If you are considering a heat pump for your Acadiana home, you are already thinking in the right direction. Heat pumps cool your home in summer and heat it in winter using the same system, and they do both jobs more efficiently than a traditional AC and furnace combo.
But here is what most people do not realize: the quality of the installation matters just as much as the equipment itself. Two identical heat pumps installed in similar homes can perform very differently depending on who put them in. A good installation means lower bills, better comfort, and a system that lasts. A bad one means the opposite.
This guide walks you through every step of a proper heat pump installation so you know what to expect and what questions to ask before you hire anyone.
What Makes Heat Pump Installation Different from Standard AC
A heat pump does everything an air conditioner does, plus heating. It moves heat in or out of your home depending on the season. In summer, it pulls heat out and pushes it outside. In winter, it pulls heat from the outdoor air and brings it inside.
That dual role adds a few steps to the installation that you would not have with a standard AC:
- Emergency heat strips need to be properly wired and programmed. These electric heating elements serve as backup when outdoor temperatures fall low enough that the heat pump needs help.
- The reversing valve switches refrigerant flow between heating and cooling modes. It must be tested in both directions during startup.
- Thermostat programming is more involved. A heat pump thermostat needs to manage the heat pump itself, the backup heat strips, and the defrost cycle. Getting this right takes time and training.
- Defrost mode must be properly configured. When humidity in the air freezes on the outdoor unit during cooler weather, the system needs to reverse briefly to clear the ice. In Acadiana’s mild but humid winters, proper defrost setup matters.
Each of these extra steps is where shortcuts get taken. This guide will show you what the right process looks like.
Step 1: The In-Home Estimate and Load Calculation
Before any equipment gets ordered, a trained comfort specialist should visit your home. This is not just a sales visit. It is an essential part of making sure the right system goes into your home.
During this visit, the technician measures your home, checks insulation levels, looks at your existing equipment, and assesses your ductwork. Most importantly, they run a Manual J Load Calculation, which is the only accurate way to determine how much heating and cooling capacity your home actually needs.
Sizing a heat pump correctly is critical. An undersized system will run nonstop on hot summer days and struggle to keep up. An oversized system will short-cycle, meaning it turns on, does its job too quickly, then shuts off before it removes enough humidity from the air. In Acadiana, where humidity is relentless for most of the year, an oversized system will leave your home feeling sticky and uncomfortable no matter what the thermostat says.
Never let a company size your system without a load calculation. Guessing based on square footage or matching the old unit size is how homes end up with comfort problems that never get resolved.
Step 2: The Install Team Arrives
On installation day, expect a call or text before the team arrives. A professional company sends you the names and photos of who is coming so you know who to let in.
When the lead technician arrives, they will review the full scope of work with you before anything starts: the equipment being installed, any additional components, and any notes from your estimate. While that review happens, the rest of the crew gets the truck unloaded and lays down floor protection inside your home.
Step 3: Removing the Old System
The first step is always shutting off all electrical power and gas supply to your existing equipment. This is a safety requirement, not optional.
Your old system contains refrigerant that must be captured using a certified recovery machine. Venting refrigerant into the atmosphere is illegal. Every technician on a licensed crew who handles refrigerant must carry their own EPA certification.
Once the refrigerant is out, the electrical connections are cut. A proper installation replaces both the outdoor disconnect box and the flexible electrical connection (called a whip) at the same time. Reusing old wiring on a new heat pump system is a shortcut that can create problems down the road and should not be accepted.
Step 4: Preparing the Outdoor Pad
Modern heat pump outdoor units are physically larger than older models because larger coils are part of what makes them more efficient. This sometimes means the existing pad and location need to be adjusted.
A gravel base is used to level the surface. The new unit sits on a composite pad designed specifically for outdoor HVAC use. Composite pads absorb vibration, drain well, and are built to last the full life of the system. Concrete pads crack and shift over time and are harder to correct once that happens. Composite is the right choice.
Step 5: Removing the Indoor Coil
Your indoor evaporator coil sits above or below your air handler and is the indoor half of the refrigerant system. It needs to come out before the new one can go in.
Access can be simple or complicated depending on your home’s layout. Tight closets, finished attic spaces, and awkward mechanical rooms slow this step down. If access is especially difficult, your installer should note this upfront in the estimate.
Modern coils are taller than older ones, so the sheet metal plenum around the coil may need to be modified to fit properly.
Step 6: Running the New Refrigerant Lines (Line Set)
Two copper pipes called the line set run from your outdoor heat pump to your indoor coil: a larger suction line and a smaller liquid line. In almost all cases, the old line set should be replaced.
The reason is oil compatibility. Older refrigerant systems use a different oil than modern systems. If those oils mix, they can cause compressor failure over time. Only when the old line set is buried underground or inside a finished wall and genuinely cannot be replaced should it be reused, and in that case it must be flushed, cleaned, and pressure tested thoroughly.
New lines should be as straight and direct as possible. Each bend adds resistance and reduces system efficiency. Lines need to be secured every four to six feet, and metal clamps must never contact the copper directly because that creates a path for corrosion.
Step 7: Setting the New Outdoor Unit
With the pad ready and lines in place, the heat pump’s outdoor condenser unit is set on the pad. Before connecting anything, the installer should visually inspect the unit for shipping damage. Dents do not always affect function, but you deserve to know if the unit was damaged in transit, and you have the right to request a replacement.
The refrigerant lines are connected to the service valves on the unit. These valves allow future technicians to isolate refrigerant during service without losing the full charge, which saves money on every repair visit.
Step 8: Brazing, Pressure Testing, and Deep Vacuuming
This is the section where the most shortcuts get taken and where the long-term performance of your system is decided.
Brazing: Copper refrigerant connections must be permanently joined using a welding process called brazing. Brazing uses oxygen, acetylene, and a silver-based rod to create joints that hold under high pressure and temperature changes. During brazing, dry nitrogen must flow through the lines. This protects the inside of the copper from oxidizing as it heats up. Oxidation inside a refrigerant line causes microscopic debris that coats the compressor and internal components over time, shortening system life significantly. No nitrogen purge during brazing is a red flag.
Pressure testing: After brazing, the system is pressurized with dry nitrogen and held for a minimum of ten minutes. A pressure drop indicates a leak somewhere in the system. Every leak must be found and repaired before any refrigerant is introduced.
Deep vacuum: The entire system is then evacuated to remove air, moisture, and contaminants. Moisture inside a refrigerant circuit forms acids that attack compressor components from the inside. The vacuum must reach 500 microns or lower and hold there. If it does not hold, there is still a leak. Only after a successful vacuum hold is refrigerant released into the system.
These three steps are what define a professional installation. Many contractors skip or rush them. Yours should not.
Step 9: Electrical Connections, Including Emergency Heat
Heat pump electrical work is more involved than standard AC because of the auxiliary heat and defrost circuits.
A new disconnect box is mounted near the outdoor unit. This provides overcurrent protection and a safe shutoff point for future service calls. The low-voltage control wiring that runs from your thermostat to both the indoor and outdoor units must be correct for heat pump operation. This wiring also controls when the backup heat strips engage and when the system enters defrost mode.
If your existing thermostat wiring does not have enough conductors for a modern heat pump setup, new wire needs to be run. A good installer checks this during the estimate and includes it in the quote.
Your thermostat must be specifically designed and programmed for heat pump operation. A standard AC thermostat does not manage emergency heat or defrost properly. This is one of the most common installation oversights, and it costs homeowners real money in wasted energy.
Step 10: Thermostat Setup and Programming
Once the right thermostat is installed, it must be fully programmed. This includes:
- The outdoor temperature threshold at which backup heat strips activate
- The defrost cycle timing and temperature parameters
- The balance point between heat pump operation and emergency heat
- Any scheduling or smart home integration settings
A technician who programs the thermostat in five minutes did not complete this step correctly. Heat pump thermostat programming is detailed work that takes time.
Step 11: Condensate Drain Line
When your heat pump runs in cooling mode, it removes moisture from your home’s air. That water collects at the indoor coil and drains out through a PVC condensate line. This line must be properly sloped, include a trap to prevent airflow issues, and have an overflow safety switch installed. The safety switch shuts the system down if the drain ever gets clogged, preventing water damage to your home.
In south Louisiana, where every AC system runs heavily for months at a time, condensate management is especially important. A properly sized, sloped, and protected drain line is not optional.
Step 12: Commissioning in Both Heating and Cooling Modes
Commissioning is where the job is either done right or declared done prematurely. For a heat pump, both modes must be tested and verified.
Your technician should collect and record these data points while the system is running:
- Suction and liquid line pressures and temperatures
- Superheat and subcooling readings
- Supply and return air temperatures in cooling mode and heating mode
- Voltage and amperage on all motors
- Static pressure across the duct system
- Verification that defrost mode activates and terminates correctly
- Verification that emergency heat strips engage at the programmed threshold
- Refrigerant added, if any
These numbers confirm the system is running within the manufacturer’s specifications. They also serve as a baseline for future service calls. A technician who turns the unit on, feels cold air at the vents, and calls the job complete has not commissioned anything.
Red Flags to Watch For During Any Heat Pump Installation
- No Manual J Load Calculation before equipment selection
- No permit pulled for the installation
- Refrigerant vented instead of recovered
- Old line set reused without flushing and pressure testing
- No nitrogen purge during brazing
- Vacuum process skipped or pressure target not reached
- Standard AC thermostat installed instead of a heat pump thermostat
- No commissioning in heating mode
- Defrost operation not tested
- Old materials and debris left behind
