Alternate Heat Stage 2 Nest (2024)

FAQs

What does heat stage 2 mean on a Nest? ›

What is meant by Stage Two heating? When the thermostat on a dual-stage furnace reads “Stage 2,” it implies that the furnace is operating at the higher setting, giving you 100 percent of its capacity. Usually, the lower setting of a dual-stage furnace is sufficient to provide household comfort almost 80% of the time.

If a dual fuel system is installed, the Nest Thermostat will display “ALT. HEAT” or “ALT. HEAT STAGE 2” if the alternate heating sources are engaged. Auxiliary heat will only turn on when the outdoor temperature is below the auxiliary heat lockout temperature.

Note: If Alt heat (not AUX heat) appears, your Nest Thermostat E is configured to work with a dual fuel system. You won't find an option to use Emergency Heat, but your thermostat will automatically use alternate heat when needed.

The supplemental heat is also referred to as second-stage or back-up heating, with first-stage being the Heat Pump only. Emergency Heat is when you use your supplemental heat (2nd stage) by itself, without the use of your heat pump (1st stage heat).

Stage 2 simply means that thermostat has engaged second stage of heating because temperature has droped more than 2 degrees below set temperature.

Two-stage furnaces are more expensive up front, whereas single-stage models are generally cheaper because they have fewer parts to maintain and repair. With that said, two-stage furnaces make better use of energy because of their two motors, making it more cost-effective to run.

The first stage (low fire) is the primary one that runs about 75% of the time or more. The second stage (high fire) will typically activate when it's icy cold outside. It will also turn on if the thermostat senses it needs to raise the temperature more than two degrees. We'll return to our BTU example.

If the set point is greater than 2 degrees from the current room temperature, it will activate stage 2 cooling. Once it the room temperature gets within 1 degree, it will switch back to stage 1 cooling.

The Emergency Heat or Auxiliary Heat setting is the second stage of your heating system that is used when the temperature is too low for the heat pump to be able to remove heat from outside, typically below 35 degrees Fahrenheit.

It can also include gas, oil, or even hot-water backup systems too. These supplemental heating sources are known as “second-stage” or “back-up” heating. The “first state” heating is the heat pump itself. Emergency heat is when you use your “second-stage” by itself without using your “first stage”.

Why does Nest say heat in 2 hours? ›

Your Nest thermostat will estimate the Time-to-Temperature in increments of five minutes. If it's less than ten minutes until the temperature you've selected is reached, the display will read, "less than ten minutes." If it's more than two hours, Nest will read "IN 2+ HR."

Heat pumps do not operate as efficiently when temperatures drop to between 25 and 40 degrees Fahrenheit for most systems. A heat pump works best when the temperature is above 40. Once outdoor temperatures drop to 40 degrees, heat pumps start losing efficiency, and they consume more energy to do their jobs.

Two-stage heating means the furnace has two levels of heat output: high for cold winter days and low for milder days. Since the low setting is adequate to meet household heating demands 80% of the time, a two-stage unit runs for longer periods and provides more even heat distribution.

Auxiliary heat isn't a bad thing; in fact, it can be extremely necessary to your comfort and well-being, especially in the event of extreme cold weather. However, auxiliary heat uses a good deal of energy, which leads to an increase in your energy bill.

Auixiliary Heat will turn on automatically when heat can no longer efficiently transfer heat from the outside air to heat pump. This is when the outside is around 35-40 degrees and the indoor temperature is around three degrees cooler than the thermostat setting.

Two-stage heating means the furnace has two levels of heat output: high for cold winter days and low for milder days. Since the low setting is adequate to meet household heating demands 80% of the time, a two-stage unit runs for longer periods and provides more even heat distribution.

The heat pump will cycle on and off at low speed — first stage — for the majority of the year, until it gets really cold or hot out and needs to jump to high speed — second stage — to keep up. The heat pump will automatically jump between stages in response to the temperature that you set on the thermostat.