tech]

Sounds like mechanical or electrical failure of the inducer. Time to call the pros.

Igniter will not power up until motor runs and proves other safety features within the unit.

[motoguy128]

I'm guessing died and early dead form cycling 3X more often than a properly sized furnace would have. Might just the the start capacitor on the motor... I think those have one. That's a 125kBTU output furnace by the namplate. Unless it's a huge home, that's a big furnace... really big... like could heat most 3000+sqft homes at -5F with ease.

[Kevin Weaver]

i have seen dead birds in the pipe.

[vstech]

those three "wheels" are just mounts for the fan, they do not turn on their own.
if the small fan in the center is not turning, you will get no pilot.
if the fan that runs for 30-45 seconds is the one in the picture, the system either does not know it's running, or there is a blockage in the chimney, or the ignitor is not working.
either way, that's a lot of things to check... the system needs service to find out why you get no pilot. give him the model of the furnace so he brings the right parts with him.

[vstech]

by the way... I don't think your furnace has a pilot. it looks like the ignitor just lights the entire burner assembly. so... I do not recommend you trying to light the furnace with the door off...

[91stealthes]

Sounds like mechanical or electrical failure of the inducer. Time to call the pros.

Igniter will not power up until motor runs and proves other safety features within the unit.

Thanks. I assumes it was a fail safe, but wondered if it was the inducer that was the culprit. I'll call Tim. I know I am not supposed to use you or take your advice because you don't have an asterisk, but where are you located in Illinois? Thanks again for the support!

I'm guessing died and early dead form cycling 3X more often than a properly sized furnace would have. Might just the the start capacitor on the motor... I think those have one. That's a 125kBTU output furnace by the namplate. Unless it's a huge home, that's a big furnace... really big... like could heat most 3000+sqft homes at -5F with ease.

What do you mean by cycling 3 times more than a properly sized funace? The main 2 levels of the house are 3100 sf. The basement is also finished and has ductwork making another 1500 sf. So, the furnace is heating around 4600 sf.

i have seen dead birds in the pipe.

Makes sense, as the inducer couldn't expel the air. This could be a possibility as I have seen birds take residence in my neighbors vents.

those three "wheels" are just mounts for the fan, they do not turn on their own.
if the small fan in the center is not turning, you will get no pilot.
if the fan that runs for 30-45 seconds is the one in the picture, the system either does not know it's running, or there is a blockage in the chimney, or the ignitor is not working.
either way, that's a lot of things to check... the system needs service to find out why you get no pilot. give him the model of the furnace so he brings the right parts with him.

Thanks. After learning what the inducer does, it makes sense that the igniter would not ignite. I'll call Tim. When I used him in my townhouse, he would sometimes diagnose over the phone. Looks like I'll be leaving work early today.

by the way... I don't think your furnace has a pilot. it looks like the ignitor just lights the entire burner assembly. so... I do not recommend you trying to light the furnace with the door off...

I mistyped. You are correct that it is an igniter, not a pilot.



Thanks everyone for the input. I'll call my HVAC gentleman and see what he has to say. Finger's crossed it is just a clogged exhaust and not a bad inducer or gas valve/regulator.

[dandyme]

Thanks. I assumes it was a fail safe, but wondered if it was the inducer that was the culprit. I'll call Tim. I know I am not supposed to use you or take your advice because you don't have an asterisk, but where are you located in Illinois? Thanks again for the support!

oh no! ST has been called out

[91stealthes]

oh no! ST has been called out

Haha. Hey, I'm just following the forum rules (I actually read them before posting). I do find it strange (s)he is global moderator, but doesn't have an asterik. Did (s)he not pay their dues?

Update: My guy's company no longer works in residential and now focuses on commercial more toward the city. I came home after my meetings and looked again and tried to fire her up, same thing. But now I spun the "wheel" (now that I spent more time with it, looks like a fan) after the fan shut off. It continued to spin, the ignitor glowed and wahla, the gas burners ignited. It seems to be working fine now, but that "wheel/fan" sounds like it needs lubed. I am going to call the gentleman my HVAC guy recommended to set up an inspection, but want to know if this needs replaced, or just lubed before he gets here.

Thanks!
J

[small change]

there aren't any real oiling ports on that inducer motor to oil

The motor is a sealed bearing motor so more than likely you will need an inducer assembly.

[91stealthes]

there aren't any real oiling ports on that inducer motor to oil

The motor is a sealed bearing motor so more than likely you will need an inducer assembly.

Thanks. Motor assembly or just the motor? HVAC gentleman is calling Carrier now. He hasn't told me prices, but looks like quite a difference between assembly and motor only.

[hurtinhvac]

DO NOT spray any sort of lubricant anywhere near it.

[beenthere]

Haha. Hey, I'm just following the forum rules (I actually read them before posting). I do find it strange (s)he is global moderator, but doesn't have an asterik. Did (s)he not pay their dues?

Thanks!
J

LOL, his is invisible, like mine, and all other moderators here, but he is approved to post in the AOP forums.