Furnace Troubles and How to Troubleshoot Them in Upstate NY & Vermont
If your furnace stops heating, check the thermostat, filter, power switch, breaker and fuel supply before calling. Many winter no-heat calls come down to one of these. If none fix it, call for service.
Check the thermostat first
Make sure it is set to Heat, set a few degrees above room temperature, and the batteries are fresh. A programmable or smart thermostat can lose its schedule after a power flicker, and a thermostat on an exterior wall or near a drafty door can misread the room. These are free checks that solve a surprising number of calls.
Filter, vents and airflow
A clogged filter makes the furnace overheat and shut off on its limit switch, then restart in a cycle. Check the filter, and make sure supply registers and return grilles are open and unblocked. In winter, filters load up with dust and pet hair faster than you expect.
Power and the switch near the furnace
Furnaces have a service switch that looks like a light switch, usually on or beside the unit or at the top of the basement stairs. It gets bumped or flipped off during cleaning. Check the breaker too. Also check any door switch on the blower panel. If a breaker trips again right away, do not keep resetting it.
Fuel supply: oil, propane and gas
Rural Upstate and Vermont homes often run out of fuel. Check the oil gauge or propane tank level before anything else. Oil systems can also lose prime or have a clogged filter, and in extreme cold an outdoor oil line can gel. If you are on natural gas, make sure other gas appliances work, which tells you whether supply is the issue.
Ignition, igniter and flame sensor problems
On gas and propane furnaces, a dirty flame sensor or a failed hot surface igniter makes the furnace try to light and then shut down. You may hear clicking, then the blower stops. These are quick repairs for a technician. Do not use a screwdriver on gas parts yourself.
When to stop and call
Call if the furnace short cycles, makes loud banging or grinding sounds, smells like gas, shows soot or has a lit flame that is yellow. Superior CO-OP HVAC books no-heat calls any hour through our 24/7 line at (518) 333-7431, and our no heat help page walks through the next steps. See emergency repair.
Prevention and replacement
Annual tune-ups catch most of these failures before they happen; a gas or propane furnace tune-up is $210.83 and an oil furnace is $276.67. See our maintenance programs. If the furnace is old and failing often, use the "$5,000 rule" of thumb and compare replacement with a cold-climate heat pump. Book a free in-home estimate.
Strange noises and smells
Banging, squealing and grinding each point to different problems, from delayed ignition to a failing blower bearing. Burning dust is normal on the first cold day of fall, but a burning plastic smell, a rotten egg odor or a sooty smell is not. A gas or propane smell means leave the house and call from outside. Oil smells near the burner point to leaks or incomplete combustion. Shut the furnace off and call for service rather than running it.
None of these are worth risking a repair attempt on, since gas, oil and electrical parts all carry real hazards.
Short cycling and uneven heat
A furnace that turns on and off every few minutes may have a dirty filter, a blocked vent, a bad flame sensor, an oversized unit or a thermostat in a bad location. If some rooms stay cold while the furnace runs, ducts may be leaking or blocked. See our guide to uneven airflow and our Home Comfort Diagnostic. If the furnace is more than 15 to 20 years old and has frequent problems, the "$5,000 rule" of thumb helps decide whether to repair or replace; the details are on our repair vs. replace page.
Frequently asked questions
Why is my furnace not heating?
Superior CO-OP HVAC finds the most common causes are thermostat settings, a clogged filter, a switched-off service switch or tripped breaker, an empty fuel tank or a failed igniter or flame sensor. Check those basics first, then call for service.
What should I do when my furnace stops on a cold night?
Superior CO-OP HVAC suggests checking the thermostat, switch, breaker and fuel level, then calling the 24/7 line at (518) 333-7431 if it will not restart. Keep the house closed up and avoid unsafe heat sources like ovens or generators indoors.
Why does my furnace keep turning on and off?
Superior CO-OP HVAC commonly finds short cycling from a dirty filter, an overheating limit switch, a failing flame sensor or a thermostat issue. Replace the filter and call if it continues, since repeated cycling wears parts quickly. Replace the filter first and call if it continues.
How often should a furnace be serviced?
Superior CO-OP HVAC recommends once a year, in the fall before heating season. Tune-ups are $210.83 for gas or propane furnaces and $276.67 for oil furnaces, and maintenance plans bundle spring and fall visits. Plans make the yearly cost predictable.
Does Superior CO-OP HVAC repair all furnace brands?
Yes. Superior CO-OP HVAC repairs and maintains all brands of furnaces, boilers, central AC and water heaters. We give a written quote before repair work begins, and the diagnostic trip charge is $250. Written quotes always come before repair work.
Thinking about a heat pump? Superior CO-OP HVAC is a Mitsubishi Diamond Contractor ELITE serving Upstate NY & Vermont. Get a free in-home estimate, run the Heating Cost Calculator, or call (518) 719-5614.