What’s That Burnt Smell When I Turn on the Furnace the First Time Every Year?

What’s That Burnt Smell When I Turn on the Furnace the First Time Every Year?

As the winter season approaches, a lot of you will be turning on your furnaces for the first time this year. And that can be a very intimidating situation for some people.
Some of you may have just moved into your first apartment and some of you may have just moved into your new home this past summer and the AC worked fine, but now you have to see how the furnace is going to work this year.
Let’s break down the gas furnace, and some of the sounds and smells you get when it comes on for the first time each year.
You should understand the nature of the furnace is to provide warm air for your home and it does that with a gas flame.

But that gas flame isn’t just flying around uncontrolled like it does, say, in a fireplace; a very structured flame is sent into the furnace.

If the flame were to roll out or overheat the furnace, a series of safety switches will engage, and tell the control board to turn the furnace off.

Whether you walk over to the thermostat or turn it on with your smartphone, the sounds and smells that you experience can be confusing.
That’s not how the air conditioner sounded when it came on, and that’s not how the air conditioner smelled when it was working either.
When the furnace gets turned on, the thermostat on the wall tells the furnace in the hallway to initiate a sequence of events that will ultimately shoot a gas flame into the firebox, or heat exchanger.

There are a few parts that come on before that flame starts to heat the home. The thermostat tells the control board inside the furnace to come on.

And the control board is the brains of the system that will control the following events. The first motor to come on will be the inducer motor. Not a large motor by any means, but it’s the one that gets rid of the fumes spent by the flame that warms your home.

The control board and a pressure switch acknowledge the inducer has come on and is working properly.
The ignitor will come on next. Usually, it’s a hot surface ignitor made of Silicon Carbide that glows red hot about 2500 degrees.

The timer on the control board then allows the gas valve to open up and pour a controlled amount of gas over the red-hot surface ignitor. That creates the flame we were talking about earlier, that shoots into the metal firebox, which is better known as a heat exchanger to us technicians.

A small flame sensor then verifies the flame is on and sends a signal to the board that everything is burning properly, and the system is safe to continue heating the home.

If the flame sensor says everything is okay, the control board then tells the blower fan to come on and the sequence is complete.

Warm air will then start flowing into the rooms until it gets to the temperature you want it to be. That whole sequence of events that happens takes about 1 minute from the time thermostat tells the furnace to start, to the time the blower turns on and gives you heat through your registers.

When the thermostat senses the room’s warm enough, it tells the control board to end the call for heating, which then cuts the flame. Meanwhile, the blower stays on just long enough to cool the furnace down quite a bit, about 60 to 90 seconds, which helps extend the life of the system.
So, how does the heat exchanger work?
Well, it “exchanges heat” by keeping the flame and its fumes inside the metal box while a fan blows air over the outside of the metal.

The heat that comes off that metal and the air from the blower is then carried into your rooms where you feel the warm air. Some people call in every fall when they turn on their system for the first time and say the system is working but there’s a strange smell coming through their vents.
Almost like a burning smell. When we get out to their home and verify all the motors are working properly, we let them know something most people don’t know until it’s happened to them.
That smell you get the first time you turn on your furnace each season is just a fine layer of dust that has settled onto the heat exchanger. The dust from your house has made its way past the air filter, past the blower assembly, and on to the metallic heat exchanger.

As the metal heats up, the dust singes or burns off and creates that sort burnt smell. It happens maybe the first couple times you turn the system on, but after that, you shouldn’t get that smell anymore.
If the smell bothers you, you can just open the doors or windows to your house and let it vent out that way for about fifteen minutes. But rest assured it’s not Carbon Monoxide, because, that’s an odorless gas that can only be picked up by a Carbon Monoxide detector.

Having said that, if you do turn your furnace on for the first time or any time this year and your home’s Carbon Monoxide detector does go off, don’t just remove the batteries and don’t treat it like it’s some nuisance alarm either.

Go ahead and step outside of the home and call the Fire Department. Let them come out to make sure everything is okay before going back inside.

It might cause a big show for everyone in the neighborhood, but who cares, it’s your family’s life on the line.
If you don’t currently have a Carbon Monoxide detector on each floor of the house and in the main hallway leading to any bedrooms, now would be a good time to head over to your local hardware store to get one of those.

Speaking of detectors in your homes – if you haven’t done so already this year, it’s time to change out the batteries in those detectors around your home.

Your local fire department usually will come out for free and help you replace those batteries.
If you have trouble reaching those detectors on your own. If they won’t and you’re in our area, just provide the batteries and we’d be happy to come over and change them for you. Otherwise, any handyman in your area would be up to the task.
As a reminder, the single-most-important-thing you can do to keep your furnace clean is to change those air filters. If the system can’t breathe in because of a dirty air filter, then it won’t be able to breathe out for you at the supply registers in your rooms either.

 
Again, if you can’t do it because you’re elderly or physically unable to reach the filter, give us a call!
Another bit of advice we’d like you to consider is to make sure there are no flammables around the furnace. Remember, we said that the furnace is either in the basement or in a hallway cabinet and these are common places to store items that tend to be forgotten over time.

A metal flue pipe that gets very hot when the furnace is turned on can be dangerous if left unattended. Broomsticks, cardboard, newspapers, clothing, and other materials can scorch over time if it’s resting on the flue pipe.
Make sure things like that and flammable liquids like varnish, lacquers, oil, and gasoline are set away (preferably outside) to keep your home safe.

Although you might be nervous to turn your furnace on that first time every year – do it.
Turn it on when it’s still mild outside. Maybe don’t wait for the first winter snap to hit before finding out your furnace doesn’t work.
If you do wait, you might find yourself at the end of a long line of other homeowners and property management companies who are requesting service at the same time you are.
So, if you don’t already have someone coming out to your house each year just to make sure everything is running safely for you and your family, we’d love to be the company that gets to do it for you.
We have a super-easy way to have it done automatically. You don’t even have to remember to call either. We call for you before each summer or winter to schedule your appointment.
Much like taking the car into your mechanic to get a check-up on it, let us come to your home and check out all these things we discussed here today is good for your peace of mind as well as your system’s longevity.
Checking your furnace’s safety switches, gas pressures, and proper airflow through the system can add many years of life to your system just by maintaining it properly, which is something we specialize in.

To recap – The nature of a gas furnace is to use a controlled flame to warm your house. And a series of safety switches are responsible for making sure that it is done in a very controlled way.
Any unexpected events that happen with the flame or other components inside the furnace will tell the control board to shut the unit down.
Once again, give us a call to check out your furnace if it’s not working properly or not heating your home or it’s noisy. Call us at Red Deer Heating and AC.