What is HVAC?
HVAC stands for Heating, Ventilation, and Air Conditioning. It's the technology used to control the indoor climate of buildings — keeping you warm in winter, cool in summer, and breathing clean air year-round.
An HVAC system does three things:
Heating
Generates warmth during cold months. This can be done through furnaces (forced hot air), boilers (hot water/steam radiators), heat pumps (electricity-driven), or radiant floor systems. In NYC, boilers and furnaces are the most common residential heating systems.
Ventilation
Controls airflow and air quality. Ventilation removes stale indoor air and brings in fresh outdoor air. This can be natural (windows, vents) or mechanical (fans, ductwork, ERV systems). Proper ventilation is critical in tight NYC apartments.
Air Conditioning
Removes heat and humidity from indoor air. AC systems use a refrigeration cycle to transfer heat from inside to outside. Types range from window units and mini splits to central air and commercial rooftop units.
Types of HVAC Systems
There are several types of HVAC systems, each suited to different building types, budgets, and needs. Here's what you'll find in NYC:
Split System (Central Air)
The most common residential setup. An outdoor condenser unit connects to an indoor air handler via refrigerant lines. Uses ductwork to distribute conditioned air. Provides both heating and cooling when paired with a furnace or heat pump.
Best for: Houses and buildings with existing ductwork.
Learn More →Ductless Mini Split
An outdoor compressor connects to one or more indoor wall-mounted units — no ductwork required. Each indoor unit controls its own zone. Highly energy-efficient and ideal for spaces without ducts.
Best for: NYC apartments, brownstones, additions, and rooms without ductwork.
Learn More →Boiler & Radiator System
Boilers heat water and distribute it through pipes to radiators, baseboard heaters, or radiant floor systems. Very common in older NYC buildings. Provides heating only — a separate AC system is needed for cooling.
Best for: Pre-war apartments and brownstones with existing radiator infrastructure.
Learn More →Furnace (Forced Air)
Burns fuel (gas, oil, or propane) or uses electricity to heat air, then distributes it through ductwork. Often paired with a central AC condenser for year-round climate control.
Best for: Houses with ductwork, especially in suburban areas.
Learn More →Heat Pump
Uses electricity to transfer heat rather than generate it — heating in winter and cooling in summer from one unit. Available as air source (most common), geothermal (most efficient), and hybrid models.
Best for: Energy-conscious homeowners. Significant tax credits available.
Learn More →VRF / VRV System
Variable Refrigerant Flow systems provide individual zone control for multi-room or multi-story buildings. Can heat some zones while cooling others simultaneously. Extremely energy-efficient.
Best for: Commercial buildings, offices, hotels, and high-end residential.
Learn More →Rooftop Unit (RTU)
All-in-one packaged units installed on commercial rooftops. Handles heating, cooling, and ventilation in a single cabinet. Common on retail stores, restaurants, and warehouses.
Best for: Commercial spaces with flat roofs.
Learn More →ERV (Energy Recovery Ventilator)
Exchanges stale indoor air with fresh outdoor air while recovering energy (heat or coolness) from the exhaust. Improves air quality without wasting energy. Often paired with existing HVAC systems.
Best for: Tight buildings needing better air quality — offices, healthcare, schools.
Learn More →How HVAC Systems Work
At a high level, most HVAC systems work on the same basic principles:
Thermostat Signals
When the temperature drifts from your thermostat setting, it sends a signal to your HVAC system to start heating or cooling. Smart thermostats can learn your patterns and optimize automatically.
Heat Exchange
For cooling: Refrigerant absorbs heat from indoor air at the evaporator coil, then releases it outside at the condenser coil. For heating: A furnace burns fuel to heat air, a boiler heats water, or a heat pump reverses the refrigeration cycle to bring heat indoors.
Air Distribution
Conditioned air is pushed through ductwork by a blower fan (ducted systems) or blown directly into the room (ductless systems). Hot water systems use pumps to circulate heated water to radiators.
Filtration & Ventilation
Air passes through filters that trap dust, allergens, and particles. Ventilation systems (like ERVs) bring in fresh air while exhausting stale air, maintaining healthy indoor air quality.
Cycle Completes
Once the desired temperature is reached, the thermostat signals the system to stop. The system cycles on and off to maintain the set temperature. Efficiency is measured by how little energy each cycle uses.
HVAC Maintenance: What Every Homeowner Should Know
Regular maintenance is the single best way to extend your system's life, prevent breakdowns, and keep energy costs low. Here's what you can do:
Change Filters Regularly
Replace standard 1-inch filters every 1-3 months. This is the easiest and most impactful thing you can do. A dirty filter restricts airflow, makes your system work harder, and can increase energy bills by 15%.
Keep the Outdoor Unit Clear
Remove leaves, debris, and vegetation from around your outdoor AC or heat pump condenser. Maintain at least 2 feet of clearance for proper airflow.
Don't Block Vents & Registers
Keep furniture, curtains, and rugs away from supply and return vents. Blocked vents cause pressure imbalances that reduce efficiency and can damage your system.
Schedule Professional Tune-Ups
Have your system professionally serviced at least once a year — ideally twice (spring for AC, fall for heating). A technician catches issues before they become expensive repairs.
Listen for Unusual Sounds
Grinding, squealing, banging, or clicking sounds are warning signs. Shut the system off and call a professional before a small issue causes major damage.
Check Your Thermostat
Make sure your thermostat is set correctly and responding to changes. Consider upgrading to a programmable or smart thermostat — it can save 10% or more on energy costs annually.
Understanding HVAC Energy Efficiency
Energy efficiency directly impacts your utility bills and environmental footprint. Here are the key ratings to know when shopping for HVAC equipment:
SEER / SEER2 (Cooling)
Seasonal Energy Efficiency Ratio measures cooling efficiency. Higher is better. The federal minimum is SEER2 14.3 (as of 2023). High-efficiency units reach SEER2 20+. Going from SEER 10 to SEER 16 can cut cooling costs by 40%.
AFUE (Heating — Furnaces & Boilers)
Annual Fuel Utilization Efficiency measures how much fuel becomes usable heat. A 95% AFUE furnace converts 95 cents of every fuel dollar into heat. High-efficiency condensing units reach 97-98% AFUE.
HSPF / HSPF2 (Heat Pumps)
Heating Seasonal Performance Factor measures heat pump heating efficiency. Higher is better. HSPF2 8.0+ is considered high efficiency. Heat pumps with high HSPF ratings are eligible for federal tax credits.
ENERGY STAR
Look for the ENERGY STAR label — it means the equipment meets or exceeds EPA efficiency standards. ENERGY STAR HVAC systems use 15-20% less energy than standard models and often qualify for rebates.
Not sure which efficiency level is right for your budget and goals? We can help you find the sweet spot between upfront cost and long-term savings. Request a free estimate or use our Portfolio to determine what size system you need.
Find Your Perfect System Size
Use our free BTU Calculator to determine exactly how much heating and cooling power your space needs.
Try the BTU Calculator →Need Expert HVAC Help?
Whether you need installation, repair, or maintenance — Fixar has you covered across NYC.
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