A furnace is the heart of a home’s heating system, a vital appliance that keeps you and your family warm and comfortable throughout the colder months. But for many, the world of furnaces can seem complex. This guide will walk you through everything you need to know, from choosing the right unit to maintaining it and troubleshooting common problems.
1. Choosing the Right Furnace: A Buyer's Guide
Selecting a new furnace is a significant decision that impacts your comfort and energy bills for years to come. Here are the key factors to consider, with expert tips to help you make the best choice.
Fuel Type:
Natural Gas Furnaces: The most popular choice in the U.S. where gas lines are available. They are highly efficient, reliable, and produce a comfortable heat.
Electric Furnaces: A good option for homes without access to natural gas. They have a lower initial installation cost and are safe, but can be more expensive to run due to the cost of electricity.
Oil Furnaces: Less common in modern homes, but they are a viable option in some regions and are a powerful source of heat.
Propane Furnaces: Similar to natural gas, propane is an excellent choice for rural areas and homes without access to natural gas lines.
Efficiency (AFUE Rating): The Annual Fuel Utilization Efficiency (AFUE) rating is a percentage that tells you how efficiently the furnace converts fuel into usable heat. A higher AFUE means a more efficient unit and lower energy bills.
Standard Efficiency: 80% to 83% AFUE. These are less expensive but have a lower return on investment due to higher running costs.
High Efficiency: 90% AFUE or higher. These models have a higher initial cost but can save you hundreds of dollars in energy costs over their lifetime.
Single-Stage vs. Two-Stage vs. Modulating:
Single-Stage: The furnace is either on or off, always running at full capacity. This can lead to less even heat and higher energy consumption.
Two-Stage: The furnace has a low-fire setting for mild days and a high-fire setting for colder days. This provides more even heating and greater efficiency.
Modulating: This is the most efficient and comfortable option. The furnace adjusts its output in small increments to perfectly match your heating needs, eliminating temperature swings and maximizing efficiency.
Sizing (BTUs): Getting the right size is the most critical factor. An oversized furnace will "short cycle" — turning on and off too frequently. This leads to uneven heating, poor air quality, and increased wear and tear. An undersized unit will run constantly and struggle to heat your home. A professional technician will perform a Manual J load calculation to determine the correct BTU output for your home, taking into account factors like insulation, window size, and climate.
2. The DIY Maintenance Checklist: Simple Steps for a Healthy Furnace
Performing simple, regular maintenance can significantly extend the life of your furnace, boost its efficiency, and prevent breakdowns.
Change or Clean Your Filter (Every 1-3 Months): This is the single most important task. A clogged filter restricts airflow, forcing the system to work harder, which raises energy bills and can cause damage.
Tip: Understand your filter's MERV rating. A higher MERV rating captures smaller particles, but can also restrict airflow more, so choose one that is appropriate for your system.
Check and Test Your Thermostat: Ensure it's set correctly and the batteries are working. For a smart thermostat, check that its schedule and settings are accurate.
Clear the Area Around the Furnace: Maintain at least two feet of clearance around your furnace to ensure proper airflow and fire safety. Also, check the intake and exhaust vents on the outside of your house to ensure they are free of snow, leaves, and other debris.
Check Vents and Ducts: Make sure all air vents in your home are open and not blocked by furniture or drapes. Also, look for signs of damage or leaks in your ductwork, as this can cause significant energy loss.
Dust and Clean the Exterior: Use a soft brush or cloth to gently clean dust and debris from the exterior of the furnace and its components.
3. When to Call a Professional: The Annual Tune-Up
While you can handle some tasks yourself, an annual professional tune-up is essential for safety and optimal performance. A licensed technician will perform a comprehensive inspection that includes:
A Safety Check: The technician will inspect the heat exchanger for cracks or leaks, which can allow dangerous carbon monoxide gas to leak into your home. They will also check the gas line for any leaks.
Performance and Efficiency Check: They will measure the gas pressure, test the safety controls, clean the burners and flame sensor, and lubricate all moving parts to ensure your furnace is running at peak efficiency.
Blower Motor Inspection: They will inspect the blower motor and fan to ensure they are clean and functioning correctly, which is vital for proper airflow.
Electrical Inspection: A professional will inspect and tighten all electrical connections to prevent shorts or fire hazards.
4. Common Furnace Problems and Warning Signs
Your furnace will often give you clues that something is wrong. Knowing these warning signs can help you address the problem early and prevent a more serious breakdown.
Strange Noises: Listen for unusual sounds. A squealing sound often indicates a worn fan belt. A grinding sound may signal a problem with the blower motor's bearings. A clicking sound from an old furnace might be a faulty relay.
Odd Smells: A burning, dusty smell when you first turn on your furnace after a long period of inactivity is normal, but a persistent burning smell could indicate an electrical problem. A sulfur-like or rotten-egg smell is a major warning sign of a gas leak—turn off the gas supply and call a professional immediately.
Pilot Light is Yellow: A healthy pilot light should be a strong blue color. A yellow or flickering flame can indicate incomplete combustion, which may be a sign of a carbon monoxide leak.
Short Cycling: If the furnace turns on and off too frequently, it may be an indication that the unit is oversized, a filter is clogged, or the thermostat is malfunctioning.
Blowing Cold Air: This could be a simple problem like a thermostat set to "fan on" instead of "auto" or a more serious issue like a faulty ignition system or a problem with the heat exchanger.
5. FAQs and Final Tips
How long do furnaces last? With proper maintenance, a typical furnace can last between 15 and 25 years.
Why is my furnace blowing cold air? Check that your thermostat is on the "Heat" setting and that the fan is set to "Auto." If the problem persists, it could be a faulty pilot light or ignition, or a more serious issue with the heating element.
How often should I change my air filter? For maximum efficiency and health, check your filter every month and change it every 1-3 months, especially during peak use seasons.
Is it safe to do my own repairs? While simple maintenance is safe, you should never attempt to fix internal electrical, mechanical, or gas-related problems on your own. Always call a licensed and insured professional.
Taking a proactive approach to your furnace is the best way to ensure it provides reliable, safe, and efficient heat all winter long. By choosing the right unit and following a regular maintenance schedule, you can keep your home comfortable for years to come.