Install an Electric Heat Kit (Strip Heat)

Match the kit kW to the air handler and the electrical service (may need a second circuit), land it per the wiring diagram so sequencers stagger the elements, size the breaker/wire, verify airflow first, then check per-element amp draw and temperature rise.

Approx. 150 min

Before you start

•Air handler model confirmed as rated to accept the kit kW (the cabinet/coil listing limits max kW); kit voltage (240/208) matches the supply.
•Electrical service capacity known — a large kit may exceed a single breaker/feeder and require a second circuit (many kits ship with two power blocks/breakers for exactly this).
•Design heat load and the air handler's rated CFM are known so the temperature rise will land in range.

Tools & materials

Manufacturer wiring diagram for this air handler + kit · Clamp meter (true-RMS) and a voltmeter · Correct breaker(s) and copper conductors sized for the kit MCA · Hand tools, wire connectors, torque screwdriver · Thermometers for supply/return temperature rise

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Match kW, service & circuits

Match the heat-kit kW to the air handler and service
Pick a kit kW the air handler is listed to accept (don't exceed the cabinet rating) and that the building service can feed. Calculate the kit's load: kW draws a lot of amps (e.g. 10 kW @ 240 V ≈ 41.7 A), so confirm the panel/feeder has room before committing.
Target: Kit kW ≤ air handler's listed max kW; load amps = (kW × 1000) ÷ volts
Provide a second circuit if the kit needs it
Larger kits split into two heater stages each on its own power block/breaker because a single circuit/breaker can't carry the whole load. Land each block on a properly-sized breaker; don't bridge two blocks onto one undersized feeder.
Target: One breaker/feeder per power block; no power block fed beyond its rated ampacity
⚠ Lock out and verify the air handler is de-energized at the disconnect/panel before opening it.

Wire per the diagram

Fish in and land the kit per the wiring diagram
Mount the kit in the air handler and wire it exactly per the manufacturer's diagram — the low-voltage control wiring (W1/W2), the sequencers/relays, the limit/fuse links, and the line connections. Don't improvise the control logic.
Tools: Manufacturer wiring diagram
Target: All connections per the kit/air-handler wiring diagram; control wires (W1/W2) landed correctly
Confirm sequencers/relays stage the elements
Sequencers (or relays) bring the elements on in steps a few seconds apart rather than all at once, so the inrush doesn't slam the service and the blower has air moving before each element heats. Verify each stage energizes in turn on a call.
Target: Elements stage on sequentially (not simultaneously); each stage drops out on loss of call

Breaker & wire sizing

Size the breaker and conductors to the kit MCA
Size the overcurrent device and copper conductors to the kit's marked MCA/MOCP, not just the running amps — electric heat is a continuous load (sized at 125%). Use the kit's listing; oversizing the breaker defeats the wire protection.
Target: Breaker = kit MOCP; conductors ≥ kit MCA ampacity (electric heat sized at 125% continuous)

Verify airflow, amps & rise

Verify the blower runs and airflow is established FIRST
Confirm the blower starts and air is actually moving across the heat kit before energizing the strips. The kit's sequencers/interlock should not let elements heat without the blower; never bypass that or jumper the strips on with no airflow.
Target: Blower proven running with airflow established before any element is energized
⚠ NEVER energize electric heat strips without the blower running and airflow established — it will overheat, trip the limits, and can start a fire.
Check amp draw per element against the nameplate
With each stage energized, clamp each element/circuit and compare the draw to the rated amps. A low/zero reading means an open element or fuse link; a high reading means a wiring/voltage problem.
Tools: Clamp meter
Target: Per-element amp draw within tolerance of the nameplate/calculated value; no open elements
Verify temperature rise across the air handler
Measure supply and return air temperature with all stages running and the blower at the heating tap. The rise should land in the air handler/kit listed range; too high means low airflow, too low means an element not firing.
Target: Supply − return ΔT inside the listed range for the air handler/kit at the heating blower speed