Hot wax smell?

[dirtrich]

Not quite sure how to describe this, but here goes:
We have Two (gas) forced air heaters in our single-story home.
The main (larger) one heats all but the kids' bedrooms, which are on the far end of the house.
The heater for their rooms is in the attic, w. the thermostat in one of their rooms.
The programmable thermostat and heater were installed new about five years ago.
None of us have ever programmed the thermostat, just set the temp. and leave it alone.
Over the last few months the thermostat has been occasionally/mysteriously setting itself to a higher temp. at night, typically in the mid-seventies range.
This morning I smelled a hot wax smell at their end of the house and when I went to investigate I saw the thermostat set to 84 degrees, the system switch in heat position, the fan switch to "on", but no fan running.
The wax smell was definitely stronger in their rooms, strongest in the room directly under the heater. Went up in the attic and gave the heater a visual once-over/sniff-over. The smell was a little stronger up there, but I didn't see anything unusual, so I unplugged the heater for the time being.The boy in the back bedroom said he woke up in the middle of the night and turned down the thermostat because it was too hot, and said it smelled strongly of hot wax.
So, I'm guessing that the thermostat went wacky; the fan motor burned out; the heater shut down.
But the hot wax smell?
I'm a little freaked out by this! Had a family chat with the boys to re-confirm that they need to come get me anytime 24/7 if there's anything unusual like that going on.

 

[Richard Cranium]

Yes, most likely burned out the motor, But have an tech. come out and check out what you need, I would also replace the thermostat.

 

[dirtrich]

Can a non-programmable thermostat be substituted? Not really wild about having a heater with a mind of its own!
And the smell....freaked out about that thing possibly burning the house down!
Always had wood stoves in my prior homes, this is my first experience with forced air heating. Liked it a lot.....until this morning!

 

[toplessHO]

heater should have a fail safe that cuts it off if heat gets too high
this may be what happened. Ive never had a programmable one go wonky
Get a good one like a honeywell. And even those have different grades

 

[LS6 Tommy]

X2 on the safeties. Shouldn't have ever got hot in there. What do you mean "unplugged the heater"? There is nothing on a gas fired warm air furnace that "plugs in" except for maybe a condensate pump or a humidifier...

Things are sounding kind of wierd.

Tommy

 

[zmaxmotorsports]

I hate programmable stats.Ill install them if people want them,But Ill give them the book and tell them to program it themselves.
Id go with a good basic non programmable stat myself.
As far as the smell Id climb up in the attic where the furnace is and start checking around for signs of heat damage.

 

[dirtrich]

X2 on the safeties. Shouldn't have ever got hot in there. What do you mean "unplugged the heater"? There is nothing on a gas fired warm air furnace that "plugs in" except for maybe a condensate pump or a humidifier...

Things are sounding kind of wierd.

Tommy

I believe the blower fan that circulates the warm air needs electricity to run, as does the circuit board that controls the whole thing.

 

[dirtrich]

I hate programmable stats.Ill install them if people want them,But Ill give them the book and tell them to program it themselves.
Id go with a good basic non programmable stat myself.
As far as the smell Id climb up in the attic where the furnace is and start checking around for signs of heat damage.

I now hate programmable thermostats too! Will replace it with a basic model.
And yes, I was all over that furnace like white on rice!
Couldn't find anything singed or discolored. Even took my temp. gun up there to look for hot spots....couldn't find anything.

 

[LS6 Tommy]

I believe the blower fan that circulates the warm air needs electricity to run, as does the circuit board that controls the whole thing.

I am very well aware of that. NONE of those items "plug in"...

Tommy

 

[dirtrich]

I am very well aware of that. NONE of those items "plug in"...

Tommy

And yet......

 

[LS6 Tommy]

And yet......

OOOhh Kaayyy....

I bet it goes to a condensate pump or a humidifier. It's VERY illegal to run your furnace off of a plug...

Tommy

 

[bigredmf]

But is it dangerous/hazardous?


Sent from my iPhone using Tapatalk

 

[pablo94sc]

OOOhh Kaayyy....

I bet it goes to a condensate pump or a humidifier. It's VERY illegal to run your furnace off of a plug...

Tommy

Umm, how else do you think the fans and control boards get their power? Does the unit magically pluck the power out of the air?

 

[red]

Umm, how else do you think the fans and control boards get their power? Does the unit magically pluck the power out of the air?

If you're talking about the furnace, perhaps it's hardwired?

 

[pablo94sc]

If you're talking about the furnace, perhaps it's hardwired?

Every residential gas furnace I've worked on was plugged into a 120V outlet.

 

[zmaxmotorsports]

Must be a southern thing.

 

[dreasoner]

If the furnace is plugged in to receptacle, how do you handle the over current protection for the furnace? Most furnaces residential gas furnaces here have a SSU or SSY at the furnace.

 

[dirtrich]

OOOhh Kaayyy....
I bet it goes to a condensate pump or a humidifier. It's VERY illegal to run your furnace off of a plug...
Tommy

Geez Tommy, you could have just said "You know, those are supposed to be hardwired in" in your first response.
Would have saved some back-and-forth.

 

[pablo94sc]

If the furnace is plugged in to receptacle, how do you handle the over current protection for the furnace? Most furnaces residential gas furnaces here have a SSU or SSY at the furnace.

I'd assume the breaker takes the hit since it's on its own circuit in the panel. I have seen switched outlets for furnaces, but again the furnace itself was plugged in and not hardwired. I'm not an HVAC guy by trade, but I've done a few service calls with my uncle in law and helped some friends out locally - never seen one not corded. It's not code here as far as I can tell.

 

[dirtrich]

I'd assume the breaker takes the hit since it's on its own circuit in the panel. I have seen switched outlets for furnaces, but again the furnace itself was plugged in and not hardwired. I'm not an HVAC guy by trade, but I've done a few service calls with my uncle in law and helped some friends out locally - never seen one not corded. It's not code here as far as I can tell.

Well that's encouraging!
I'll find out if its code here in Cal. when the tech. comes by.

 

[nadogail]

Electrical codes vary by location, what is acceptable in one area may not be in another.

Forced Air Residential Furnaces here, San Diego County, are typically plugged into a receptacle.

Over current protection is typically a circuit beaker in the panel.

 

[Chris Stapley]

Every residential gas furnace I've worked on was plugged into a 120V outlet.

I live in Ontario and work as an HVAC tech,it is mandatory law here to hardware with BX cable on any residential furnace! We also mus hard wire a switch clearly marked emergency shut off with a red cover.

 

[pstnbly]

When was the last time the filter was changed. Clogged filters can cause the heat exchanger to overheat, a condition made worse by the T-stat set too high. At least once a month on the filter change, and be careful about high restriction filters.

 

[dirtrich]

When was the last time the filter was changed. Clogged filters can cause the heat exchanger to overheat, a condition made worse by the T-stat set too high. At least once a month on the filter change, and be careful about high restriction filters.

Filter was changed out a couple months ago.

 

[LS6 Tommy]

Umm, how else do you think the fans and control boards get their power? Does the unit magically pluck the power out of the air?

It's hard wired. By code. You cannot use a plug in cable for a permanent device.

Tommy

 

[DC73]

It's hard wired. By code. You cannot use a plug in cable for a permanent device.

Tommy

It's not code here. I've never seen a hard-wired furnace around here - only ones plugged into outlets like the OP's. I'm told some builders wire furnaces in attics to an AC disconnect. However, an isolated circuit on its own breaker is required.

DC

 

[dirtrich]

It's not code here. I've never seen a hard-wired furnace around here - only ones plugged into outlets like the OP's. I'm told some builders wire furnaces in attics to an AC disconnect. However, an isolated circuit on its own breaker is required.
DC

Which is what we have--isolated circuits w. their own breakers.

 

[LS6 Tommy]

How does it pass inspection? I'm not a licensed electrician, but NEC 422.16 and 400.7 both forbid use of a flexible cord for a furnace based on it not being a temporary use, a furnace does not meet the NEC definition of an "appliance" and also a felxible cord cannot be used as a substitute for hard wiring a permanently installed device.

Just asking...

Tommy

 

[James-W]

Here in S.E. Wisconsin (at least where I live) it must be hard wired. Not only does the natural gas house furnace need to be hard wired, but the natural gas heater in the garage must be hard wired as well.

 

[G_P]

I've seen a few plug in gas furnaces here in CT as well. Never large "whole house" units though. These were small free standing propane furnaces in summer cottages that were only used rarely if people were there late in the fall.
I have an oil fired forced hot air furnace, and it's hardwired to a disconnect that is on the wall next to it.

 

[DC73]

How does it pass inspection?

Not sure. All I know is that no builder around here hard wires a furnace.

One thing that is different from your area is that we generally don't have basements for mechanical equipment. Most furnaces are installed in a dedicated closet either in the house or in the garage (most). That closet typically shares a water heater but nothing else. If a furnace is not installed in a dedicated closet, it'll end up in the attic.

When I built my workshop last summer, I specifically asked the electrical inspector about my heater closet and how best to wire out for the new furnace. He told me to install a dedicated duplex outlet on its own breaker.

DC