24 Sep 6 Signs That You Have a Broken Furnace (And How to Fix Them)
Winters in Seattle are not usually that bad, but they can get down into the ’30s. And it’s on nights like this that you don’t want to wake up to find you have a broken furnace and there is no heat. Fortunately, there are some signs you can look out for to let you know your furnace needs a bit of TLC. If you don’t want to get left out in the cold this winter, read on to learn more.
Carbon Monoxide (CO) Gas Buildup
It’s easy to succumb to CO poisoning because the gas is both colorless and odorless. Since we humans can’t detect the gas ourselves, we must rely on CO detectors to keep us from harm.
Even still, 400 Americans die every year from accidental Carbon Monoxide poisoning. CO detectors often end up getting installed on or near the ceiling of a room like a fire alarm. This is an issue because Carbon Monoxide gas is heavier than air. If a detector is near the ceiling, the entire room has to fill with the deadly gas before it goes off. Instead, install CO detectors about two to three feet off the floor.
What Does This Have to do With my Furnace?
CO gases build-up when fossil fuels, like those used in your furnace, do not fully burn off or burn improperly. So, if your CO detector picks up gas, it could be because your furnace isn’t burning fuel as it should.
Even if your Carbon Monoxide alarm doesn’t go off, be wary if you start feeling any of the following symptoms:
- Flu-like symptoms
- Fatigue or extreme sleepiness
- Sense of unease, phantom noises and/or hallucinations
If you are concerned you have Carbon Monoxide poisoning, turn off the furnace, get out of the home and seek medical attention immediately.
Your Home Doesn’t Maintain Consistent Temperatures
Do the temperatures in your home fluctuate wildly? Do you find yourself tinkering with the thermostat all day? Or maybe your home just never gets quite warm enough? If so, then your furnace isn’t doing its job. This could be for many reasons: a bad thermostat, a clogged furnace filter, or even a dirty blower gone bad.
The thermostat is a good place to start when you get cold, especially if it’s a mechanical thermostat. It’s also one of the most overlooked pieces of equipment when this happens. Don’t laugh, but do yourself a favor and go check that it’s set to the correct temperature. Now that we have ruled that out, let’s get down to business.
Level the Thermostat
Mechanical thermostats use a mercury-based sensor to determine room temperature. If your thermostat isn’t level, it can’t function the way it needs to.
Here’s what to do:
- Remove the thermostat from the base
- Loosen the base screws
- Put a bubble level on the built-in leveling posts or on the flat area at the top or bottom
- Adjust the base until it’s level
- Tighten the base screws and replace the thermostat
Calibrate the Thermostat by Adjusting the Heat Anticipator
The heat anticipator tells your thermostat when to turn the furnace blowers off. The anticipator is a small metal tab you can move along a metal plate. The metal plate has etched measuring ticks to help you adjust it. Note that the word “Longer” is on one side of the plate. If the room stays too hot or too cold for extended periods of time, move the tab closer to the Longer side. If the furnace keeps cycling on an off, move the tab away from the longer side. Test your new settings for an hour or two and adjust again as necessary.
Clear the Thermostat of Dust and Debris
Remove your thermostat from its base and check its internal workings for dust and debris. If you find any, gently clean it off with a dry rag or vacuum cleaner.
Check the Date and Time on Digital Thermostats
If your furnace is coming on at weird times of the day, it may be on a timer. Check to see if your thermostat shows the correct date and time. If not, reprogram it and it should start cycling on and off the way you want it to.
1. The Filter
The furnace filter helps the furnace blower by preventing debris from getting to it. It’s important to change this filter to keep the blower in tiptop condition.
Check the filter each month. Change it when:
- You can’t see light shining through the filter
- There is a dirty smell coming from the vents
- There is dust around the furnace and vents
When you change the filter, turn the furnace off so no air comes through the vents. Also, check to make sure you put the filter in the correct way. Filters only catch debris from one direction. If you put it in backward, the filter won’t be able to do its job.
2. The Blower
Sometimes the blower gets dirty and stops blowing air the way it should. You can remove the blower from its housing and clean it with a brush and vacuum, but be careful. It’s easy to throw the blower out of balance. This may be a job best left to a professional.
3. Unusual Odors
When you first turn on your furnace after it has been sitting all summer, don’t worry if you smell burning dust. It’s common for it to build up when the unit hasn’t been on for a while. It’ll burn off in no time. Other than that…If you smell something foul coming from your vents or furnace, there is a good chance something foul is going on.
4. Musty Smells
If your furnace kicks on and your house starts smelly musty, that means you have a mold problem. A technician can inspect the furnace itself but if they don’t find anything, it’s in your ducts and vents. Those need to get cleaned ASAP to keep you from getting sick.
5. Rotten Eggs or Sewage
When the heat exchanger goes bad in a furnace, it reeks… literally. Some people say it smells like rotten eggs, others say it’s sewage. There have even been people that say it smells sour or that it burns their nose. It smells like this because it’s a warning. Turn off the furnace immediately and call an expert. While it’s on, dangerous levels of CO gas are getting dumped into your home.
6. Burning Plastic
It’s possible for your furnace to short out or have some other type of electrical malfunction. This can cause wires to heat up to a point they melt or even burn. If your furnace starts smelling like burnt plastic, turn it off immediately. It’s time to call a professional.
A Yellow Pilot Light
A healthy pilot light flame is blue and even. On the other hand, a yellow flame means that the gas coming out of your furnace isn’t fully burning off. This is yet another indicator that Carbon Monoxide is building up in your home. You guessed it. Turn off your furnace right away. The most common cause of the yellow flame is dust build upon and around the pilot light or igniter. If that’s the case, you can try to resolve the issue yourself by gently cleaning it, but it is a risky procedure. If you damage the pilot light or reinstall incorrectly, you may find yourself in even greater danger. Call a professional if you’re in any way uncertain.
The Blower Runs Non-Stop
Furnaces have a limit switch. This switch detects the temperature of the furnace and tells the blower when to turn on and off. It can also detect when the furnace is too hot and prevent the unit from turning on altogether. When the limit switch starts to malfunction, the blower doesn’t get the message to stop working and continuously blows air. If the limit switch fails altogether, this breaks the circuit to the furnace and the unit won’t even turn on. If the furnace gets too hot, a working limit switch causes the furnace to turn off so it does not overheat. When this happens four or more times, the controlling computer forces the furnace into a Hard Shutdown mode. While in this mode, the furnace can’t turn back on until it gets serviced.
These days, furnaces are built to last for 20 to 25 years as long as they are well maintained. if your furnace is getting up in years it’s time to replace it when:
- You’ve had to call in a technician two or more times in the past two years
- A repair is going to run you more than 20% of the furnace’s original cost
- Your furnace’s Annual Fuel Utilization Efficiency (AFUE) is lower than 70%
If you think it’s time for a new furnace, consult a technician about your options so you know how best to proceed.
Got a Broken Furnace?
If you’ve read through this article and determined you need some help, take a look at our furnace repair FAQ’s. If you still can’t figure it out on your own, reach out for help. Furnaces are complicated pieces of equipment and can be quite dangerous if they aren’t handled with care. That’s why Fischer Heating and Air uses licensed technicians to make sure your broken furnace gets fixed right the first time. If you’re ready to schedule a repair or simply want to ask us a question, don’t hesitate to contact us! We are happy to help!