Reference
HVAC, Plumbing & IAQ Glossary
The terms you'll see on quotes and invoices, in plain language — so nothing on an estimate catches you off guard.
Written by the Anna's Air, Heat & Plumbing teamReviewed by [GATHER: named licensed HVAC/plumbing reviewer + role for author attribution]Last updated
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Air conditioning & cooling
- SEER2
- Seasonal Energy Efficiency Ratio 2 — the current rating for how efficiently a system cools over a season. Higher SEER2 means lower cooling bills. Learn more .
- Ton / tonnage
- A measure of cooling capacity. One ton equals 12,000 BTU per hour of cooling. Homes are matched to the right tonnage during a load calculation.
- BTU
- British Thermal Unit — a unit of heat energy. HVAC capacity is often expressed in BTU per hour.
- Compressor
- The pump in the outdoor unit that pressurizes and circulates refrigerant. It's the most expensive single component, so a failed compressor often tips the repair-or-replace decision. Learn more .
- Condenser (outdoor unit)
- The outdoor part of a split system that releases heat collected from inside your home. Salt air on the barrier islands is hard on condenser coils.
- Evaporator coil
- The indoor coil that absorbs heat and moisture from your home's air. A frozen or leaking evaporator coil is a common AC problem.
- Air handler
- The indoor unit that houses the blower and evaporator coil and moves conditioned air through your ducts.
- Refrigerant
- The fluid that carries heat through the system. Modern units use low-GWP refrigerants like R-454B or R-32; older units use R-410A or R-22.
- R-22
- An older refrigerant no longer produced in the U.S. Recharging an R-22 system is increasingly costly, which often favors replacement. Learn more .
- Capacitor
- A small electrical component that helps start and run the motors and compressor. A failed capacitor is one of the most common — and affordable — AC repairs.
- Short cycling
- When a system turns on and off too frequently. It wastes energy, wears parts, and signals a problem such as an oversized unit, low refrigerant, or a thermostat issue.
Heating & heat pumps
- Heat pump
- A system that moves heat instead of generating it, and reverses to both heat and cool a home. It's the most common heating system in Florida. Learn more .
- HSPF2
- Heating Seasonal Performance Factor 2 — the current rating for a heat pump's heating efficiency. Higher is more efficient.
- Reversing valve
- The component that lets a heat pump switch between cooling and heating by changing the direction the refrigerant flows. Learn more .
- Auxiliary / emergency heat
- Electric backup heat. 'AUX' assists the heat pump in cold weather; 'EM' runs the backup alone if the heat pump fails. Both use more electricity. Learn more .
- Heat strips
- Electric-resistance heating elements in the air handler that provide auxiliary or backup heat.
- Furnace
- A heating-only system that burns gas or uses electric elements to create heat. Common in cold climates, uncommon in Florida. Learn more .
- Dual-fuel / hybrid system
- A heat pump paired with a gas furnace for backup in very cold weather. Mostly a cold-climate solution, rarely needed on the Space Coast.
Water heaters & plumbing
- Storage tank water heater
- A water heater that keeps a 40–50+ gallon reservoir hot and ready. Lower up-front cost; typically lasts 8–12 years. Learn more .
- Tankless (on-demand) water heater
- A unit that heats water only as it flows, so it never runs out — but is limited by flow rate. Typically lasts 15–20 years with maintenance. Learn more .
- Anode rod
- A sacrificial metal rod inside a tank water heater that corrodes in place of the tank. Replacing it on time extends the tank's life. Learn more .
- Sediment
- Minerals from hard water that settle in a tank, causing popping noises, lost efficiency, and faster corrosion. An annual flush helps.
- Hard water
- Water with a high mineral content, common in Florida. It builds scale on fixtures, in pipes, and inside water heaters. Learn more .
- Water softener
- A system that reduces water hardness, protecting plumbing, appliances, and water heaters from scale buildup.
- Slab leak
- A leak in a water line beneath a home's concrete slab. Signs include high bills, warm floor spots, and the sound of running water — it needs professional detection. Learn more .
- Repiping
- Replacing a home's failing supply pipes with modern materials, considered when leaks, corrosion, or low pressure recur.
- GPM (gallons per minute)
- A flow-rate measure. For tankless water heaters, GPM determines how many fixtures can run hot water at the same time.
- Pressure regulator
- A valve that controls the water pressure entering your home. A failing regulator can cause pressure that's too high or too low.
Indoor air quality
- Indoor air quality (IAQ)
- The condition of the air inside your home — temperature, humidity, and pollutants like dust, allergens, and mold spores.
- MERV rating
- Minimum Efficiency Reporting Value — how well an air filter captures particles. Higher MERV traps smaller particles, but must match what your system can handle.
- HEPA
- High-Efficiency Particulate Air filtration — a very high standard of particle capture, used in dedicated air-purification equipment.
- UV germicidal light
- An ultraviolet light installed in the air handler to reduce mold and microbes on the coil and in the air stream — useful in humid Florida systems.
- Dehumidification
- Removing moisture from indoor air. A correctly sized AC dehumidifies as it cools; whole-home dehumidifiers add capacity in humid climates.
- Duct sealing
- Closing leaks in ductwork so conditioned air reaches your rooms instead of escaping into attics or walls — a common efficiency and comfort fix.
Permits, code & general terms
- Permit
- Authorization from your local building department to perform certain work, such as an HVAC changeout or water heater replacement, followed by an inspection. Learn more .
- AHJ (Authority Having Jurisdiction)
- The local agency — usually a city or county building department — that issues permits and inspects work. Brevard County has several, depending on your address. Learn more .
- Florida Building Code (FBC)
- The statewide code that governs construction and mechanical, plumbing, and electrical work in Florida, enforced locally by each AHJ. Learn more .
- Load calculation (Manual J)
- The industry method for sizing an HVAC system to a specific home, based on its size, insulation, windows, and climate — so the system isn't too big or too small.
- 365-Day Money-Back Guarantee
- Anna's promise standing behind our work for a full year — part of our no-pressure, customer-first approach.
Put these terms to work
Read the guides where these terms come up most.
Still have a question about a term on your quote?
Ask Anna's — our woman-owned team is happy to explain anything on an estimate in plain English, with no pressure to buy.