Whether winter is gearing up or winding down, nobody wants to be pulled from a peaceful evening binge watching Netflix to deal with the sudden demonstrations of an ailing or aging furnace. A furnace that’s leaking, whistling, banging or just not keeping you warm is enough to ruin anyone’s mood.
You can avoid a lot of unexpected winter mishaps with a regular maintenance program. But what if you haven’t exactly been diligent about it? Or what if you know that your furnace is on the way out but have been trying to squeeze whatever juice is left before replacing it?
These are some common furnace problems that will make themselves obvious and require attention. We’ve included some possible culprits and a few dire warnings for when you should stop and call a professional for help immediately.
1. Why Is My Furnace Leaking?
A puddle of water under any appliance usually isn’t a good sign, but it’s not necessarily the end of the world. You can expect a certain amount of condensation from high-efficiency gas furnaces. This condensations is channeled into a floor drain so a clogged drain may be the cause of your “leak”. Fixing the leak is a simple matter of cleaning the drain. Clogged condensation tubing or even a break in the line are other common causes.
A faulty secondary heat exchanger can also result in leaking. If that’s the case, and especially if your furnace is starting to show its age, then replacing the furnace is likely to be far more cost-effective than repairing the heat exchanger.
If your air conditioner and furnace share an internal drain, a clog in that drain could be the cause of water buildup as well.
Or the leak might have nothing to do with your furnace at all. If you have a humidifier, the leak could be coming from a clog or damaged line in that unit. A professional will know what to look for and be able to remedy the problem quickly.
2. Why Is My Furnace Making That Noise?
It could be a whistling, buzzing or vibrating noise. Or your furnace could just be louder than usual, gone past “white noise” into “red rage” as you grab an aspirin for your headache.
Strange noises could have any number of causes, from the simple to the dangerous. Once you identify the noise, be cautious about how you proceed, and when in doubt always call a professional.
Whistling – especially coming from vents – could simply mean that there are gaps around them where air is getting sucked through. Tighten the screws or replace the grate if it’s damaged or bent.
Whistling can also be caused by dirty filters, as your furnace tries to pull air in through any tiny hole that isn’t clogged. Change your filters to see if that alleviates the problem. Your health will thank you!
A rattling or vibrating sound can mean that something is loose. Loose ducts or pipes, or even the furnace itself rattling against the floor can be the culprit. Even the motor bearings may be to blame. As they wear out with age, the motor may “bounce” as it runs, causing a rattling sound.
A gap between the duct and the furnace can be easily solved with a bit of duct tape. Screws around the ducts can be tightened to stop rattling. If motor bearings are the problem, you’ll probably need a professional to replace them.
3. Why Does My Furnace Make a “Bang” When It Turns On?
A bang is definitely a noise, but we gave this its own category because unlike annoying but generally harmless rattles, whistles and buzzes, this sound can be potentially dangerous.
A bang or loud “pop” coming from your furnace can mean that the furnace burners are dirty. The dirt causes an ignition delay, which in turn causes a buildup of excess gas. The bang is a result of the gas finally igniting in what amounts to a small explosion. This can actually crack your heat exchanger, which is an expensive repair – not to mention the danger of hosting a mini-explosion every time your furnace fires up.
If you hear a bang, don’t mess around. Turn the furnace off and get a professional in to look at it.
4. Why Won’t My Furnace Turn On?
Few things make your heart – or home – run as cold as turning on the furnace to the sound of… absolutely nothing. If this happens to you, start by checking some of the obvious problem spots.
First, be sure your thermostat is set to “heat”. You’d be surprised how many times this simple mistake can cause panic! Then try raising the temperature to see if it kicks on eventually. If that happens, the problem is likely the thermostat sensor and not the furnace.
Next, check for a tripped circuit breaker, which can happen especially after a storm or power outage. If it’s early in the season and you’re turning the furnace on for the first time, check to be sure that your friendly neighborhood rodent hasn’t chewed through any of the wires. Double check that none have become corroded in summer humidity.
You can also check to see if the pilot light is on. It’s not uncommon for them to blow out, and you can relight yours with a match if necessary.
Of course, the issue could also be with a malfunctioning motor, transformer, control board or other component. Call in a professional if you can’t identify and resolve an obvious problem.
5. Why Is My Furnace Blowing Cold Air?
A furnace that turns on but won’t blow hot air is just as aggravating as one that won’t turn on at all.
If the air is warm but not hot, the problem could be the filters again. Clogged filters can cause a host of problems, from poor efficiency to damaged components. If it’s been a while and yours are looking worse for the wear, swap them out for high quality new filters and see if that helps.
A dirty burner assembly could be another cause of the problem, especially if you aren’t taking regular care of your system. Carbon particles build up over time, eventually preventing the jets from igniting. Have a professional clean the assembly before it becomes so clogged that the furnace stops blowing any warm air at all.
Other component failures – like a bad air handler – can also be to blame. That can lead to all sorts of other breakdowns, so don’t delay in having a professional clean and inspect your system.
6. Why Won’t My Furnace Turn Off?
It’s one thing when your furnace won’t turn on, leaving you in the cold. It’s another entirely when it won’t turn off, leaving you to lament your next energy bill.
Before you panic, start with the most common and obvious causes. First, check the thermostat to see if your system fan is set to “on.” It’s an easy thing to miss, but if your fan is set to “on” then it’s going to stay on, making you think your furnace is constantly running. If you want the blower to turn off when the furnace turns off, then set the fan to “auto.”
Another common cause is one you should be familiar with by now – clogged filters. Considering how many times bad filters have come up as the cause of a furnace issue, it might be a good idea to get in the habit of changing yours regularly!
Clogged filters restrict, air flow, which can cause the temperature inside the furnace to rise. As a result, the safety switch remains open so the fan can run continuously to regulate the temperature. If that happens, chances are your furnace is overheating and that can cause serious damage unless it’s remedied.
7. Why Does My Furnace Keep Turning On And Off?
When your furnace constantly turns on and off it’s called “cycling.” That not only puts wear and tear on your system but requires more electricity and can increase energy bills. Cycling typically happens when the furnace overheats, which triggers a safety mechanism that shuts down the furnace. After a short cooling down period, the furnace starts up again and loops through the same cycle.
As we mentioned previously, clogged filters can be one cause of overheating. The blower stays on in an attempt to regulate temperature and the furnace cycles on and off repeatedly. Blockage in ductwork or at the exhaust vent or chimney can also cause cycling. Check for things like debris blown there after a storm, leaves, or birds’ nests.
But there could be a more ominous cause of cycling – a leaking heat exchanger. Not only can that cause your furnace to overheat but it can emit deadly carbon monoxide gas. Don’t fool around with this one. If you notice your furnace turning on and off constantly, have a professional take a look immediately.
Your furnace is an investment that should keep you warm, safe and comfortable through many winters. If your furnace is leaking, banging, blowing cold air or simply aging, get in touch with us for a free consultation and estimate. And if you haven’t been taking care of your furnace the way you want it to take care of you, let’s talk about a maintenance program. We can help keep your investment working for you for a long time.