Switching on humidifier leads to very short cycling of heat pump

[royjonker]

C-wire in place, humidifier hooked up. All ok when humidifier switched off. Go into 5sec cycling as soon as it gets switched on.

Funny thing is that we had same thermostat Gen2 before, all working fine. I just copied the wire hookup.

[kcruzgonzalez]

Hello, royjonker. 

Thanks for reaching out to our Nest Community. We are so happy to assist you with your questions about the Nest Thermostat Gen 2.

To assist you in the best possible way, I would like to know if you can send us a photograph of the wiring of the Google Thermostat so we can identify and provide you with the best assistance for your questions.

Please keep me posted. I'll look forward to your response.

Regards,

Kevin

[royjonker]

Here is the wiring, copied from our previous Gen2 installation.

[royjonker]

Looking at it again, no idea why the white wire is in W2. ??

[kcruzgonzalez]

Hi royjonker,

Thank you for your response. And for sharing with us the photograph of your current wiring in your system, I will try to help you in the best way.

Okay, let's try adjusting those cables. Please connect the white cable to the W1 port and the yellow cable to the W2 port. Once that's done, turn your thermostat back on and see if the issue is resolved. Let me know what happens!

Regards,

Kevin

[royjonker]

Hi. This change causes an error message. 'Y1 wire not detected. Heat Pump requires a Y1'.

[kcruzgonzalez]

Hi royjonker,

Thank you for your response. I will try to help you in the best way.

Thank you very much for your reply. The next thing we will do is return the yellow cable to Y1, and the only one we will change now will be the brown cable that is in Y2. We will move that one to port W2, and the white one should always be in W1. Let me know if you get any errors, and I will continue to help you.

Regards,

Kevin

[royjonker]

Still checking if this works or not. Fort now, no error messages. 

One question though: when the thermostat show Equipment Detected, it never show the white wire (currently in W1). Could this simply be my problem? 

[royjonker]

Sorry, not working. I switched the wires around as suggested. Heating seemed to work just fine, until I switched on the humidifier in the app. Heating stopped immediately, and then every 30s the outside fan tries to get going for 10s. 

As soon as I switched the humidifier to off again, the heating came back on nicely.

[royjonker]

In the Equipment detected photo, the humidifier wire is yellow (so, two yellows). Weird question maybe, but any chance that yellow and black wires got swapped somehow?

[kcruzgonzalez]

Hi royjonker,

Thank you for your response. Let's work together for a solution.

I'm very sorry to hear the issue hasn't been resolved yet. Thank you for the photos and information. I agree, it is strange that the thermostat hasn't recognized the cable change. To make sure everything is properly configured, let's try a factory reset on the thermostat itself without changing the cables back. Leave the cables in the configuration I previously advised, and then perform the reset. We'll see if the problem persists afterward.

Let me know how it goes and keep me posted.

Regards,

Kevin

[royjonker]

As you can see in the last photo, the white wire in W1 was not detected. I reinserted it properly. It now shows up, but I get the message 'can only have one Aux. wire'. So, it looks like having both white in W1 <and> brown in W2 is too much. 

[royjonker]

No luck, unfortunately. Did the full reset, app re-connecting, etc. Heating working just fine, as long as the humidifier is off. Switch it <on>, heating stops, and outside fan start very short cycling, as before. Sorry!

[kcruzgonzalez]

Hi royjonker,

Thanks for all the information you've provided and for your patience as we've tried to troubleshoot this. I really appreciate you taking the time to share the photos and details of the wiring.

At this point, I highly recommend contacting a professional Nest pro technician or installer. They have specialized knowledge of these systems and can diagnose the problem on-site. They'll be able to trace the wiring, identify any potential conflicts, and ensure your humidifier and thermostat are working together correctly. This is the most efficient way to get your system up and running reliably.

I understand this might not be the answer you were hoping for, but I want to make sure you get the best possible support to resolve this issue quickly and safely. A qualified technician will be able to pinpoint the problem and get your system working as expected.

Let me know if you have any further questions.

Regards,

Kevin

[royjonker]

Thanks again for all the help! Will try getting a technician here.

[royjonker]

Technician found that there was incorrect wiring in the hookup of the humidifier. All good now, thanks for help.

[kcruzgonzalez]

Hi royjonker,

That's fantastic news! I'm so glad to hear the technician was able to pinpoint the issue and correct the incorrect wiring. It's always reassuring when a problem is resolved, especially when it involves electrical systems.

You're very welcome for the assistance. I'm happy we could point you in the right direction. If you have any further questions or encounter any other issues, please don't hesitate to reach out again.

Regards,

Kevin