Cold air keeps blowing through your vents. You checked the thermostat three times already, still nothing. Half your house feels like a freezer while your heating bills keep climbing. Sound familiar? Here’s what most people don’t know: heating system repair calls aren’t always necessary. About 70% of furnace breakdowns are caused by simple issues. Dead batteries. Dirty filters. A switch someone bumped by accident. Takes five minutes to check, costs nothing to fix.
But some problems are serious. Gas leaks don’t announce themselves politely. Carbon monoxide has no smell. Yellow flames mean danger, not just inconvenience. Let’s determine which one you have.
Why Is My Heating System Not Working?
Five things that prevent the furnace not heating from producing heat: your thermostat is set to the wrong temperature, the filter is completely clogged, a breaker tripped and cut the power, your pilot light went out, or something’s blocking the vents. Fix any one of these, and you will have your heating system perfectly fine. No repair bill needed.
Here’s what stops heat:
- The thermostat is making strange heating noises because somebody changed it from “heat” to “cool” last October and forgot, or the batteries died last month but the screen still glows, so you didn’t notice.
- Power went out between your electrical panel and the furnace, either due to a tripped breaker during last night’s storm or to someone accidentally hitting the basement light switch.
- The pilot light died from a draft coming through your basement, or your newer furnace’s electronic starter quit working and just clicks uselessly when it tries to light.
What Should You Check When Your Furnace Is Not Heating?
Start at your thermostat. Make sure it reads “heat” and is set at least 5 degrees higher than your house currently feels. Then check if a breaker flipped. Pull your filter out. Can you see through it? Lastly, ensure the furnace power switch is on.
Takes about five minutes to review everything and check for uneven home heating. Start simple, then work your way up to slightly more complex tasks.
Thermostat and Power Issues
Do a quick walkthrough of your thermostat. Does it say “heat” or “cool”? If it shows cool, then you can fix it by turning it to heat. We get calls from people all the time, their furnace “stopped working” in November because it’s still set to AC mode from September.
The temperature number needs to be higher than what your house feels like. Not a little higher. At least 5 degrees higher, or the furnace won’t produce heat as your house needs. Battery-powered heating systems stop communicating with your furnace when the batteries get weak, even though the screen looks fine.
Check these power problems to figure out heater failure signs:
- Your breaker box has a switch. When your furnace overloads and draws too much power, it trips, especially during cold snaps when systems run all night.
- The light switch beside your furnace, which looks like all your other light switches, is often turned off without realizing it controls the entire heating system.
- Their thermostat batteries should be replaced every September, before the heating season begins. Waiting to die implies you will wake up late, at 2 am, wondering why your furnace has stopped.
Dirty Filters Causing Problems
Your filter catches all the pet hair and dust floating around your house before they get into the furnace. Your furnace tries to pull air but can’t, and then shuts itself off before something overheats. It is because of the smart safety feature. Winter makes this worse because your furnace runs nonstop, filling the filter in weeks instead of months.
Fix airflow like this:
- Find your filter near that big metal blower box on your furnace. Sideways furnaces have it slide out from the side, and standing furnaces hide it behind the top or bottom door panel.
- Hold it up to light from a window or lamp; if light comes through easily, it’s still good. If you can’t see any light at all, throw it away and buy a new one today.
- Walk through your whole house, opening vents that got closed, moving furniture away from floor registers, then go outside and shovel snow away from those vents on your house’s exterior wall.
Pilot Lights and Ignition Systems
Older furnaces maintain a small flame that burns continuously. The ignition system continuously powers your heating system. This means, no flame, no heat. You can light it yourself using the instructions attached to your furnace. Try twice. If it won’t stay lit, stop doing yourself and call a professional. If you hear clicking when the furnace starts, it’s normal. If it clicks continuously and nothing happens, you may need to address common furnace problems & how to fix them.
Watch for these ignition signs:
- The pilot keeps going out after you light it. That’s usually a faulty thermocouple, the safety sensor that tells your gas valve the pilot’s actually burning instead of just leaking gas into your basement.
- The gas valve handle is pointing sideways instead of along the pipe. Sideways means closed, and no gas reaches your pilot light. Along the pipe, the flow is open, and gas flows normally to generate heat.
- Yellow or orange flames instead of blue indicate incomplete combustion, which can produce carbon monoxide, a toxic gas. Turn off your furnace immediately and call for heating system repair.
When Should You Call a Professional To Fix Your Heating System?
Call a professional immediately if you smell rotten eggs, see flames that aren’t blue, hear grinding or banging, find water on the floor around your furnace, or nothing you tried restores heat after half an hour of troubleshooting.
These problems need professionals now:
- A rotten-egg smell near your furnace indicates a gas leak. Get everyone outside immediately. Don’t touch light switches or your phone until you’re outside. Call the gas company first, then the professional second.
- The continuous on/off cycles every couple of minutes, rather than the normal 15-20 minute cycles, are evidence of short-cycling due to a cracked heat exchanger, an ineffective thermostat, or oversizing of a furnace to the size of your house.
- Furnace water: More modern, high-efficiency furnaces can produce their own water, but it runs through the pipes rather than onto your basement floor, where it can damage everything it comes into contact with.
Final Thoughts
Most heating breakdowns in Derry are due to simple fixes that you can do yourself. Wrong thermostat setting. Gross filter. Flipped breaker. Takes five minutes, costs nothing, and gets your heat back on. But you need to know when to stop trying. For example, if the furnace isn’t heating due to unusual noises, gas odors, or signs of failure such as yellow flames, call a professional.
Daigle Plumbing, Heating & Cooling has been doing this for four decades. Fast response. Right diagnosis. Permanent fix. Don’t wait until midnight, when it’s freezing outside, and your furnace stops working. Contact our furnace repair professionals for heating system repair in Derry, NH. Licensed technicians, fast service, no surprises on the bill.
FAQs (Frequently Asked Questions)
Why Is My Heating System Blowing Cold Air?
Your fan is likely set to run continuously rather than only when the furnace generates heat. Or your filter’s so packed with junk that air blows through, but doesn’t get heated. It could also be that your pilot or electronic starter isn’t lighting the burners while the fan continues to spin.
How Often Should I Replace My Furnace Filter?
The low-cost furnace filters are replaced every month from October through March. Better pleated ones last three months if you check them monthly. If you have pets in your house, change it every two weeks, especially during cold stretches when your furnace runs hard.
Can I Relight My Furnace Pilot Light Myself?
Yeah, if you follow the directions on your furnace. Locate the pilot assembly, turn the valve to “pilot,” and hold the button down while lighting it with a long lighter. Doesn’t work after two tries? Stop and call us before you fill your basement with gas.
What Does It Mean If My Furnace Keeps Shutting Off?
That’s short-cycling. Usually means your filter’s completely blocked, your furnace overheats, your vents are blocked, your flame sensor is dirty, or your thermostat’s misconfigured. New filter first. Still doing it? Needs professional attention before expensive parts break from all that cycling.
Is It Normal For My Furnace To Make Noise?
The soft hum from the motor is normal. Air whooshing through vents, fine. Ducts banging a little when they heat up is normal. But grinding, squealing, or rumbling? Something’s breaking right now. Have it inspected before you buy a new furnace in February.
