How to Install an Electric Wall Heater

Installing electric wall heater units often involves the following:

1. Meeting the manufacturer's clearance requirements
2. Verifying the required voltage and circuit capacity
3. Cutting the wall opening
4. Installing the wall can or mounting box
5. Routing the correct electrical supply
6. Connecting the heater and thermostat
7. Testing the unit

Because hardwired wall heaters use line voltage, call a licensed electrician if you lack electrical experience.

Choose a location that allows the heater to distribute warm air without being blocked by furniture, curtains, doors, or other objects.

Before cutting the wall opening, the installer should also check the wall cavity for:

• Plumbing
• Existing Electrical Wiring
• Studs
• Insulation
• Other Obstructions

Many wall heaters are installed near an interior wall to provide unobstructed airflow and heat output, but placement requirements vary by model.

Manufacturers like Cadet Heat usually recommend an interior wall and warn against spots where curtains, furniture, doors, or other objects can block airflow.

Always use the mounting height, clearance, and location requirements listed in the heater's installation manual.

Although wall heaters work differently depending on the model and controls, most installations follow the same general steps.

1. Turn Off the Power

• Turn off power at the breaker box and verify the circuit is de-energized before working with electrical wiring.

  *In most installations, you do not need to shut off power to the entire house. However, work involving the main service panel should only be performed by someone qualified to do so.

2. Mark and Cut the Wall Opening
• Use the dimensions in the heater's installation manual to mark the wall can location.
• Check the wall cavity for obstacles before cutting the full opening.
3. Route the Electrical Supply
• Route the required electrical supply from the panel to the heater location.
• The circuit should match the heater's voltage, wattage, amperage, and manufacturer requirements. Do not assume the heater can simply connect to a nearby circuit.
4. Install the Wall Can
• Secure the wall can or mounting enclosure inside the wall opening according to the manufacturer's instructions.
• Run the electrical supply into the enclosure through an approved cable connector or clamp.
• NOTE:The required wall heater parts and mounting hardware vary by model.
5. Connect the Heater and Thermostat
• Connect the heater and thermostat according to the manufacturer's wiring diagram.
• Wiring can vary depending on:
• Heater Voltage
• Thermostat Type
• Control Configuration
• Heater Model
• For separate line-voltage thermostats, incoming power may be identified as LINE, while the connection to the heater is labeled LOAD. Line-voltage thermostats interrupt the actual power supply to the heater (handling higher loads like 120V & 240V). Low-Voltage thermostats require a relay transformer.
• Always follow the specific wiring diagrams for both devices.
6. Install the Heater and Grille
• Secure the heater assembly inside the wall can and install the grille or cover.
• Make sure the intake and discharge areas remain unobstructed.
7. Restore Power and Test Operation

• Restore power and confirm that:

• The thermostat responds correctly
• The fan operates normally on fan-forced models
• The heater produces heat
• Airflow remains clear
• The heater cycles on and off normally

WARNING: If the breaker trips, the heater overheats, or the unit does not operate correctly, turn it off and have the installation inspected.

Electric wall heaters may use either a built-in thermostat or a separate wall-mounted thermostat.

• A built-in thermostat controls the heater directly from the unit.
• A wall-mounted thermostat allows temperature control from another location in the room.

Raising the thermostat setting does not increase the heater's rated wattage. It may simply cause the heater to run longer, increasing total energy use.

For more information, see our guide to Built-in vs External Thermostats.

If installation requires:

• A new circuit
• breaker work
• permanent wiring
• panel changes

Use A Qualified Electrician!

Manufacturer instructions should always take priority over general guidance because electrical and mounting requirements vary between wall heater models.

With an extensive selection of wall heaters from trusted brands, HomElectrical is your one-stop shop for renovations, construction jobs, and DIY projects.

Visit our Master Guide to learn more about wall heaters, their functions, and how they can keep your home warm.

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