HVAC Answers: The Questions Homeowners Ask Most
Short, straight answers first — then the safe check you can try yourself, and the point where it's time to call a professional.
Troubleshooting
Why is my furnace blowing cold air?
Most often the thermostat fan is set to ON instead of AUTO, so it circulates unheated air between heating cycles — or a clogged filter tripped the furnace's safety limit switch. Safe check: set the fan to AUTO and replace the filter. Call a pro if the burners light and then die within seconds (likely a flame sensor), or if it keeps happening.
Why does my furnace keep turning on and off?
That's called short cycling, and the number one cause is a clogged filter choking airflow until the furnace overheats and shuts down. Blocked vents, a dirty flame sensor, or an oversized system can also cause it. Safe check: the filter, first. Call a pro if it continues — short cycling wears parts out fast and can signal an overheating problem.
Why won't my furnace turn on at all?
Work through the first five checks on our No-Heat Guide — thermostat, furnace switch, breaker, front panel, and fuel. One of those five solves most no-heat calls.
Why is my furnace making strange noises?
Banging at startup can be delayed ignition — book a pro soon. Squealing is usually a belt or blower bearing. Rattling is often just a loose panel. If you hear scraping metal, turn the system off and call.
Why are some rooms colder than others?
First check that vents in those rooms are open and not blocked by furniture. Beyond that, it's usually duct leaks, weak insulation, or a system that was sized for the main floor.
Maintenance
How often should I change my furnace filter?
Every 1 to 3 months — monthly during heavy heating season, if you have pets, or if anyone has allergies. A cheap filter protects an expensive system.
How often should a furnace be serviced?
Once a year, ideally in early fall before the first cold snap. See what a tune-up includes
How long does a furnace last?
Typically 15 to 20 years; oil furnaces often 15 to 25, and heat pumps 12 to 15. In the North Country, systems work hard — maintenance history matters more than age alone.
Costs & Decisions
Should I repair or replace my furnace?
Use the 50% rule: if a repair costs about half the price of a new system — especially on a unit past 12 to 15 years old — replacement usually wins in the long run. Compare installation quotes
Why is my heating bill so high?
Usually a cold snap, a clogged filter, an aging inefficient system, duct leaks, and thermostat habits — roughly in that order. Electric baseboard heat, common in Plattsburgh city homes, is the most expensive way to heat; a heat pump can cut that cost substantially.
Should I close vents in unused rooms to save money?
No. It raises pressure in the ducts, can make the furnace work harder, and often makes comfort worse. It's one of the most persistent HVAC myths.
Comfort & Local
What temperature should I set my thermostat in winter?
68°F while you're home is the usual guidance. Setbacks of 5 to 8 degrees while you're away or asleep save energy — but during deep cold, don't set back so far that pipes in exterior walls are put at risk.
Why is my house so dry in winter?
Cold outside air holds very little moisture, and heating it drops indoor humidity further. A whole-home humidifier or portable units help; watch window condensation as the sign you've gone too far the other way.
My heat pump is steaming in winter — is that normal?
Yes. That's the defrost cycle melting frost off the outdoor unit, and auxiliary heat may run while it happens. Call a pro if the unit is iced solid for hours, or if auxiliary heat runs constantly in mild weather.