Heating Troubleshooting
Heat Strips Not Working?
Tampa cold snap below 40°F, heat pump backup heat strips not kicking on? Common + usually fixable. CAC1819196.
Quick Answer
Heat strips failing in Tampa = (1) tripped breaker (separate from AC breaker), (2) failed relay/contactor ($279), (3) burned heat strip element ($279), or (4) wiring issue ($779 low voltage cable). Heat strips are rarely-used in Tampa so failures hide until cold snap. FREE diagnosis. Call (813) 343-2212.
Heat Strip Failure Causes
Tripped Breaker
Symptom: Separate 60A breaker for heat strips. Tripped = no heat strip power.
Reset breaker. If trips again: call.
Failed Relay
Symptom: Heat strips don’t engage when thermostat calls for aux heat.
Relay replacement $279.
Burned Heater Kit
Symptom: Strip element burned out. Breaker may trip.
Heater kit replacement $279 simple, $850 with wiring.
Low Voltage Wiring
Symptom: Thermostat not sending aux heat signal.
Low voltage cable replacement $779.
Why Heat Strips Rarely Matter and Suddenly Do (Tampa Climate Context)
Tampa Bay winters are mild, which is exactly why heat strip failures sneak up on homeowners. Your electric heat strips only engage when outdoor temperatures drop below roughly 40°F, and Tampa sees that kind of weather for just 15 to 25 days a year. The rest of the winter, your heat pump handles heating duty on its own by pulling warmth from outdoor air, and the strips sit idle inside your air handler.
That rarity is the problem. A burnt-out heat strip element or dead sequencer can sit undiagnosed for 10 or 11 months out of the year without anyone noticing. Then a cold snap rolls in from the Midwest, temperatures dip into the upper 30s overnight, and homeowners wake up at 4 AM to a 58°F house. We get the bulk of our heat strip calls the week after Christmas and the first two weeks of January.
Emergency Heat vs Auto Mode: What Actually Happens
Your thermostat has two heat settings for a reason. In Auto mode, the system runs the heat pump first and only kicks in the strips when outdoor temps drop low enough that the heat pump alone cannot keep up. In Emergency Heat (Em Heat), the heat pump is completely bypassed and the electric strips run alone as your only heat source.
This matters for diagnosis. If you switch your thermostat to Em Heat and nothing warm comes out of the vents after 2 or 3 minutes, your strips are confirmed dead. The heat pump is out of the picture in that mode, so cold vent air in Em Heat points directly at the strips, the sequencer, or the contactor.
How to Test Before the Cold Snap Arrives
We recommend every Tampa homeowner run a 2-minute heat strip test in October each year. Flip the thermostat to Em Heat, set it 3 degrees above room temperature, and wait 2 minutes. Put your hand on a supply vent. Warm air means your strips are working. If something feels off, call us for a FREE diagnosis before December.
The 5 Causes of Heat Strip Failure in Tampa Homes
| Cause | What Fails | Typical Repair Cost | How Common |
|---|---|---|---|
| Failed sequencer | Controls staged activation of strip banks, wears out from thermal cycling | $449 to $549 | 40% of calls |
| Failed contactor | Relay that energizes the strip circuit, pitted or welded contacts | $279 to $349 | 25% of calls |
| Open-circuit element | Burnt out nichrome wire inside the strip assembly | $349 to $499 per element | 20% of calls |
| Tripped limit switch | Safety shutoff triggered by overheating, often from a dirty filter or blocked return | $279 reset + FREE diagnosis of root cause | 10% of calls |
| Low-voltage control fault | Thermostat wire break or bad W2 signal, strips never get the call for heat | $279 to $449 | 5% of calls |
What a Tech Actually Measures
A single 5kW heat strip pulls roughly 20 to 22 amps at 240 volts. A 10kW strip pulls 40 to 45 amps. Most Tampa air handlers have a 10kW or 15kW total strip package, which means our clamp meter should read between 40 and 60 amps on the strip circuit when the thermostat calls for Em Heat. If we clamp the wire and see 0 amps with the thermostat calling, the fault is upstream in the sequencer, contactor, or control wire.
Is Running Emergency Heat All Day a Problem?
Yes, and your power bill will tell you so. Emergency Heat costs roughly three times more to run than normal heat pump operation because you have bypassed the efficient part of the system and are heating purely with electric resistance.
Let’s run the math on Tampa rates. TECO and Duke charge around $0.14 per kWh. A 10kW heat strip running at full capacity pulls 10 kWh per hour, which costs $1.40 per hour. During a cold snap, strips typically run 6 to 8 hours a day. That works out to $8.40 to $11.20 per day in strip usage alone. A 5-day cold snap adds $42 to $56 to your bill.
Signs Your Strips Are Running When They Should Not Be
- Heat pump reversing valve stuck, so the outdoor unit cannot switch to heat mode
- Defrost board failing, which can lock the system into a defrost loop
- Outdoor coil iced over in cold damp weather, blocking airflow
- Thermostat miscalibrated or set to Em Heat accidentally
If your heat pump is blowing cold air during a cold snap, the issue is usually in the outdoor unit, not the strips. See our heat pump blowing cold air guide.
60-Second DIY Self-Diagnostic Flowchart
- Set your thermostat to Heat mode, temperature 5 degrees above current room temp. Wait 3 minutes.
- Put your palm flat on a supply vent. If vent air feels warm, system is working. If cold, go to step 3.
- Look outside at the condenser unit. Is it running and the fan spinning?
- Outdoor unit NOT running + vent is cold = strips are the primary failure.
- Outdoor unit IS running + vent is cold = heat pump problem, not strips.
- Switch thermostat to Emergency Heat (Em Heat) mode. Wait 2 minutes.
- Check vent again. Warm air in Em Heat mode = strips work, heat pump is the issue. Cold air in Em Heat = strips are dead.
What to Do Right Now
- Check breaker, separate breaker from AC.
- Set thermostat to HEAT + AUX HEAT (or EM HEAT) to force strips on.
- Listen for clicks from air handler when strips activate.
- Call for FREE diagnosis.
FREE diagnosis. Heater kit: $279 (or $850 with wiring). Relay: $279. Wiring: $779.
FAQ
When do heat strips kick in?
Usually below 40°F outside when heat pump can’t keep up, or during defrost cycle. Tampa uses them 10-20 nights/year.
Emergency heat mode?
Forces heat strips only, bypassing heat pump. Useful if heat pump is broken. Much higher electric bill.
Why didn't I notice sooner?
Tampa barely uses them. Failure goes unnoticed until a cold snap forces the issue.
Check before winter?
Our Premium Therapy Plan includes fall/winter heating check ($20/mo per system).
What is the difference between Emergency Heat and Auto mode?
Auto mode runs the heat pump first and brings in the electric strips as a supplement when outdoor temps drop. Emergency Heat bypasses the heat pump entirely and runs the strips alone.
How much does it cost to run heat strips in Tampa?
Roughly $2 to $4 per hour for a typical 10kW to 15kW strip package at Tampa electric rates. A full cold snap that triggers strip use for 5 days adds $50 to $150 to your bill.
My heat pump stopped working, should I use Emergency Heat?
Yes, as a stopgap. But call us right away because Em Heat costs about 3 times more than normal heat pump operation.
How do I know if my heat strips burned out?
Run the Em Heat test. Switch the thermostat to Em Heat, wait 2 minutes, and feel a supply vent. Cold air in Em Heat mode confirms the strips are dead.
How often do heat strips need replacement in Tampa?
10 to 15 years is typical. Tampa strips rarely get used, so the elements tend to last longer than the sequencer or contactor controlling them.
Why is my electric bill so high in January?
Heat strips. During cold snaps, strips can add $50 to $150 to a single month’s bill.
Can I run my heat pump without heat strips?
Yes, but it will struggle below 40°F outdoor temps. The strips exist specifically to supplement the heat pump when outdoor air is too cold for the pump to extract enough warmth on its own.
Should I replace my heat strips with a dual-fuel system?
No. Dual-fuel systems make sense in colder climates where strips would run 40+ days a year. Tampa sees 15 to 25 cold days, and the gas line install cost does not pay back.
Home Therapist serves all of Tampa Bay. HVAC license CAC1819196. Call (813) 343-2212 for FREE diagnosis on any heat strip or heat pump issue.