Hey there!
I see you're getting error code e78 on your Nest thermostat. That can be frustrating, but we're here to help. To troubleshoot this effectively, I'll need some information:
Safety First: Before we delve into troubleshooting, remember to turn off the power to your Nest thermostat at the breaker box. Safety is paramount when dealing with electrical components. If you're not comfortable working with electrical wiring, don't hesitate to reach out to a licensed electrician or HVAC technician.
- Check the wiring: Make sure the W2 wire is securely connected to the correct terminal on both the thermostat and the furnace. You might need to consult your Nest thermostat's manual or Nest support for specific wiring instructions for your model.
- Move the W2 wire: In some cases, the solution might be to move the W2 wire to a different terminal. Again, refer to your Nest thermostat's manual or consult Nest support for detailed instructions.
- Nest Thermostat: If you're seeing this error on your Nest thermostat, it indicates an issue with the wiring, particularly the W2 wire. This wire controls the auxiliary heat source. Here are a couple of things to try:
- Baxi Boiler: For Baxi boilers, error code e78 signifies a problem with the water pressure sensor. This sensor is crucial for the boiler's safe and efficient operation. A faulty sensor can lead to overheating or even a complete shutdown of the boiler. It's advisable to consult a qualified technician to diagnose and fix the issue with the water pressure sensor.
In addition I would like to ask you some additional questions that might help diagnose the cause of error code e78:
What Nest thermostat model do you have? (e.g. Nest Learning Thermostat, Nest Thermostat E)
What's the make and model of your HVAC equipment (furnace or air conditioner)?
When was the last time you did a routine maintenance check on your HVAC system?
In addition to the questions above, here are some other things to consider:
- Have you recently made any changes to your Nest thermostat wiring or your HVAC system?
- Are you seeing any other error messages on your Nest thermostat display?
By gathering this extra information, we can create a more targeted approach to troubleshooting the e78 error code.
Regards,
Brandon.
