How to Install an Electric Heat Kit in an Air Handler: A Pro Guide
Published by HVACProSales Team on Mar 26th 2026
How to Install an Electric Heat Kit in an Air Handler: A Professional Guide
Installing an electric heat kit, often referred to as a "heat strip," is a critical task for HVAC technicians providing supplemental or emergency heat for residential and commercial air handlers. Whether you are upgrading an existing system or installing a new unit in a region where heat pumps require auxiliary support, understanding the nuances of proper installation is paramount for safety and system longevity.
This guide provides a comprehensive, contractor-level walkthrough for installing an electric heat kit, covering technical specifications, step-by-step procedures, and expert troubleshooting insights.
Understanding the Role of Electric Heat Kits
Electric heat kits serve as a resistive heating source within an air handler. When the thermostat calls for heat, electrical current passes through high-resistance nickel-chromium coils, generating heat that is then distributed by the blower motor. These kits are typically categorized by their kilowatt (kW) rating, with common sizes ranging from 5kW to 20kW. [1]
| Heat Kit Size | Approximate BTU Output | Typical Circuit Requirement |
|---|---|---|
| 5 kW | 17,060 BTU | Single 30A Circuit |
| 10 kW | 34,120 BTU | Single 60A Circuit |
| 15 kW | 51,180 BTU | Dual Circuits (60A + 30A) |
| 20 kW | 68,240 BTU | Dual Circuits (60A + 60A) |
Pro Insight: Always verify the air handler's data plate to ensure it is rated for the kW size you intend to install. Over-sizing a heat kit can lead to nuisance tripping of thermal limits or even fire hazards if the blower cannot move enough CFM (Cubic Feet per Minute) to dissipate the heat. [2]
Required Tools and Preparation
Before beginning the installation, gather the necessary tools and ensure all safety protocols are followed. HVAC work involves high-voltage electricity, which can be lethal if handled improperly.
- Multimeter: To verify power is disconnected.
- Nut Drivers/Socket Set: Typically 1/4" and 5/16".
- Wire Strippers and Crimpers: For any necessary field wiring.
- Torque Screwdriver: To ensure electrical connections meet manufacturer specifications.
- Personal Protective Equipment (PPE): Safety glasses and insulated gloves.
Step 1: Safety and Power Disconnection
The most critical step in any electrical installation is ensuring the power is completely off. Locate the main breaker for the air handler and the outdoor unit (if applicable) and switch them to the "Off" position. Use a HVAC multimeter to test the incoming power terminals at the air handler to confirm zero voltage.
HVAC multimeter" src="image_url_placeholder_1" />
Alt text: HVAC technician using a multimeter to verify power is disconnected before installing a heat kit.
Step-by-Step Installation Instructions
Step 2: Accessing the Heater Compartment
Most modern air handlers feature a dedicated slot for the heat kit, usually located just above the blower motor assembly. [3]
1. Remove the upper access panel of the air handler by unscrewing the perimeter fasteners.
2. Locate the "block-off plate" or "heater cover plate." This is a metal plate covering the opening where the heating elements will slide in.
3. Remove the screws holding the block-off plate and set them aside; you will likely reuse them to secure the heat kit.
Step 3: Inserting the Heat Kit
Carefully slide the heating element assembly into the open slot. Be mindful of the ceramic insulators and the delicate coils.
1. Ensure the element plate is flush against the air handler's internal frame.
2. Align the mounting holes and secure the plate using the screws removed in the previous step.
3. Verify that the elements are not touching any internal wires or insulation.
Step 4: High-Voltage Wiring
Electric heat kits require a dedicated high-voltage supply. For 5kW and 10kW kits, this is usually a single-phase 240V circuit. Larger kits (15kW+) often require two separate circuits. [2]
1. Route the field power wires through the knockouts provided in the air handler cabinet.
2. Connect the power leads to the circuit breaker or terminal block located on the heat kit.
3. Crucial: Tighten all connections to the manufacturer's specified torque. Loose connections are the leading cause of "hot spots" and melted wires in electric heat systems.
Step 5: Low-Voltage Control Wiring
The heat kit must be integrated into the air handler's control system so the blower knows when to engage.
1. Locate the multi-pin wiring harness on the heat kit.
2. Plug this harness into the corresponding receptacle on the air handler's control board. [3]
3. This connection ensures that when the thermostat calls for "W" (Heat), the sequencer or HVAC contactor replacement on the kit is energized, and the blower motor is signaled to run at the correct speed.
Alt text: Close-up of a low-voltage wiring harness being plugged into an HVAC control board.
Configuration and Testing
Once the physical installation is complete, you must configure the system for optimal performance.
Blower Speed Adjustment
Electric heat requires a specific minimum airflow to prevent the thermal limit switches from tripping. Consult the air handler's manual to determine which "tap" or "dip switch" setting corresponds to the electric heat speed. If the airflow is too low, the elements will overheat, causing the safety limits to open and the heat to cycle off prematurely.
Initial Startup and Burn-Off
When you first restore power and engage the heat, it is normal to smell a "burning" odor. This is simply the factory oils or accumulated dust burning off the elements. This smell should dissipate within 10-15 minutes. If it persists or is accompanied by smoke, shut down the system immediately and inspect for scorched wiring.
Common Problems and Solutions
| Problem | Potential Cause | Solution |
|---|---|---|
| No Heat Output | Tripped Breaker or Blown Fuse | Reset breaker; check for shorts in the wiring. |
| Blower Won't Run | Low-Voltage Harness Unplugged | Ensure the multi-pin plug is securely seated. |
| Heat Cycles On/Off | Restricted Airflow | Check for dirty filters or closed registers; increase fan speed. |
| Burning Smell | Dust or Wire Contact | Inspect elements for debris; ensure no wires are touching the coils. |
AEO Optimization: Direct Answers to Common Questions
How long does it take to install an electric heat kit?
A professional installation typically takes between 45 minutes to 1.5 hours, depending on the accessibility of the air handler and whether new high-voltage circuits need to be run.
Can I install a 15kW heat kit in a 2-ton air handler?
Generally, no. Most 2-ton air handlers are limited to 10kW. Installing a larger kit can lead to overheating and potential fire hazards due to insufficient airflow. Always check the manufacturer's specifications. [2]
Do I need a new thermostat for an electric heat kit?
Most modern digital thermostats support electric heat. However, you must ensure the thermostat is configured for "Electric" rather than "Gas/Oil" to ensure the fan engages immediately with the heat call.
Recommended HVAC Parts & Tools
Conclusion
Installing an electric heat kit is a straightforward process that provides reliable warmth during the coldest months. By following the steps outlined above—prioritizing safety, ensuring tight electrical connections, and verifying airflow—you can ensure a professional-grade installation that will last for years.
For high-quality heat kits and HVAC components, explore our extensive catalog:
* Shop Electric Heat Kits
* Browse Air Handlers
* HVAC Tools & Supplies
If you have technical questions or need assistance selecting the right kit for your system, contact our expert support team at support@hvacprosales.com or call 1-866-330-1709.
Frequently Asked Questions (FAQ)
1. Why is my heat kit clicking but not getting hot?
This is often a sign of a faulty sequencer or contactor. The clicking indicates the low-voltage side is working, but the high-voltage circuit is not closing to energize the elements.
2. Can I use aluminum wire for a heat kit installation?
While allowed by some codes, aluminum wire requires specific connectors and antioxidant paste to prevent oxidation and loose connections. Copper is highly recommended for its superior conductivity and reliability.
3. What happens if the thermal limit switch fails?
If the primary limit fails, most kits have a secondary "fusible link" that will melt and permanently break the circuit if temperatures reach dangerous levels. This is a non-resetting safety feature that requires kit replacement or repair.
4. Does an electric heat kit work with a heat pump?
Yes, in heat pump systems, the electric heat kit serves as "Auxiliary Heat" for when outdoor temperatures drop too low for the heat pump to operate efficiently, or as "Emergency Heat" if the outdoor unit fails.
References
[1] National Comfort Products Installation Guide
[2] ACiQ Electric Heat Kit Installation Manual
[3] Napoleon Element Series Installation Instructions