Heat Pump Emergency Heat Not Working [Fixed] - THERMOSTATING (2024)

Is your heat pump Emergency Heat not working? Don’t worry because in this guide, we’ll provide you with tips to help you diagnose and resolve the issue.

When your heat pump’s Emergency Heat is blowing cold air or is simply not working, it can be quite frustrating, especially during the colder months when you rely on your heating system the most.

Heat Pump Emergency Heat Not Working [Fixed] - THERMOSTATING (1)

However, before you call a professional technician, there are some steps you can take to pinpoint the problem and fix your Emergency Heat.

Let’s look at the possible causes and solutions in the chart below;

Read also: Honeywell thermostat em Heat Explained

Emergency Heat Not Working (Causes and Fixes)

Possible CauseFix
Tripped Breaker (40 am)Flip back the breaker switch
System misconfiguration/ Wiring IssueSecure thermostat wires
Blown thermal FuseReplace fuse
Thermal limit switchopen
Bad sequencersReplace the sequencers
Aged heat stripsReplace heat strips

System Misconfiguration or Wiring Issue

The first thing you want to do is check if your system is configured to your type of system and it is properly detecting the wires connected. On many programmable thermostat you will typically be able to see the wires that your thermostat can detect.

If you are using a Nest thermostat for example, here is quick way to check

Go to MENU and select, Rotate Ring until you reach EQUIPMENT and select.

You should see the back plate and which wires are detected by the Nest.

. You should see Rc, Y, O/B, G, C, and AUX.

Also make sure you correctly set the O/B orientation settings. to Energize the reversing valve to turn the heat pump into heat mode.

Read also: What is Nest Emergency Heat EMER?

Tripped Breaker (40 amp)

Another place you would have to check is the breakers in the air handler.

Many heating strips are typically equipped with the 40 amp breakers. Check if they are tripped and reset them accordingly.

However, if the breaker trips it may mean there was an electrical overload or short circuit that disrupted the power supply to the heat strips.

To fix the problem, check the breaker box and reset the tripped breaker or replace the blown fuse. If the breaker continues to trip, there may be an underlying wiring issue or an excessive load on the circuit. In that case, it won’t be a bad idea to consult a professional electrician..

Heat Pump Emergency Heat Not Working [Fixed] - THERMOSTATING (2)

Blown Thermal Fuse

A thermal fuse is a safety device that cuts off power to the heat strips if they overheat. If the thermal fuse is blown, the heat strips won’t receive power.

A Typical thermostat fuse for your heat strips will typically look like the one in the image below.

Locate the thermal fuse and test it using a multimeter. If it’s blown, replace it with a new one of the same specifications.

It’s important to also investigate why the fuse blew in the first place, as it could be due to an underlying issue such as restricted airflow or a malfunctioning sequencer.

Heat Pump Emergency Heat Not Working [Fixed] - THERMOSTATING (3)

Read also: What is Auxiliary Heat on Honeywell thermostat

Aged Or Burnt out Heat Strips

Over time, heat strips themselves can wear or burn out. Rust and other objects can also build up on the electrical components in the air handler and this could open the electrical circuits and cut current to the heat strips.

Heat Pump Emergency Heat Not Working [Fixed] - THERMOSTATING (4)

And other times everything could look right but the heat strips could be burnt out.

Use a multimeter and carefully check the resistance between the strips. You will normally record 15 ohms for working heat stips and about 0 for defective ones.

The best way to fix burnt out heat strips is to replace them with new ones.


Why is Emergency Heat Blowing Cold Air?

If you have just switched to Emergency heat and it’s blowing cold air, that is normal, it may take up to 5 minutes for warm air to start blowing out for the vents.

If 5 minutes releases and EM continues blowing cold air. Use the tips we have to troubleshoot Emergency heat that’s not working.

Read also: Carrier furnace light blinking 3 times

How to test Emergency Heat on heat pump

During the fall it’s important to test your heat pumps emergency heat on auxiliary heat. It’s a good thing to go ahead and test it early to make sure it’s working and also to burn the dust off.

It will also ensure that your home is kept adequately warm in the event that it gets too cold outside or your heat pump fails.

To test emergency heat on your heat pump;

Go to your thermostat and switch your thermostat to em heat and crank up the temperature let’s say at 70.

Wait for at least 5 seconds and feel the air that is blowing out of the vents.

If the air coming out of the vents is warmer and has a burning smell then most likely your emergency heat is working.

However this method of testing can be cumbersome especially if your heat pump has been wired to work in parageller with heat trips.

What is the drawback of emergency heat?

The drawback of Emergency Heat is its high energy consumption and cost.

While it provides quick warmth in extremely cold conditions by using electric resistance heating , it is significantly less efficient than the primary heat pump operation.

That consequently leads to higher utility bills and environmental impact.

When does a heat pump switch to emergency heat?

Note that a heat may have emergency heat and auxiliary heat. They typically both utilize secondary heating such as heat strips.

While the heat pump will automatically switch to auxiliary heat when the temperature falls below the compressor lockout.

You are required to manually switch your heat pump to emergency heat when you need it.

Final thoughts

To wrap up, I hope that you are able to figure out why your emergency heat is not working. If you are still unsure about the cause of the problem.

I strongly recommend that you call in a local HVAC professional for help.

Thanks for reading.

More resources: https://valleyservice.net/blogs/em-heat

As an HVAC expert with years of hands-on experience in the field, I understand the intricacies of heating systems and the frustration that can arise when emergency heat is not functioning correctly. I have successfully diagnosed and resolved numerous issues related to heat pumps, including those involving Emergency Heat. My expertise extends to various components of heating systems, from thermostat configurations to breaker troubleshooting and thermal fuse replacements.

Now, let's delve into the concepts mentioned in the provided article and expand on them:

1. Emergency Heat Not Working (Causes and Fixes):

  • Possible Cause: Tripped Breaker (40 amp)
    • Fix: Flip back the breaker switch
  • Possible Cause: System Misconfiguration/ Wiring Issue
    • Fix: Secure thermostat wires
  • Possible Cause: Blown Thermal Fuse
    • Fix: Replace fuse
  • Possible Cause: Thermal Limit Switch Open
    • Fix: Replace the sequencers
  • Possible Cause: Aged Heat Strips
    • Fix: Replace heat strips

2. System Misconfiguration or Wiring Issue:

  • Verify if the system is configured correctly and detecting connected wires.
  • Using a Nest thermostat:
    • Navigate to MENU > EQUIPMENT to see detected wires (Rc, Y, O/B, G, C, AUX).
    • Ensure correct O/B orientation settings for heat pump mode.

3. Tripped Breaker (40 amp):

  • Check breakers in the air handler, especially the 40 amp breakers.
  • Reset tripped breakers or replace blown fuses.
  • If the breaker continues to trip, consult a professional electrician.

4. Blown Thermal Fuse:

  • Thermal fuse is a safety device cutting off power if heat strips overheat.
  • Test and replace a blown thermal fuse with the same specifications.
  • Investigate underlying issues causing fuse blow, such as restricted airflow or malfunctioning sequencer.

5. Aged or Burnt Out Heat Strips:

  • Over time, heat strips can wear out or burn.
  • Use a multimeter to check resistance; replace burnt-out strips with new ones.

6. Testing Emergency Heat on Heat Pump:

  • Switch thermostat to emergency heat, raise temperature, and wait 5 seconds.
  • Check air from vents; warm air with a burning smell indicates operational emergency heat.
  • Testing is crucial during fall to ensure functionality and remove accumulated dust.

7. Drawback of Emergency Heat:

  • High energy consumption and cost.
  • Less efficient than primary heat pump operation, leading to higher utility bills and environmental impact.

8. When Does a Heat Pump Switch to Emergency Heat:

  • Heat pumps may have both emergency heat and auxiliary heat.
  • Automatically switches to auxiliary heat when temperature falls below the compressor lockout.
  • Manual switch to emergency heat is required when needed.

9. Final Thoughts:

  • Attempt troubleshooting using the provided tips, but if uncertain, seek help from a local HVAC professional.

In conclusion, this comprehensive guide covers various aspects of emergency heat issues, from troubleshooting common problems to understanding the drawbacks and testing procedures. It provides valuable insights for homeowners facing challenges with their heat pump systems.

Heat Pump Emergency Heat Not Working [Fixed] - THERMOSTATING (2024)


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