By Scott Gieseler · Published · Updated
A thermostat setting of 78°F (about 26°C) can be a starting point during a South Louisiana heat wave if everyone at home stays comfortable. It is not a universal safe temperature. Choose a cooler setting when needed, and raise it while away only if the home remains suitable for anyone and any pets still there.
When the temperature goes above 90°F, many homeowners ask if lowering the thermostat a few degrees keeps the house comfortable. The answer depends on the system, the house and indoor humidity. In Kenner and Metairie, humid air can feel warmer than drier air at the same temperature because sweat evaporates less easily. NOAA explains how humidity affects cooling.
Below we explain how to adjust a 78°F starting point, use smart thermostat setbacks and keep up with maintenance during a long heat wave. The goal is to give you clear steps you can take now and show when to call Tegridy Air. If the home becomes too hot, move to an air-conditioned place rather than waiting for a repair.
Using 78°F as a Starting Point for Comfort and Efficiency
A 78°F setting may balance comfort and cooling demand in some homes, but there is no single sweet spot for everyone. A lower setpoint generally calls for more cooling; it does not automatically cause more on/off cycles. Runtime depends on outdoor conditions, equipment capacity and controls.
A thermostat setpoint does not guarantee humidity control. Measure indoor relative humidity with a hygrometer: EPA recommends keeping it below 60%, ideally 30–50%. If the house stays damp, look for moisture sources and have the cooling system checked. A separate dehumidifier may help when the AC cannot manage the moisture load.
Using a higher cooling setting when it remains comfortable can reduce energy use, but savings vary with the weather, home and schedule. There is no reliable 3–5% saving per degree for every home. A steady setting also cannot cure short-cycling; repeated unusually brief starts and stops need diagnosis.
Using a Smart Thermostat for Automatic Setbacks
A compatible smart thermostat lets you program temperature changes. Depending on the model, it may use schedules, occupancy or learning features. Start with your comfortable home setting and try a modest increase while away, checking indoor humidity and conditions when you return. An 84°F away setting is not right for every home, occupant or pet.
Some smart thermostats offer geofencing, which uses your phone’s location to help detect when you leave or return. In Metairie or Kenner, check the device’s settings and account for other people at home before using this feature. Availability and behavior vary by model; ENERGY STAR does not require geofencing.
Some smart thermostats show how long the heating or cooling system ran. These reports can help you spot changes, especially when compared with similar weather. They do not necessarily measure electricity use or show which rooms used the most cooling. See the manufacturer’s documentation, such as Google Nest’s Energy History guide, for what your model reports.
Managing Humidity and Indoor Air Quality
High humidity is a big comfort problem in South Louisiana. Even if the temperature feels right, sticky air can make the house feel warmer. Your central AC removes moisture while it cools, but results depend on sizing, runtime, airflow and the home’s moisture load. A clean coil and correct airflow help; they do not guarantee humidity control.
If your system has a “dry mode” or dehumidification control, follow its manual or ask the installer how to use it. These controls work differently across systems; do not change internal blower settings yourself. Keep supply and return grilles unobstructed, and ask about return-air paths if closed rooms feel stuffy.
Air purifiers and suitable high-efficiency filters can improve indoor air quality by capturing airborne particles. Before choosing MERV-13, check your HVAC manual or ask a technician whether the fan and filter slot can accommodate it. EPA’s air-cleaner guide explains filter selection. Filtration does not replace moisture control or fixing a mold problem.
Inspect filters regularly and clean or replace them according to the equipment and filter instructions. A clogged filter can reduce airflow and cooling efficiency and contribute to coil icing. During heavy use, pets or dusty conditions may mean the filter needs attention sooner.
Seasonal Maintenance and Cost-Focused Service Overview
Even the best thermostat cannot fix a system that needs service. During a heat wave, poor performance can show up as higher bills and less comfort. A professional tune-up before the season starts can catch some problems early, although it cannot prevent every breakdown. ENERGY STAR’s maintenance checklist describes common inspection tasks.
A maintenance visit may include checking refrigerant charge, motors, controls and electrical connections. If refrigerant is low, a qualified technician should diagnose why and discuss any leak repair before recharging. This article lists refrigerant at $125 to $225 per pound as a reference range; confirm current pricing for the refrigerant your system requires, including R-454B. Do not mix or substitute refrigerants yourself.
Motor replacement costs vary by type. The reference ranges listed here are $450-$800 for a standard single-speed motor and $1,000-$1,200 for a variable-speed ECM motor. Compressor replacement is listed at $1,800-$2,900; capacitor or contactor work at $200-$450; and leak repairs at $400-$900 plus refrigerant. Actual pricing depends on diagnosis, equipment and the work included. Ask whether any diagnostic fee is included in the quote.
Tegridy Air’s published dispatch fee for Greater New Orleans is $109. Repair pricing is quoted after diagnosis and before the repair proceeds.
When to Call a Professional: Signs Your System Needs Attention
If you notice weak or uneven airflow, schedule a visit from a qualified technician. A clogged filter, blower issue or duct problem may be involved, but the symptom alone does not identify the cause.
New rattling, squealing or grinding can indicate loose or failing parts. If you see ice on the evaporator coil or refrigerant lines, turn cooling off and contact a technician. Airflow restrictions and refrigerant problems are possible causes. Do not chip the ice, heat the coil or open equipment panels to investigate.
A higher electric bill can reflect hotter weather, rate changes or equipment problems, so compare usage as well as cost. A persistent burning smell requires prompt attention: stop using the system if you can safely do so and call for service. For smoke, fire, a suspected gas leak or a carbon monoxide alarm, leave and call 911 from a safe location. If you suspect gas, do not operate switches. CPSC’s CO guidance and PHMSA’s gas-leak guidance explain the emergency precautions.
Tegridy Air offers AC repair, duct repair, and air purification services in Kenner and Metairie. A diagnostic visit can help identify the issue. The technician will explain repair options and costs before any work starts.
Energy-Saving Habits Beyond the Thermostat
Thermostat settings are only part of the equation. Close blinds or shades on sun-exposed windows during the hottest part of the day. Direct sunlight adds heat, making the AC work harder. DOE’s home energy tips include window coverings and regular filter care.
Use ceiling fans in occupied rooms for comfort and turn them off when you leave. You may be able to raise the thermostat a little while still feeling comfortable. Fans do not lower the room temperature: CDC advises using fans only when indoor temperatures are below 90°F. If the home is too hot, use air conditioning or move to a cooled location.
- Seal gaps around doors and windows with weather-stripping or caulk.
- Keep supply and return vents unobstructed; have persistent room-to-room airflow problems checked.
- Turn off unnecessary lights and appliances that generate heat.
If your home needs efficiency upgrades, consider an energy assessment before adding attic insulation or changing the roof surface. The useful improvements depend on existing insulation, air leaks, roof materials and installation cost. Ask for an estimate of the benefits for your home.
Final Thoughts
Treat 78°F as an optional starting point, then adjust for comfort, indoor humidity and household needs. Use suitable thermostat schedules, keep up with maintenance and reduce avoidable heat from sunlight and appliances. During a heat wave, staying safely cool matters more than hitting a particular setpoint.
For non-emergency warning signs or questions about system size, call Tegridy Air to discuss diagnosis and a quote. If someone may have heat stroke, including confusion or loss of consciousness in the heat, call 911 and begin cooling while help is on the way. See CDC’s heat-illness guidance.
Dealing with this right now? Call Tegridy Air at 504-414-8655 or request a free quote online – we’re local to Kenner and Metairie.
(504) 414-8655
Related Reading
Frequently Asked Questions
How often should I replace my HVAC air filter during a heat wave?
Check the HVAC air filter at least monthly and more often during heavy use or dusty conditions. Replace or clean it when needed and follow the filter and equipment instructions; the thermostat itself usually has no air filter.
Is 78°F the right temperature for everyone?
No. It can be a starting point if it feels comfortable, but household needs and indoor humidity vary. Use a cooler setting when needed and follow any personal heat-safety advice from your healthcare professional.
Can a smart thermostat lower my electric bill by itself?
It can help by automating suitable schedules, but savings depend on your previous settings, occupancy, weather, equipment and home. Check compatibility and do not assume every model has the same learning or reporting features.
What should I do if my AC freezes up during a heat wave?
Turn cooling off and contact a qualified technician. Check only the safely accessible filter as directed by your manual. Fan-only operation may help thaw ice if the manual permits and there is no electrical or water hazard. Do not chip the ice or restart cooling before the cause is addressed.