Every HVAC term, plain-English first.

A

ACCA Manual D

Ducts & Distribution

ACCA Manual D is the residential duct-design methodology — the companion to Manual J — that calculates duct sizing, layout, fittings, and total external static pressure to deliver each room its Manual-J-calculated airflow at the air handler's rated external static pressure. Manual D outputs a trunk-and-branch design with friction-rate-based duct sizes, equivalent-length penalties for every elbow and fitting, and balancing damper locations. A correct Manual D pairs with the chosen blower's airflow curve and the chosen filter's pressure drop. Skipping Manual D is the leading reason high-SEER2 equipment fails to deliver its rated efficiency in practice.

Why it matters in South Louisiana

South Louisiana attic duct systems are routinely undersized because they were installed in the 1990s and 2000s alongside lower-SEER equipment with louder, more aggressive blowers. Drop a modern variable-speed air handler into that same duct envelope and total external static pressure jumps past 0.8 in. W.C., killing efficiency and shortening blower life. Cypress Cooling's replacement quotes include a duct-sizing review against Manual D before any equipment is recommended.

See also:static pressure·Manual J load calculation·ductwork 101

ACCA Manual J

Ducts & Distribution

ACCA Manual J is the residential heating-and-cooling load calculation that determines correct equipment size.

ACCA Manual J is the Air Conditioning Contractors of America's published residential heating and cooling load calculation methodology, used to determine the actual heat gain and heat loss of a specific home — and therefore the correct equipment size in BTU/h. A Manual J considers building envelope (walls, ceilings, floors, windows, doors), insulation R-values, infiltration rate, internal gains (occupants, lighting, appliances), latent load from moisture infiltration, and design temperatures keyed to the home's location. A complete Manual J is room-by-room (Block J is whole-house). It replaces square-footage rules of thumb, which routinely oversize equipment in the South. ACCA Manual J is required by most building codes for new construction.

Why it matters in South Louisiana

Manual J is the difference between a 2.5-ton system that runs long and dries out a Mid-City house and an oversized 3.5-ton system that short-cycles, leaves humidity at 65%, and shortens its own compressor life. Honest Louisiana contractors run a Manual J — including latent-load math for the region's high outdoor dew points — before quoting a replacement. Anyone who quotes by “tonnage per 500 square feet” is guessing.

See also:ACCA Manual D duct design·ACCA Manual S equipment selection·repair vs replace framework

ACCA Manual S

Ducts & Distribution

ACCA Manual S is the equipment-selection methodology that takes the loads produced by Manual J and matches them to a specific manufacturer's published performance data at the local design conditions. It looks at sensible cooling capacity (at the actual local outdoor dry bulb and indoor wet bulb — not the standard 95°F/80°F nameplate rating), latent cooling capacity (which determines real humidity-removal performance), heating capacity at the local design temperature, and airflow at the planned external static pressure. Manual S accounts for capacity derating in real climates and is what separates “we picked a 3-ton because the old one was a 3-ton” from a defensible engineering choice.

Why it matters in South Louisiana

At Louisiana's hot-and-humid design point, nameplate cooling capacity drops several percent and latent capacity shifts significantly relative to the 95°F/80°F lab condition. Without a Manual S pass, two systems with identical nameplate tonnage can perform very differently in a Metairie summer. That's why a Manual J without Manual S is half a design — and why Cypress Cooling references both in every replacement proposal.

See also:Manual J load calculation·Manual D duct design·repair vs replace framework

ACH (Air Changes per Hour)

Indoor Air Quality

ACH (Air Changes per Hour) is the number of times the entire volume of air in a space is replaced over one hour. In residential HVAC it appears in two forms. ACH-natural describes how leaky a building shell is to outside air, often measured indirectly through ACH50 — air changes per hour at 50 pascals of pressure during a blower-door test. Typical existing-construction ACH50 lands between 7 and 20; high-performance retrofits target 3 or lower. ACH-mechanical describes intentional ventilation — how many room-volumes per hour an ERV, HRV, or exhaust system delivers. ASHRAE 62.2 sets the residential ventilation minimum.

Why it matters in South Louisiana

Older South Louisiana housing stock — pier-foundation shotguns, balloon-framed two-stories, and pre-1980 ranch homes — typically tests in the ACH50 12–18 range, meaning the HVAC is fighting an enormous unintentional infiltration of hot, humid outdoor air all summer. Tightening the shell drops humidity load, drops cooling load, and lets right-sized equipment actually do its job. Blower-door ACH testing belongs on every weatherization assessment in the Greater New Orleans area.

See also:static pressure·humidity in Louisiana homes·indoor air quality service

AFUE

Heating

AFUE is the seasonal efficiency percentage for gas, oil, or propane furnaces.

AFUE (Annual Fuel Utilization Efficiency) is the U.S. Department of Energy's seasonal efficiency rating for gas, oil, and propane furnaces. It expresses how much of the fuel's chemical energy a furnace converts into delivered heat over a typical heating season, after accounting for cycling, standby, and flue losses. AFUE is reported as a percentage: an 80% AFUE furnace converts 80 cents of every fuel dollar into usable heat; a 96% condensing furnace converts 96 cents. Residential gas furnaces split into non-condensing (80% AFUE, single-vent) and condensing (90–98% AFUE, dual PVC vent and condensate drain). AFUE does not measure electrical consumption (blower watts) — that's a separate consideration.

Why it matters in South Louisiana

South Louisiana's heating season is short — typically only 30–45 days of meaningful furnace runtime — so the payback math on jumping from 80% to 96% AFUE is much slower here than in the Midwest. For most Metairie or Westwego homes, the heat-pump-versus-gas-furnace decision matters more than chasing AFUE percentage points. AFUE matters most for homes that already burn substantial gas, like older two-story Garden District properties.

See also:HSPF2 heat-pump efficiency·heat pump vs gas furnace in South Louisiana·heating service

B

Balance Point

Heating

Balance point is the outdoor temperature where a heat pump exactly meets the building's heat loss.

The balance point is the outdoor temperature at which a heat pump's heating capacity exactly matches the building's heat-loss rate. Above the balance point, the heat pump alone meets the heating load; below it, the heat pump cannot keep up and a supplemental heat source (electric resistance strips, a gas furnace in a dual-fuel system, or higher-stage operation in an inverter system) must engage. Balance point is calculated by overlaying a manufacturer's capacity-vs.-outdoor-temperature curve onto the building's Manual J load curve. A 3-ton single-speed heat pump in a tightly built 1,900 sq ft Mandeville home might balance around 35°F outdoor; an inverter unit in the same home might balance below 25°F.

Why it matters in South Louisiana

South Louisiana's design temperature sits roughly 27–32°F depending on parish, which means most properly sized heat pumps balance near or below that point — supplemental heat fires only during genuine cold snaps. Knowing the balance point is what separates “heat pump won't keep up” complaints (usually a sizing or control-strategy issue) from real comfort problems. A correct balance-point calc is part of every heat-pump-versus-gas-furnace conversation Cypress Cooling has.

See also:COP at varying outdoor temperatures·dual-fuel system·heat pump vs gas furnace in South Louisiana

BTU/h

Cooling

BTU/h measures how much heat an HVAC system can move per hour; 12,000 BTU/h equals one ton.

BTU/h (British Thermal Units per hour) is the unit used to describe the heating or cooling capacity of an HVAC system — how much heat it can move out of (or into) a home per hour. One BTU is the energy needed to raise one pound of water by 1°F; 12,000 BTU/h equals one “ton” of cooling. A typical Louisiana single-family home needs 24,000–60,000 BTU/h (2 to 5 tons) of cooling capacity depending on square footage, ceiling height, insulation, window load, and air-tightness. The correct BTU/h target comes from an ACCA Manual J load calculation — never from a square-footage rule of thumb.

Why it matters in South Louisiana

Oversizing is the single most common HVAC sin in the Greater New Orleans market. A 5-ton condenser stuffed into a 1,800-square-foot Mid-City shotgun cools the air faster than it can dehumidify it, leaving the home cold and clammy. Manual-J-correct BTU/h sizing trims runtime, removes more moisture from the air, and stretches equipment life — especially important here, where summer runtime is brutal.

See also:ACCA Manual J load calculation·humidity in Louisiana homes·air conditioning service

C

CADR

Indoor Air Quality

CADR (Clean Air Delivery Rate) is the AHAM-standardized performance rating for portable room air cleaners, reported in cubic feet per minute for three particle sizes: smoke, dust, and pollen. CADR equals the effective volume of contaminant-free air a unit delivers per minute. AHAM's 2/3 rule recommends sizing a portable air cleaner so its smoke CADR is at least two-thirds of the room area in square feet. Unlike MERV, CADR is a system-level rating — it folds together filter efficiency, airflow, and bypass losses — and is the right metric when comparing portable air cleaners head-to-head. It does not apply to whole-home in-duct filters.

Why it matters in South Louisiana

Portable HEPA cleaners with strong CADR ratings make sense in bedrooms during wildfire-smoke episodes, in remediation rooms after a flood event, or in pet-heavy homes where the central system can't be upgraded to MERV 13. They are not a substitute for proper central filtration and dehumidification in the Greater New Orleans market — but they're useful as a layered supplement when the central system has reached its filtration ceiling.

See also:MERV in-duct filter rating·humidity in Louisiana homes·indoor air quality service

Compressor Types (Scroll / Rotary / Inverter)

Cooling

Residential air conditioners and heat pumps use one of three compressor families. Scroll compressors use two intermeshing orbiting spirals and are the dominant single-stage and two-stage residential design — quiet, efficient, and tolerant of liquid slugging. Rotary compressors (rolling-piston or twin-rotary) are compact and common in mini-split and small-tonnage equipment. Inverter-driven compressors (always scroll or rotary, paired with variable-frequency-drive electronics) modulate motor speed continuously between roughly 30% and 110% of nameplate capacity instead of cycling on and off — yielding the highest SEER2/EER, the tightest temperature swings, and the best latent (humidity) removal. Each type wears differently and is diagnosed and serviced differently.

Why it matters in South Louisiana

Inverter-driven systems shine in South Louisiana because they spend most of the summer at a low, steady speed — pulling humidity out of the air for hours at a time rather than slamming on and off. That's the difference between a Slidell living room that feels cool-and-dry at 75°F and one that feels clammy-cool at 72°F. The tradeoff: inverter electronics are sensitive to dirty filters, voltage sags during thunderstorms, and corroded outdoor boards from coastal salt air.

See also:SEER2 efficiency rating·ductless mini-split vs central air·ductless mini-split installation

Condenser Coil

Cooling

The condenser coil is the outdoor heat-exchange coil where hot, high-pressure refrigerant vapor leaving the compressor releases its heat to the outdoor air and condenses into a liquid. It is built from copper or aluminum tubing and aluminum fins, with a fan pulling air across the surface. Condenser coil cleanliness directly drives high-side pressures: a coil clogged with cottonwood seed, lint, or pet hair forces the compressor to work against artificially high head pressure, dropping efficiency and accelerating compressor wear. The condenser coil is also the corrosion-prone half of the refrigerant circuit in coastal climates because it sits outdoors year-round.

Why it matters in South Louisiana

Salt air from Lake Pontchartrain, the Mississippi River, and the Gulf attacks aluminum condenser fins and copper tubing — homes within a few miles of open water can see formicary corrosion (pinhole leaks) on a 6- to 8-year-old coil that would last 15 years inland. Annual coil rinsing with a non-acid cleaner and a factory-coated coil option at install time are the two highest-leverage maintenance moves for Mandeville, Bucktown, and Algiers homeowners.

See also:evaporator coil (indoor side)·subcooling measurement·air conditioning service

COP (Coefficient of Performance)

Heating

COP (Coefficient of Performance) is the instantaneous efficiency ratio of a heat pump or refrigeration system at a specific operating point: heat output (in watts of thermal energy) divided by electrical input (in watts of electrical energy). COP is dimensionless. A COP of 3.0 means the system delivers 3 watts of heat for every 1 watt of electricity consumed — the other 2 watts come from heat extracted from outdoor air. COP varies with outdoor temperature: a typical residential heat pump runs COP 3.5–4.5 at 47°F outdoor, drops to 2.5–3.0 at 17°F outdoor, and approaches 1.0 (resistance-heat equivalent) at very cold extremes. HSPF2 is roughly a season-averaged COP.

Why it matters in South Louisiana

South Louisiana's climate keeps heat pumps in their high-COP sweet spot for nearly the entire heating season. Even during cold-snap weeks where Metairie or Slidell sees overnight lows in the upper 20s°F, a modern inverter heat pump stays at COP 2.8 or better — meaning electric resistance strips kick in rarely and only briefly. That's the math behind why properly sized heat pumps now compete head-to-head with gas in this market.

See also:HSPF2 seasonal heat-pump rating·balance point·heat pump service

D

Defrost Cycle

Heating

A defrost cycle is a heat-pump operating mode that periodically melts frost off the outdoor coil during heating operation. In heat mode, the outdoor coil acts as an evaporator — running below ambient and below freezing — and condenses moisture from the air. When the surface drops below 32°F and humidity is high, that moisture freezes onto the coil, blocking airflow and dropping capacity. The control board reverses the refrigerant flow (the unit briefly runs in cooling mode), shuts off the outdoor fan, and energizes electric strips to temper the supply air. Defrost typically lasts 4–10 minutes and triggers on time, demand, or hybrid logic. Brief steam rising from the outdoor unit is normal.

Why it matters in South Louisiana

South Louisiana's humid winter cold snaps produce some of the most aggressive defrost behavior heat pumps will ever see — a 38°F drizzly morning in Covington can frost a coil faster than a 22°F dry morning in Tennessee. Homeowners often mistake the resulting steam plume for a unit on fire. Defrost cycles that run too often (every 30 minutes or less) usually point to a low-charge issue, a stuck reversing valve, or a dirty outdoor coil — common in homes near oak-leaf fall.

See also:compressor types·balance point·heat pump service

Dehumidification Ratio

Indoor Air Quality

Dehumidification ratio describes how much of an AC's cooling capacity removes moisture versus temperature.

Dehumidification ratio is the share of an air conditioner's total cooling capacity that goes to removing moisture (latent cooling) rather than dropping air temperature (sensible cooling). It is typically expressed via the sensible heat ratio (SHR): a system with an SHR of 0.75 spends 75% of its capacity on sensible cooling and 25% on latent; an SHR of 0.65 spends 65% on sensible and 35% on latent — a “wet coil” profile preferred in humid climates. A lower SHR means better moisture removal at any given thermostat setting. Variable-speed equipment, slower indoor blower speeds, and lower fin density on the evaporator all shift SHR toward better dehumidification.

Why it matters in South Louisiana

Louisiana summers run 70–85% relative humidity outdoors — meaning a properly designed AC must spend more capacity on dehumidification than equipment selected for, say, Phoenix. A system with the wrong dehumidification ratio “cools” a Carrollton bedroom to 72°F and still feels sticky, because the AC removed degrees but not moisture. Cypress Cooling specs equipment with low-SHR profiles, variable-speed blowers, and (when needed) a dedicated whole-home dehumidifier to actually hold indoor humidity in the 45–55% target range.

See also:evaporator coil·whole-home vs standalone dehumidifier·humidity in Louisiana homes

Dual-Fuel System

Heating

A dual-fuel system (also called a hybrid system) pairs an electric heat pump with a gas furnace under a single thermostat. The control logic uses the heat pump for cooling and for primary heat at moderate outdoor temperatures; when outdoor temperature drops below a programmable switchover setpoint — typically the system's balance point or the breakeven point where gas becomes cheaper to operate than electricity — the heat pump locks out and the gas furnace takes over. Dual-fuel systems eliminate the need for electric resistance backup, reduce peak electrical load on the coldest mornings, and shift the heating fuel decision to current utility prices.

Why it matters in South Louisiana

Dual-fuel makes the most sense for South Louisiana homes that already have natural gas service and a relatively recent furnace. The heat pump handles 95%+ of the heating season at high COP, while the gas furnace covers the 5–10 cold-snap days a year when outdoor temperatures dip into the low 20s. For Metairie homeowners with a working 80% AFUE furnace and an aging condenser, swapping the condenser for a heat pump and going dual-fuel is often the lowest-disruption path to lower bills.

See also:balance point·AFUE furnace efficiency·heat pump vs gas furnace in South Louisiana

E

EER

Cooling

EER (Energy Efficiency Ratio) is the steady-state cooling-efficiency rating measured at a fixed 95°F outdoor / 80°F indoor / 50% indoor humidity test point. Where SEER2 averages efficiency across a simulated cooling season, EER reports performance at one peak-hot moment — making it the more honest metric for hot, humid climates like the Gulf Coast. EER is expressed as cooling output (BTU/h) divided by power input (W). High-efficiency residential systems land in the 11–13 EER range, while commercial rooftop units publish EER directly. The newer EER2 variant uses the M1 test procedure (lower external static pressure) and applies to equipment rated after January 2023.

Why it matters in South Louisiana

South Louisiana is hot and humid almost six months of the year, so peak-hour AC behavior matters more than seasonal averaging. EER is the rating to ask about when comparing systems for a home in Hammond, Slidell, or Mid-City that runs the AC essentially nonstop from May through September. A 13-EER system handles a 96°F afternoon noticeably better than an 11-EER system with the same SEER2 sticker.

See also:SEER2 seasonal efficiency rating·BTU/h capacity unit·air conditioning service

Evaporator Coil

Cooling

The evaporator coil is the indoor heat-exchange coil where low-pressure liquid refrigerant absorbs heat from return air and boils into a vapor. It is the cold side of the refrigerant circuit and the place where atmospheric moisture condenses out of the air stream into the drain pan — which is why a properly performing evaporator coil produces a noticeable water flow at the condensate line during humid weather. Evaporator coils come in A-coil, N-coil, or slab configurations and live in the air handler or above a gas furnace. Airflow restrictions, low refrigerant charge, or a stuck metering device will let coils ice over and lose capacity.

Why it matters in South Louisiana

In Louisiana, the evaporator coil is the unsung hero of humidity control. A coil that's properly sized, clean, and matched to a correctly tuned blower will pull 10–15 gallons of water out of a New Orleans home on a wet summer day. A coil that's oversized, dirty, or paired with a too-fast blower short-cycles the compressor and leaves moisture behind — which is why so many “cold but sticky” homes are coil/blower mismatches, not refrigerant problems.

See also:condenser coil (outdoor side)·dehumidification ratio·humidity in Louisiana homes

F

Furnace Stages (Single / Two / Modulating)

Heating

Residential gas furnaces fire in one of three control patterns. Single-stage furnaces have one fixed firing rate — full output or off — and are simplest, cheapest, and least comfortable. Two-stage furnaces switch between a low firing rate (about 65–70% of nameplate) and high, spending most mild-weather runtime on low for quieter, longer cycles. Modulating (or fully variable) furnaces continuously trim firing rate between roughly 40% and 100% of nameplate using a variable gas valve and inducer motor, paired with a variable-speed ECM blower. Modulating units deliver the tightest temperature swings, the longest runtimes, and the best AFUE realization — at significantly higher equipment and install cost.

Why it matters in South Louisiana

Because Louisiana's heating season is so short, the comfort gap between single-stage and modulating furnaces is felt most during shoulder-season mornings — November and February — when a single-stage roars on, blows the room past setpoint, then shuts off. In that climate, a two-stage furnace is the practical sweet spot for cost vs. comfort; a modulating furnace pays off only in larger or two-story homes where temperature stratification is already a problem.

See also:AFUE seasonal efficiency·heat pump vs gas furnace in South Louisiana·heating service

H

HSPF2

Heating

HSPF2 is the current DOE seasonal heat-pump heating-efficiency rating, replacing HSPF as of 2023.

HSPF2 (Heating Seasonal Performance Factor 2) is the standardized heating-mode seasonal efficiency rating for residential heat pumps in the United States, updated under the M1 test procedure that took effect January 1, 2023. It expresses total heating output (BTU) divided by electricity consumed (W-hours) across a simulated heating season. HSPF2 typically reads 8–15% lower than legacy HSPF for the exact same equipment because the new test uses a more realistic 0.5 in. W.C. external static pressure load. Current minimum residential HSPF2 in the Southeast region is 7.5, with mid-tier units in the 8.1–9.5 range and best-in-class variable-speed heat pumps reaching 10.0+.

Why it matters in South Louisiana

HSPF2 matters more in South Louisiana than most homeowners realize. A heat pump is a viable primary heating source in Metairie, New Orleans, and the Northshore because design temperatures rarely fall below the mid-20s°F — well within heat-pump efficient operating range. A modern HSPF2 8.5+ inverter heat pump beats resistance strip heat and rivals an 80% AFUE gas furnace on operating cost in the Cleco and Entergy rate environment.

See also:COP instantaneous efficiency·heat-pump balance point·heat pump vs gas furnace in South Louisiana

M

Mastic vs Tape Sealing

Ducts & Distribution

Mastic and tape are the two common materials for sealing residential duct joints and seams. Duct mastic is a brush- or trowel-applied water-based, fibrous-reinforced sealant that cures into a hard, flexible coating with a service life that effectively matches the duct. UL 181-rated foil tape is a pressure-sensitive aluminum-faced tape that adheres to clean, primed sheet metal and holds for years in conditioned space — but loses adhesive in attic temperature cycling and cannot reliably seal flex-duct connections. Mastic is the field standard for permanent, code-compliant duct sealing under IECC and IRC. Cloth-fabric “duct tape” fails within months and is not code-acceptable for HVAC duct sealing.

Why it matters in South Louisiana

An unconditioned New Orleans attic reaches 130–145°F on summer afternoons. Foil tape applied to flex-duct collars at install fails within two to four years under that temperature cycling, opening leak paths that dump 15–30% of conditioned air into the attic. Re-sealing those joints with mastic is one of the highest-ROI retrofits in Greater New Orleans homes — cheaper than new equipment and often saving meaningful kWh on the next Entergy bill.

See also:static pressure·return air·ductwork 101

MERV

Indoor Air Quality

MERV is the ASHRAE 1–16 rating of a filter's particle-capture efficiency.

MERV (Minimum Efficiency Reporting Value) is the ASHRAE 52.2 standardized filter-effectiveness rating, on a 1-to-16 scale for residential and light-commercial filters. Higher MERV captures smaller particles: MERV 6–8 stops pollen, dust mites, and large lint; MERV 11–13 captures finer dust, mold spores, and some bacteria; MERV 13+ captures most respirable particles, including many viruses. MERV is measured at a defined face velocity — pushing higher-MERV media through a system designed for low-MERV creates excessive static pressure that drops airflow, ices coils, and stresses blowers. The right MERV is the highest the system can move air through without breaking design static pressure — usually 8–13 for a residential ducted system with 1-inch filters, up to 16 for a deep-pleat media cabinet.

Why it matters in South Louisiana

New Orleans, Mandeville, and Hammond homes face a real IAQ load — mold spores, allergens from year-round vegetation, post-flood drywall dust, and HEPA-defeating cooking aerosols. Jumping a 1-inch return filter from MERV 8 to MERV 13 without checking static pressure is one of the most common causes of “AC doesn't cool right anymore” calls. A 4- or 5-inch media cabinet at the air handler is usually the better path for high MERV here.

See also:static pressure·CADR portable air-cleaner rating·indoor air quality service

R

R-22

Cooling

R-22 (chlorodifluoromethane, also called HCFC-22 or Freon™) is the refrigerant used in most residential air conditioners manufactured before 2010. The U.S. Environmental Protection Agency phased out R-22 under the Montreal Protocol because it depletes the ozone layer: new equipment charged with R-22 was banned in 2010, and production and import of virgin R-22 stopped on January 1, 2020. Existing R-22 systems can still be serviced, but any added refrigerant must come from reclaimed or recovered stock — driving per-pound prices far above modern alternatives. Most homeowners discovering an R-22 leak today are choosing between an expensive partial repair and a full replacement to R-410A or one of the new A2L refrigerants.

Why it matters in South Louisiana

Plenty of homes in older Uptown, Algiers Point, Carrollton, and the Northshore still operate 15- to 20-year-old R-22 condensers. When one of those systems develops a leak in August, the cost-per-pound of reclaimed R-22 plus the time it takes to track and repair the leak often pushes the math toward replacement — particularly because a new system also unlocks SEER2 gains and better humidity control.

See also:R-410A refrigerant·AC refrigerant explained·repair vs replace framework

R-410A

Cooling

R-410A is the HFC refrigerant in 2006–2024 residential AC; phasing down for new equipment starting January 2025.

R-410A is a hydrofluorocarbon (HFC) refrigerant blend (50/50 R-32 and R-125) that replaced R-22 in residential air-conditioning equipment starting in the early 2000s. It operates at roughly 50–60% higher pressure than R-22, requires copper line sets and components rated for that pressure, and uses POE (polyolester) oil — never mineral oil. R-410A has zero ozone-depletion potential but a high global warming potential (GWP ≈ 2,088). Under the AIM Act, the U.S. is phasing it down for new residential AC and heat-pump production: as of January 1, 2025, new equipment for the residential market ships with low-GWP A2L refrigerants such as R-454B or R-32. Existing R-410A systems continue to be serviced normally.

Why it matters in South Louisiana

Almost every residential AC and heat pump installed in South Louisiana from about 2006 to 2024 runs R-410A. Owners of those systems don't need to panic — service is still routine — but anyone replacing a condenser in 2025 or later will be putting in an A2L unit (R-454B is the dominant choice for residential AC). New refrigerants demand updated leak-detection equipment and brazing practices, which is why reputable contractors invested in A2L training through 2024.

See also:R-454B low-GWP refrigerant·R-22 legacy refrigerant·AC refrigerant explained

R-454B

Cooling

R-454B (sold as Opteon™ XL41 or Puron Advance™) is a low-GWP hydrofluoroolefin (HFO) refrigerant blend — about 68.9% R-32 and 31.1% R-1234yf — designed as the residential replacement for R-410A under the AIM Act. It is classified A2L by ASHRAE: low toxicity, mildly flammable. Its global warming potential of approximately 466 is roughly 78% lower than R-410A's. Operating pressures are similar to R-410A (about 5–10% lower), allowing manufacturers to use familiar copper line sizes, but A2L flammability requires listed leak-detection sensors in the indoor unit, listed components, brazing practices that account for ignition risk, and EPA Section 608 technicians trained to handle A2L refrigerants.

Why it matters in South Louisiana

Starting in 2025, new residential central AC and heat pumps installed across Metairie, the Northshore, and the West Bank ship with R-454B or R-32. The day-to-day homeowner experience is unchanged — A2L flammability is mild and only matters when a leak meets an ignition source in a confined area. Homeowners pricing replacements in 2025 and beyond should confirm their contractor has documented A2L training and the correct leak-detection equipment.

See also:R-410A phase-down context·AC refrigerant explained·air conditioning service

Return Air

Ducts & Distribution

Return air is the air drawn out of the conditioned space, through the filter and return ductwork, and back to the air handler to be reconditioned. The return side of a residential duct system is responsible for half of the system's total external static pressure budget, yet it is routinely the most undersized side of an existing install. Common return-air problems include too few return grilles for the home's floor plan, undersized return ducts, closed-door pressurization (bedrooms with closed doors that have no transfer path back to a return), and high-MERV filters in undersized return openings. Symptoms include rooms that won't cool, whistling around doors, and high static-pressure readings.

Why it matters in South Louisiana

A huge slice of Greater New Orleans housing — especially older Lakeview, Bywater, and shotgun-style homes — has a single central return that worked for a 2.5-ton system in 1995 but chokes a modern 3-ton variable-speed install. Adding a second return, upsizing the existing return drop, or installing transfer grilles in bedroom doors is often a higher-leverage fix than equipment replacement.

See also:static pressure·Manual D duct design·ductwork 101

S

SEER2

Cooling

SEER2 is the current DOE seasonal cooling-efficiency rating, replacing SEER as of 2023.

SEER2 (Seasonal Energy Efficiency Ratio 2) is the U.S. Department of Energy standardized cooling-efficiency rating for residential air conditioners and heat pumps, adopted in January 2023 under the M1 test procedure. It measures cooling output (in BTU/h) over a typical season divided by the electricity consumed (in watt-hours). SEER2 replaced the legacy SEER number to better reflect real-world duct static pressure: most equipment rates roughly 4–5% lower under SEER2 than under SEER for identical hardware. In the Southeast region, residential central air conditioners must hit at least 15.0 SEER2 and heat pumps at least 14.3 SEER2. Higher SEER2 means lower kilowatt-hours per cooling-ton delivered.

Why it matters in South Louisiana

A SEER2 jump from 15 to 17 doesn't sound dramatic, but in Metairie or Algiers — where a 4-ton system can run 1,800+ hours a year — the kWh swing on an Entergy or Cleco bill is real, especially through the July–September peak. SEER2-eligible high-efficiency systems may also qualify for Cleco PowerWise rebates in qualifying classes. Pair high SEER2 with a properly designed duct system (Manual D) or you'll never see the rated efficiency.

See also:EER (peak-condition efficiency)·AC repair vs replace framework·air conditioning service

Static Pressure

Ducts & Distribution

Static pressure measures duct-system resistance against the blower; high static kills airflow and capacity.

Static pressure is the pressure that the air distribution system exerts against the blower as it pushes (and pulls) conditioned air through ducts, fittings, coils, and filters. It is measured in inches of water column (in. W.C.) with a manometer at specific test points. Total external static pressure (TESP) is the sum of the supply-side and return-side static drops external to the air handler. Most residential equipment is rated at 0.5 in. W.C. TESP; a healthy real-world install lands at or below 0.7 in. W.C. Higher static pressure cuts airflow exponentially, drops capacity, raises noise, accelerates blower wear, and is the single most predictive measurement of duct-system health.

Why it matters in South Louisiana

A static-pressure reading is the single most useful 60-second test on a Louisiana service call. Most underperforming systems in Slidell, Marrero, and Gentilly aren't low on refrigerant — they're choking on 1.2 in. W.C. of static pressure from undersized return ducts, dirty MERV-13 1-inch filters, or a crushed flex duct in the attic. Cypress Cooling measures TESP on every diagnostic and maintenance visit.

See also:Manual D duct design·return air sizing·ductwork 101

Subcooling

Cooling

Subcooling is the temperature difference between the saturation temperature of the refrigerant at the condenser pressure and the actual temperature of the liquid refrigerant leaving the condenser. It tells the technician how much heat has been removed from the refrigerant after it fully condensed — and is the primary charging measurement for TXV/EEV systems. A typical residential air conditioner targets 8–14°F of subcooling at design conditions; low subcooling usually points to undercharge or a non-condensing problem; high subcooling points to overcharge, restriction, or a stuck metering device. Subcooling is read at the liquid line near the condenser using a clamp-on thermometer plus a manifold or wireless probe.

Why it matters in South Louisiana

On a 95°F New Orleans afternoon, a technician seeing 4°F of subcooling on a TXV system shouldn't reach for a refrigerant jug — that's a diagnostic clue, not a refill cue. Heat-soaked condenser coils, restricted condenser airflow, and bad metering devices all reshape subcooling readings. Reading subcooling correctly is one of the simplest tests of whether your tech is diagnosing or just throwing parts and gas.

See also:superheat measurement·TXV / EEV metering devices·air conditioning service

Superheat

Cooling

Superheat is the degrees of refrigerant vapor above saturation leaving the evaporator; a primary charging metric.

Superheat is the number of degrees the refrigerant vapor leaving the evaporator coil is above its saturation temperature at the suction-line pressure. It's the primary charging metric for fixed-orifice (piston-metered) systems and a critical diagnostic on TXV/EEV systems. A typical target superheat at the outdoor unit's suction service port lands in the 8–20°F range depending on outdoor and indoor conditions and metering type. Low superheat means liquid refrigerant is flooding back to the compressor (a wet, dangerous condition); high superheat means the evaporator is starved — usually because of low charge, restricted metering, or insufficient indoor airflow. Manufacturers publish superheat charts indexed by outdoor dry bulb and indoor wet bulb.

Why it matters in South Louisiana

Indoor wet-bulb temperatures in Slidell or the Garden District in July are high enough that superheat math behaves differently than in a dry climate. A technician using a generic chart without correcting for actual indoor wet-bulb will misread the system, blame refrigerant level, and add gas the system didn't need. Properly measured superheat — combined with subcooling — is how Cypress Cooling avoids the “free top-off” service-call trap.

See also:subcooling measurement·TXV / EEV metering devices·air conditioning service

T

TXV / EEV

Cooling

A TXV (thermostatic expansion valve) or EEV (electronic expansion valve) is the metering device that controls how much liquid refrigerant flows into the evaporator coil. A TXV uses a sensing bulb and spring-loaded diaphragm to maintain a target superheat mechanically; an EEV uses a stepper motor commanded by a control board reading thermistor and pressure inputs, and can adjust hundreds of times per minute. Both replaced fixed-orifice (piston) metering, which can't adapt to changing conditions. EEVs are standard on inverter-driven and most two-stage residential equipment because variable-capacity compressors need variable metering to maintain proper superheat and subcooling across the operating envelope.

Why it matters in South Louisiana

An out-of-spec TXV or stuck EEV is one of the most commonly misdiagnosed failures in Louisiana service calls — it mimics low refrigerant charge, low airflow, or a failing compressor. Adding refrigerant to “fix” a TXV problem leads to flooded compressors and warranty headaches. Cypress Cooling's diagnose-first approach catches these by reading superheat and subcooling together rather than chasing pressures alone.

See also:superheat measurement·subcooling measurement·air conditioning service

U

UV-C

Indoor Air Quality

UV-C is the short-wavelength ultraviolet band (200–280 nanometers, with peak germicidal effect near 254 nm) used in HVAC systems to inactivate microorganisms by damaging their nucleic acids. HVAC UV-C is typically deployed in two ways: coil sterilization (a low-intensity lamp aimed at the evaporator coil, running 24/7 to prevent biofilm and mold growth on the wet coil surface) and air sterilization (a higher-intensity in-duct lamp that disinfects air as it passes, requiring higher wattage and short dwell times). UV-C lamps degrade over 9–14 months and must be replaced annually. Improperly mounted UV-C can damage flex duct, wiring insulation, and rubber gaskets — installation location and lamp shielding matter.

Why it matters in South Louisiana

Wet evaporator coils in a New Orleans summer are biological playgrounds — mold, biofilm, and bacterial slime form quickly on coils that drip condensate eight months a year. A properly placed coil-aimed UV-C lamp keeps the coil clean between maintenance visits, preserves heat-transfer efficiency, and reduces musty supply-air odors. For homes with mold sensitivity or post-flood remediation history, layered coil + in-duct UV-C is a reasonable add-on; for everyone else, coil-only is usually enough.

See also:evaporator coil·humidity in Louisiana homes·indoor air quality service

V

VOCs

Indoor Air Quality

VOCs (Volatile Organic Compounds) are carbon-based chemicals that easily evaporate into indoor air at room temperature. Common residential sources include formaldehyde and acetaldehyde from particleboard cabinetry and laminate flooring; benzene and toluene from paint, adhesives, and solvents; terpenes from cleaning products; and combustion byproducts from gas appliances. Indoor VOC concentrations are routinely 2–5× outdoor levels and spike sharply after new construction, remodels, and certain cleaning routines. VOC mitigation strategies include source control (low-VOC product selection), ventilation (mechanical fresh-air through an ERV per ASHRAE 62.2), and adsorption filtration (activated-carbon media in addition to particulate filtration — particulate filters do not capture gases).

Why it matters in South Louisiana

A post-Katrina, post-Ida rebuild wave means a significant slice of the South Louisiana housing stock has had recent flooring, paint, and cabinetry work — all of which off-gas VOCs for months. Activated-carbon-stage filtration paired with a small ERV is the reasonable solution: standard MERV-only filtration can't touch gas-phase pollutants, and “ozone-generating” purifiers create their own VOC reaction products and should be avoided.

See also:MERV particulate filtration·ACH ventilation rate·indoor air quality service