Heat Pump Emergency Heat Explained
A heat pump is an energy-efficient heating and cooling system that transfers heat between your home's indoor and outdoor units. During normal operation, the heat pump efficiently warms or cools the home by moving refrigerant that absorbs or releases heat outside. However, in extremely cold weather, heat pumps can struggle to extract enough warmth from the external air mass. This is where emergency heat comes in handy as a vital backup heating source.
The emergency heat function on a heat pump system engages a separate secondary heating method powered by electricity, gas, or oil. This backup system is manually activated via a switch or setting on the thermostat and completely bypasses the heat pump. Emergency heat is only used when the main heat pump cannot keep your home's temperature at the desired setpoint.
How Emergency Heat Works
When emergency heat is switched on, it draws power from a backup system that runs separately from the heat pump hardware. This is usually an electric heating system, furnace, or separate heat coils. Emergency heat produces warmth without relying on the heat pump's indoor and outdoor units and compressor. It's essentially an emergency backup when the heat pump struggles to extract enough heat from the exterior cold air.
Manually Activated
Emergency heat can only be activated manually via a switch or button on your heat pump's thermostat interface. This bypasses the main heat pump system and directly powers the backup electric, gas, or oil heating source. So essentially, engaging emergency heat stops your heat pump and switches to alternative hardware for heating the home.
Used as Backup Heat Source
The sole purpose of emergency heat is to serve as a secondary heat source when your main heat pump cannot maintain the interior temperature. Usually, this would occur during frigid winter temperatures, an equipment malfunction, or if the heat pump ices over outside. Emergency heat kicks in to prevent indoor temperatures from dropping excessively lower than the thermostat setpoint.
When to Use Emergency Heat
Extremely Cold Temperatures
The most common and appropriate use of emergency heat is when exterior temperatures remain below 30degF for an extended duration, whether it be overnight or for multiple days. If the heat pump struggles to extract enough heat from the outside air, resulting in room temperatures dropping well below your thermostat setpoint, it may be necessary to engage emergency heat.
Signs You May Need Emergency Heat
Here are a few signs that indicate your heat pump could use the supplemental help of emergency heat:
- Indoor temperatures decreasing far lower than your thermostat setting
- Frost accumulation on the external heat pump unit
- Hearing your backup heating system running continuously in an attempt to keep up
In scenarios like these, briefly switching on emergency heat can provide enough temporary heat to take the strain off your backup heating system while still keeping your home reasonably warm. Just don't leave it running for extended durations.
As Last Resort
Before rushing to turn on emergency heat, first ensure your thermostat is set properly and confirm that auxiliary heat is enabled and functioning if available. Emergency heat really should be an absolute last resort for periods when all other attempts to heat the home have failed. Overusing emergency heat unnecessarily will lead to exorbitant energy bills and wear and tear on HVAC equipment.
Pros and Cons of Emergency Heat
Advantages
- Provides supplemental heat when the heat pump can't keep up
- Prevents pipes from freezing in frigid indoor temps
- Maintains barely tolerable interior warmth
Disadvantages
- Much less energy-efficient compared to the heat pump
- Can double or triple heating costs
- Puts strain on backup heating system
Auxiliary Heat
Auxiliary heat is similar to emergency heat in that it provides supplementary heating beyond just the heat pump itself. However, there are a few key differences:
- Auxiliary heat runs automatically when needed, while emergency heat must be manually switched on
- Auxiliary heat only supports the heat pump, emergency heat replaces it entirely
- Auxiliary heat runs for shorter bursts, emergency heat will run continuously
Optimizing Emergency Heat Use
Use Conservatively
Because of the disadvantages of emergency heat, it's crucial to use it sparingly and only when absolutely necessary. Never rely on it as a long-term or primary heat source. Auxiliary heat or repairing the heat pump is better for sustained operation.
Adjust Thermostat
Run your heat pump more efficiently by configuring the thermostat schedule with slight temperature drops when asleep or away. Then program it to automatically bump back up before you wake or return home so emergency heat is rarely needed. A programmable thermostat can optimize heat pump operation.
Regular Maintenance
Well-maintained heat pump and emergency heating systems with annual tune-ups, repairs as needed, and regular filter cleaning are less likely to require emergency heat to pick up slack from a struggling heat pump.
Troubleshooting Problems
Before flipping the emergency heat switch, troubleshoot any underlying issues forcing you to rely on secondary heat. Check your thermostat wiring, heating equipment connections, thermostat battery, and inspect the heat pump itself. Contact an HVAC technician if problems persist to diagnose and professionally service your system.
Knowing when to engage the emergency heat function can save you from utterly frigid indoor temperatures in the peak of winter. But resist the urge to overuse it or risk decreased efficiency, discomfort, huge bills, and overworked equipment. Emergency heat on your heat pump should only be used conservatively as a temporary last resort when all other heating options fail in the bitter cold.