Categories: hvac

Auxiliary vs. Emergency Heat

As temperatures drop, people rely on thermostats to ensure that the heat pump produces enough heat to keep them home warm and cozy throughout the colder months. Unlike gas stoves, which generate heat with the flame of a burner, heat pumps operate differently by extracting heat energy from the outside air. It concentrates this air and circulates it throughout the interior of the house. 

During winter, you can also switch the heat pump to one of two settings to maintain the room temperature. Depending on the outside temperature, the thermostat can change the heat pump to one of two options: auxiliary heating or emergency heating. While the differences between these two can be too complex for most homeowners to understand, it’s best to at least have a basic understanding of their operation.

What Is Auxiliary Heat?

Auxiliary heat is a function on your thermostat that automatically activates when outdoor temperatures are cold – most likely around 30 to 40 degrees depending on the efficiency of your heating system. When temperatures plunge below freezing, your heat pump may not be able to draw sufficient heat to keep the temperature in your space at your desired setting and liking. This is when the heat strips, which are your heat pump’s secondary heat source, kick into gear. Take note, however, that when this backup function is utilized, you may notice a slight increase in your electricity bill.

Although it may seem like it isn’t much you can do when your thermostat says the auxiliary heat is on, remember that if the temperatures are incredibly frigid outside, it can be too much for your unit. This will require you to change your settings to keep the auxiliary heat from turning on at this time. As a guide, here are tips to remember for your heat pump during this season:

  • Call a heat and air condition service professional if your thermostat indicates that aux heat is running even after outside temperatures reach 40 degrees.
  • Only turn your heat up two degrees at a time to avoid using auxiliary heat.
  • Avoid switching the emergency heat setting unless it’s an emergency. Experts note that your aux heat works with your secondary heat source and your home’s heat pump. Turning on emergency heat means you’re relying entirely on the secondary heat source, which is a lot more expensive than running aux heat. To understand more about emergency heat, read further.

What Is Emergency Heat (EM)?

The EM function acts like auxiliary heat, but the setting on the thermostat has to be manually switched on and off. As mentioned, emergency heat should only be used when your outdoor unit cannot pull heat at all – a circumstance often caused by a broken component or a malfunctioning system. This will activate the heat strips, which will supply 100% of the heat to your home until the heat pump is repaired. Similar to your aux heat, utilizing the emergency heat setting for extended periods is not typically recommended as it will notably raise your energy costs.

Thus, this must only be used whenever necessary like when your home is not reaching the set warm temperature due to your deteriorating outdoor unit.

How Your Heat Pump Functions With the Emergency Heat

Typically, a heat pump works by pulling in heat from the outside. Its setting’s emergency heat may switch automatically during brief periods when the outside temperature gets too chilly. As stated, your heating system will then use the secondary system with your standard heating. Meanwhile, manually activating the EM heat sets a different chain of events – like bypassing the primary heat pump, forcing it into an aux mode.

From Where Does Emergency Heat Come?

Many may not know, but this could be a backup gas furnace, an electric heat strip, oil or a hot-water system. This also means that if your emergency heat is electric, you can expect much higher prices when running your EM system. 

Which Is Better for Your Home?

The automatic setting when temperatures drop should be auxiliary heat. This will only activate if your heat pump can no longer extract enough heat so that it can still contribute to keeping the indoor temperatures comfortable while minimizing demand from its secondary heating strips. If emergency mode is activated, the heat pump function won’t be used at all; instead, your system will rely on its electric heating coils. These consume much more energy, which means you get higher monthly utility bills.

Did You Accidentally Turn on Your Emergency Heat?

If you’ve accidentally turned on your EM heat, don’t worry. Just like turning it on, you can deactivate your emergency heat with the switch.

Maintaining Your Heat Pump

Ensure that your equipment stays functional for your convenience throughout the year as seasons change. Here are upkeep tips you can keep in mind.

  1. Ensure your indoor air filters are cleaned or replaced at least every two to six weeks.
  2. Double-check whether there’s no damage to the outdoor pipe covering, dirt clogging the outdoor coil or oil drips at or below the piping connections at the unit.
  3. Keep debris and snow away from the outdoor unit. Do not forget to prune back your plants to at least 18 inches from all sides of the heat pump to allow proper airflow and servicing.
  4. Polish your outdoor coils regularly. If they get dirty, use a heavy-duty degreaser and hose them down.
  5. Schedule professional service at the manufacturer’s recommended interval, or call your trusted local technician for an inspection or if you see any problems to avoid spending a lot more in the future.

Do you need a heating or air condition repair service? Turn to EZ Air Conditioning and Heating for superior residential and commercial HVAC services. We also specialize in attic insulation, duct cleaning and home automation. Give us a call at (210) 429-9186, or fill out our contact form to get an estimate. We look forward to working with you and ensuring that you stay comfortable all year long.

Jonathan Hernandez

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