This is when the outside is around 35-40 degrees and the indoor temperature is around three degrees cooler than the thermostat setting. When your system reverses itself to defrost the coils, it automatically turns on the radiation strips in order to keep providing your home with warm air. Call Parks Heating & Cooling today at (704) 313-1443 or contact us online to schedule a heating service with our team. If you look at the backside of Nest Thermostat, you can see labels (O/B , AUX/E) – which means this thermostat is compatible with heat pumps (O/B) and also compatible for heat pumps with aux/emergency heating (AUX/E). **Note that if your Emergency Heat light is on but your thermostat is NOT set to Emergency Heat, this is an indicator there’s a problem with your heat pump and you should call for advice and service. Exactly as the name implies, in emergency situations only. Moving heat- In heat mode, your heat pump is like an air conditioner working in reverse to pull heat from the outside to inside your home (the opposite of how it works in cooling mode). This is known as running on “auxiliary heat.” Generally, this can’t be controlled manually, but is instead switched over to automatically when your system either senses that it has been running for too long, or too much ice has built up on the outdoor coil and it needs to begin a defrost cycle. If you’ve taken even a slightly longer glance at your thermostat, you may have noticed it has a couple of extra heat settings: one called “auxiliary heat” and one called “emergency heat.” While most people know these two settings exist, few people actually know the difference between them. Virtually all heat pump stats, no matter the age, have both an Emergency switch and an automatic Aux mode (although with older stats, the control logic that activates Aux may be poorly implemented). AUX heat turns on to keep you warm. Electric heat strip - This electric heat strip is auxiliary heating (or “aux heat” as it shows up on your thermostat). When do I use it? Because consumers have many more auxiliary heat options to work with for augmenting heat pumps, this allows them to experience a winter or two in a milder climate zone without the feature before committing to the extra investment, whichever one it may be. Otherwise, just keep your thermostat set on “heat.” There is no temperature to switch it over to emergency heat, even if your heat pump is running constantly due to cold weather. What Is the Difference Between Auxiliary Heat & Emergency Heat. I'm getting an E33 error, and Nest thermostat is telling me that I can only have one auxiliary heat wire. In order to further understand what these modes do, it’s important to know how a central heater works. Yes, as ridiculous as it may sound, your heater can literally freeze, usually at temperatures of around 40 degrees Fahrenheit or below. If there's a wire in the W1 connector, make sure it says AUX heat. But what happens when you still need heat? In this video we go over the heat pump balance feature in the programming of the NEST thermostat. Having Emergency Heat on can and will be more expensive to run. Simple: during this period, your system turns on a series of electrical radiant heat strips that can still provide you with heat, but while consuming more energy. So on this blog, the experts at Parks Heating & Cooling take a look at both of them and explain the important differences between the two. Your heat pump only is the “first stage” heating. Auxiliary heat is the electric heat strip in your air handler that is supplemental heat. When turned on, your compressor and heat pump shut off entirely and your radiation heat strips in your system turn on. This is why it is only used in an emergency situation. However, at temperatures in the 20s and 30s or below, your heat pump may not be able to produce heat at all because there simply won’t be enough in the ambient air to extract. Both of these wires are needed for Emergency Heat. When the temperature inside your home drops about two or three degrees below the temperature the thermostat is set to, auxiliary heating kicks on to help warm your home more quickly. Generally, the NTE will use the heat pump if it needs to heat three degrees or less and auxiliary heating if it needs to heat up four or more degrees. I have a Lennox heat pump with electric emergency/aux heat, I also have a humidifier. And in that case, you should also call a professional for help.. So a convenient way to check if a thermostat model is compatible with heat pumps is to check its wiring labels. Emergency Heat Hello, It's going to be really cold here in Alabama the next few nights and I'm trying to decide what is the best approach to handle the cold nights. The unit outside your home is a heat pump and the unit inside the home is the auxiliary heating system. And that’s not necessarily a good thing. HEAT" or "EMERGENCY HEAT" instead of "HEATING" (as appropriate) when it is using the electric heating coils. In the usage of a standard heat pump, users often encounter the terms heat and emergency heat. Note: In some cases, your heat pump’s AUX heat could be a gas furnace, but since Phoenix typically has mild winters, some AZ homeowners will have electric resistance as their AUX heat. heat except when really needed" intelligent algorithm. ** Auxiliary Heat. That means it has to reverse the flow of refrigerant again in order to allow the hot fluid to flow through your coil and melt off any condensed or frozen snow or ice. Emergency heat is the same thing as auxiliary heat. Both systems are actually controlled by the device’s thermostat. Now I keep on getting alerts that the Aux heat is running. The Emergency Heat Switch on a Heat Pump confuses a lot of people. Different systems and thermostats have different ways of determining when the second-stage heat comes on to assist the heat pump, but it is always done automatically. Aux on the thermostat stands for auxiliary heat. The Emergency Heat setting locks out the heat pump and forces the auxiliary heat source (in Minneapolis homes, it’s most likely a gas furnace) to provide 100% of the home’s heating. Sign Up for Our Brand-New Parks Newsletter. Aux heat still doesn't start until the difference between set temp and current temp is 4 degrees. Short answer: You should only set your heat pump’s thermostat to “emergency heat” when your heat pump stops heating altogether. After making these settings, the Nest "home screen" (showing the current temperature and whether it's heating" will show "AUX. All these are great questions! You’d only use this setting when the heat pump malfunctions or is damaged and fails to provide heat . They will work in tandem when the temperatures drop to those cold numbers. The thermostat will sense this and turn on electric heat strips automatically turning on the “AUX” heat light. The outlet temperature with and without Aux heat depends on outdoor temp, wattage of electric heat strips and CFM setting. Knowing the difference between your heat pump’s auxiliary heat and emergency heat will help address the question from above. I guess the only difference is that AUX is an ‘indicator’ on your thermostat that you are running the heat strips when the switch is set to HEAT. So the signal will either come from the White Wite on W2 or the brown wire on E to turn on the heat strips. During freezing weather, the outdoor heat pump will be too cold to quickly heat your home, which is when the auxiliary heating system would kick on. Auxiliary heat uses electric resistance heating, which is much less efficient than your heat pump. Emergency Heat is typically triggered when it is 35°F and below outside. The diagram on Nest indicates that W1 and W2 are Aux heat, and OB is "heat pump". Your auxiliary heat supplements your heat pump’s heat––it doesn’t replace it. It does not support virtually any other kind of heat pump, such as a 1-stage heat pump with separate 2-stage furnace heating (dual fuel) or a 2-stage heat pump with/without AUX heat. These supplemental heating sources are things such as the electric resistance heating at the indoor unit, gas, oil or even hot-water back-up systems. The emergency heat setting has to be manually switched on and should only be used in temperatures below 30 degrees. Auixiliary Heat will turn on automatically when heat can no longer efficiently transfer heat from the outside air to heat pump. This indicates that Nest is using its "avoid aux. Most of the time, you won’t even notice the switch has happened unless you look at your thermostat and see that the “AUX” light is turned on. Auxiliary heating turns on automatically to help heat your home more quickly if the temperature drops suddenly. The important thing to remember is that “AUX” heat is fast and dependable but it’s also more expensive than heat … Thus,when your heater has been on for a few hours, your system will have to defrost itself in order to continue functioning. Types of AUX heat (and why it matters) Heat pumps have 2 forms of AUX heat: Electric resistance (default) Gas furnace; The electric resistance option is like the electric coils you see inside your toaster. First “Auxiliary Heat”, “Strip Heat”, “Emergency Heat”, “ Radiant Heat ” are all used to reference the same heating mechanism; your electric heat strips that come with a heat pump. Only run your system in this mode when you truly need it to avoid damaging your central system. 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