HVAC Heat Strip Sizing: kW Ratings Explained
When you replace an HVAC heat strip, the kW rating has to match your system. Get it wrong and you’ll trip breakers, overload wiring, or come up short on heat. Here’s how sizing works.
What the kW rating means
A heat strip’s rating — commonly 5, 7.5, 10, 15, or 20 kW — is how much electric heat it produces. More kW means more heat, but also more current draw and bigger wiring/breaker requirements.
Matching the strip to your system
The correct size depends on three things:
- The air handler’s design — it’s rated for a maximum heat-strip kW.
- The circuit and breaker — must handle the strip’s amperage.
- Your heating load — how much backup heat the space actually needs.
Rule of thumb: 1 kW ≈ 3,412 BTU/h. A 10 kW strip puts out roughly 34,000 BTU/h of heat.
Why you can’t just “size up”
Fitting a bigger strip than the air handler or circuit is rated for is a fire and code risk — it can overheat wiring and trip or weld breakers. Always match the original spec unless an HVAC pro has redesigned the circuit.
Replacing a heat strip
Match the kW, voltage, and physical fit of the original. Not sure what you have? Send us the make and model or a photo of the data tag and we’ll match it — shipped across Canada.
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