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That $400+ electric bill was probably not your heat pump being inefficient — it was auxiliary or emergency heat running when it should not have been. At RI Energy's $0.29/kWh, the difference between normal and EM HEAT is $300/month.
Walk to your thermostat. If it shows “EM HEAT” or“Emergency”, switch it back to normal“Heat” mode immediately. This single change could save you $200–$400 this month. EM HEAT should only be used during an actual compressor failure.
If “AUX” shows briefly during cold weather and then goes away, that is normal. It only becomes a problem if AUX stays on for hours.
Understanding these three heating modes is the key to managing your RI electric bill. All costs based on RI Energy's $0.29/kWh residential rate for a typical 2,000 sq ft home.
How It Works
Compressor extracts heat from outdoor air. Moves 3 units of heat per 1 unit of electricity (COP 3.0).
When It Runs
Above 25-30°F outdoor temp (most RI winter days)
How It Works
Electric resistance strips supplement the heat pump when it cannot keep up alone. Both run simultaneously.
When It Runs
Below 25-30°F, during temperature recovery from setbacks, or during defrost cycles
How It Works
Bypasses the heat pump entirely. ONLY electric resistance strips running. COP of 1.0 — pure resistance heating.
When It Runs
Should ONLY be manually activated when heat pump compressor fails
Ranked by how commonly we see each issue in Rhode Island homes. Check in order — the first three account for 80% of spike cases.
Someone switched to EM HEAT during a cold snap or power flicker and never switched back. The heat pump compressor is off entirely — you are heating with pure electric resistance at $0.29/kWh.
Fix
Check your thermostat immediately. If it says "EM HEAT" or "Emergency," switch back to normal heating mode. The heat pump will resume.
Setting the thermostat to 55°F at night and 70°F in the morning forces aux heat for 2-4 hours every recovery. At $0.29/kWh, each recovery costs $15-$30.
Fix
Keep setbacks to 2°F maximum. Use "Smart Recovery" setting so the heat pump warms gradually before wake time.
A gas furnace thermostat installed with a heat pump does not stage heating correctly. It may run aux heat as the primary heat source instead of the compressor.
Fix
Replace with a heat pump-specific thermostat (Ecobee, Nest, Honeywell T-series). RI Energy offers $50 rebates.
A clogged filter reduces indoor airflow, causing the system to short-cycle and rely more on aux heat. The heat pump cannot move enough air to heat efficiently.
Fix
Replace indoor air filter every 1-3 months. Use MERV 8-11 for heat pumps (MERV 13+ can be too restrictive).
A slow leak reduces heating capacity, so the system calls for aux heat more often. A 10% loss in refrigerant can reduce efficiency by 20%.
Fix
Annual heat pump tune-up should include refrigerant pressure check. Cost: $100-$200 for service; leak repair $200-$1,500.
A system designed for moderate climates may lose capacity below 20°F. RI regularly hits 10-20°F in January, overwhelming an undersized unit.
Fix
Ensure your heat pump is rated for ENERGY STAR Cold Climate (operation down to -13°F or lower). May require system replacement.
Snow piled against the outdoor unit blocks airflow, reducing efficiency and triggering more frequent aux heat and defrost cycles.
Fix
Keep 18-24 inches of clearance around the outdoor unit. After storms, gently brush snow away with a broom.
Based on a 2,000 sq ft Rhode Island home, 3-ton heat pump, January heating season. All at RI Energy's standard residential rate of $0.29/kWh.
Thermostat steady at 68°F, no setbacks, clean filter, properly sized system
$85-$120
Aux: < 5%
900 kWh/month
January cold snaps below 20°F, occasional defrost aux, small setbacks
$130-$200
Aux: 10-20%
1,300 kWh/month
Large setbacks, dirty filter, or undersized system. Aux running multiple hours daily.
$250-$400
Aux: 30-50%
2,000 kWh/month
Pure electric resistance heating. No heat pump compressor running at all.
$450-$650
Aux: 100%
3,200 kWh/month
The difference between optimal and EM HEAT?
$400+/month
At RI Energy rates. That is $2,000+ wasted over a single heating season.
Each of these changes reduces the amount of time your heat pump relies on expensive electric resistance strips. Combined, they can cut your winter bill by $100–$200/month.
Modern cold-climate heat pumps maintain capacity down to 5°F. Setting the aux lockout to 35°F prevents unnecessary aux heat during mild cold.
Saves $20-$40/monthThe biggest single factor. Never drop more than 2°F from your home temperature. Use smart recovery to preheat.
Saves $30-$60/monthSet minimum compressor run time to 10 minutes. Prevents short cycling that triggers aux heat during startup.
Saves $10-$20/monthRI homes with pets, wood stoves, or high traffic need monthly filter changes. Use MERV 8-11 for heat pumps.
Saves $10-$25/monthRefrigerant check, coil cleaning, and defrost board testing. Especially important for coastal RI homes with salt exposure.
Saves $50-$100/yearOlder RI homes lose 25-40% of heat through air leaks. Clean Heat RI covers weatherization as part of the rebate process.
Saves $30-$80/monthIf your system is 10+ years old, modern cold-climate units maintain 80% capacity at 5°F versus 50% for older models. Clean Heat RI covers 60% of the cost.
Saves $50-$150/monthYour RI Energy bill contains clues about whether your heat pump is operating efficiently or running excessive aux heat. Here is what to look for.
A 2,000 sq ft RI home with an efficient heat pump should use 800–1,200 kWh/month in January. If your bill shows 2,000+ kWh, aux heat is likely running excessively. Compare January to October (no heating/cooling) to isolate heating usage.
Compare this January to last January. If usage jumped 50%+ with no change in settings or weather, investigate refrigerant levels, filter condition, and thermostat programming. A gradual increase suggests a slow refrigerant leak.
RI Energy provides daily usage data online. Look for days with 2–3x normal usage — those are days aux or EM HEAT was running heavily. If every day is high, the problem is continuous (likely EM HEAT or thermostat misconfiguration).
Auxiliary heat (AUX) activates automatically when the heat pump cannot keep up — the compressor and electric strips run together. This is normal during very cold weather. Emergency heat (EM HEAT) completely bypasses the heat pump compressor and runs ONLY electric resistance strips. EM HEAT should only be used when the compressor has failed. At RI Energy's $0.29/kWh, EM HEAT costs 3x more than normal heat pump operation.
The most common causes are: (1) EM HEAT left on accidentally — check your thermostat immediately. (2) Large thermostat setbacks triggering heavy aux heat. (3) Wrong thermostat type that runs aux as primary heat. (4) Dirty air filter reducing efficiency. At $0.29/kWh, even moderate aux heat usage adds $50-$150/month.
At RI Energy's $0.29/kWh rate: minimal aux usage (5% of heating) adds $10-$20/month. Moderate aux during cold snaps (20%) adds $50-$80/month. Heavy aux from problems (50%) adds $150-$250/month. Full EM HEAT (100%) costs $350-$600/month total — that is pure electric resistance with no heat pump efficiency.
Only when the heat pump compressor has completely failed and you need temporary heating while waiting for repair. EM HEAT runs at $4.50-$7.00 per hour at RI rates. Never use it as a regular heating mode, during cold snaps, or because "it seems warmer." The heat pump automatically uses aux heat when needed — you do not need to intervene.
Check your thermostat: if the "AUX" indicator is on for more than 30 minutes at a time when outdoor temps are above 30°F, something may be wrong. Also check your electric bill — a 2,000 sq ft RI home should use $80-$150/month for heat pump heating in winter. Bills above $250/month suggest excessive aux heat.
You can set an "aux lockout temperature" on most thermostats. Setting it to 25-35°F prevents aux heat from activating above that outdoor temperature. Do not disable aux heat entirely — it protects your home during extreme cold. Instead, minimize it through proper thermostat settings, maintenance, and ensuring your system is properly sized.
Modern cold-climate heat pumps use 80% less aux heat than older models. Clean Heat RI covers 60% of system costs (max $11,500). ARPA funding expires December 31, 2026.