Have you ever looked at an HVAC repair invoice and felt like it was written in another language? You’re not alone. Understanding common HVAC terms can help you feel more confident when discussing your system with a technician—and protect you from companies that use misleading jargon to upsell their services.
Here’s a breakdown of key HVAC terms every homeowner should know, plus a few “creative” terms some companies use to make simple parts sound more complicated (and expensive) than they really are.
1. Air Handler
The air handler is the indoor portion of an HVAC system that moves conditioned air through your home. While a gas furnace technically acts as an air handler because it contains a fan, the term almost always refers to the indoor unit of a heat pump or electric system. This unit contains the evaporator coil, electric heat strips, and blower—all critical components for heating and cooling your home.
2. Condensing Unit
Though some refer to this as the “air conditioner”, the condensing unit is the outdoor portion of your air conditioning system. People often mistakenly call it the “compressor”, which is the motor inside the condensing unit that’s responsible for circulating refrigerant. If you have a heat pump system, the outdoor portion of your system is often referred to as a “heat pump” or “heat pump condenser”.
3. SEER2 Rating (Seasonal Energy Efficiency Ratio)
A SEER2 rating is the measure of energy efficiency of an air conditioning system over an entire cooling season. The higher the number, the more energy-efficient the unit. In Texas, manufacturers are required to supply all systems with a minimum SEER2 rating of 13.8 or higher–this will help keep energy bills manageable without sacrificing comfort. In 2024 the standards for measuring energy efficiency in HVAC units changed, and with it changed the name from SEER or SEER2, although they are essentially the same rating.
4. MERV Rating (Minimum Efficiency Reporting Value)
MERV ratings apply to air filters and indicate their ability to trap airborne particles. A higher MERV rating means better filtration, which can help reduce allergens—a big plus for San Antonio residents who battle seasonal allergies. However, filters with extremely high MERV ratings can restrict airflow, so choosing the right one for your system is essential. Typically MERV 6 is the lowest rating that should be used, while MERV 13 is a heavy duty filter. For most systems, MERV 9 is a good filter that will not restrict airflow.
5. Zoning System/Damper System
A zoning system divides your home into different climate zones, each with their own thermostat, allowing for more precise temperature control. If you live in a home that has multiple stories, rooms with high ceilings, rooms with lots of natural sunlight, zoning systems can be a game-changer by directing airflow where it’s needed most.
6. Heat Exchanger
A heat exchanger is a device designed to transfer heat between two mediums while keeping them separate.
- When heating, heat exchangers in your furnace transfer heat from combustion gases pushed through it to the air before it’s dispersed in your home, ensuring the gases remain contained and are safely vented. As the heat exchanger heats up and cools down, it repeatedly expands and contracts. Over time, this consistent stress can lead to cracks, a serious issue that can lead to dangerous carbon monoxide leaks and pose serious health risks.
- When cooling, the evaporator and condenser coils act as heat exchangers–though they’ll almost always be referred to by their specific name. The evaporator coil allows refrigerant to absorb the heat from the air coming into the home to cool it. The refrigerant then flows through the condenser coil where the absorbed heat is released outside your home.
Misleading HVAC Terminology: What to Watch For
Some companies use overcomplicated language to make common components seem more sophisticated than they really are. Here are a few terms we’ve seen on invoices that might raise red flags and what they really mean:
- “Dual Voltage Battery Cap” = Capacitor: an electrical component responsible for providing the power necessary to start the compressor motor.
- “High Voltage Distribution System” = Contactor: a device used to switch the electric circuit on and off.
- “Indoor/Outdoor Air Drive System” = Fan Motor: the component that powers the fan that moves air in and out of the home.
If a company presents a confusing term, don’t be afraid to ask for clarification—or better yet, get a second opinion.
Knowledge = Power (and Savings!)
Being informed about HVAC terminology helps you make smarter decisions about your system and avoid unnecessary expenses. Whether you’re scheduling maintenance, repairing a unit, or upgrading your system, understanding these terms ensures you’re in control.
At North East Air Conditioning, Heating & Plumbing, we believe in honest, transparent service—no gimmicks, no sales tricks, just straightforward solutions to keep your home comfortable. So whatever your system may need, we’re here to help.
