Wiring compatibility

[erwinespi]

Hi everyone,

                       Can you help me what wiring do I need to follow.  I’m just a little confused. I have a heat pump. Everything is electric. Thank you in advance. 

 

[CoolingWizard]

Your current thermostat handles the Auxiliary Heat differently. Here is how you will wire your Nest Learning Thermostat. 

R - Red Wire to Nest Rc

B/C - Dark Blue wire to Nest C

O - Orange Wire to Nest O/B.

Y1 - Yellow Wire to Nest Y1

G - Green Wire to Nest G

W1 - White Wire to Nest W1

AUX - Black Wire to Nest W2/AUX

I hope that this helps you. 

AC Cooling Wizard

[Patrick_Caezza]

@CoolingWizard 

The Black wire connected to the right AUX1 terminal is not AUX heat. It probably controls either a humidifier, dehumidifier or something similar. The yellow wire is supplying 24V to the left AUX1 terminal.

[erwinespi]

@Patrick_Caezza what do you suggest for me to wire it properly? Thanks

[CoolingWizard]

It still might be Auxiliary Heat @Patrick_Caezza , this is a Heat Pump so it mignt require an inspection or a Nest Pro installation. 

AC Cooling Wizard

[erwinespi]

@CoolingWizard so the directions you sent will work right? 

[CoolingWizard]

We need to see your furnace and look for the auxiliary heat or if there is a Humidifier attached. Your system will work as I have stated.  

AC Cooling Wizard

[erwinespi]

@CoolingWizard I did wired it per your directions. So far it’s working ok. On the initial set up, I’m not sure if I should put single or dual  fuel system. I have a heat pump and electric furnace. Not sure why it’s showing that my alt. heat source is gas. 

 

[CoolingWizard]

Your system is not a duel fuel.  Your system is all electric.  Duel fuel is electric and natural gas, or propane, or healing oil.  

You can change the equipment system in SETTINGS > EQUIPMENT and scroll to Heating, and change the heating type to electric heat pump. Then your W2 will be auxiliary heat 

AC Cooling Wizard

[erwinespi]

@CoolingWizard I tried to change the setting but I don’t see the option to change the heating type to electric. It only allows me to choose just these options: Forced air, in-floor radiant, radiators and more info. 

[CoolingWizard]

Ok, I see the problem. You have a the Nest Thermostat and not the Nest Learning Thermostat. I am not as familiar with the basic nest model.  It might be in Nest Pro sub menu.

AC Cooling Wizard  

[erwinespi]

@CoolingWizard I do have the Nest learning thermostat. The $250 one at Bestbuy. I returned the basic Nest due to incompatibility with the Nest app and sensor. 

[CoolingWizard]

Then you should be able to go to SETUP > EQUIPMENT > CONTINUE > CONTINUE > HEAT TYPE, and select ELECTRIC then select FORCED AIR followed by DONE.

AC Cooling Wizard

[erwinespi]

It doesn’t go to that electric option. After the choosing heat type, it goes to forced air then that’s it. I actually did a full reset to start over but then when I went to select the single fuel, it won’t let me choose it and asking to hire a professional. The only choice was to select dual fuel in order for me to proceed to compete the set up. 

[CoolingWizard]

Ok, you are ok. Let’s take one more step.   Go to SETTINGS > EQUIPMENT > CONTINUE > CONTINUE > PRO SETUP > CONTINUE. You will now see the back plate with colored wedges. Green are ok, Yellow mean they are connected but not functionally defined. You rotate ring to a yellow wedge and select it. Then define its function. For example W2 is Auxiliary Electric Heat.  In Pro Setup, you change any active wire and change its function.  

AC Cooling Wizard

[erwinespi]

So I changed the W1 and W2 to electric. What’s next? I also have a Nest learning thermostat upstairs which I had no issue with that setting it to single fuel. Will that be ok that I have the downstairs as dual fuel setting and upstairs as single fuel? Or keep them both at a dual fuel even though I’m all electric and just change the wiring function like what you said? 

 

 

[CoolingWizard]

We need to take a closer look at that Black Wire. It was powered by the R with a yellow jumper wire.  Remove the Black wire from W2 for now, and put the W1 wire into W2. Whatever that black wire is being used for, it was receiving constant power.  So it’s either going to be a humidifier or an other type of device. What is confusing me is why send the power from the air handler to the thermostat and send it right back on the Black Wire.  We need to go to the air handler and look for where that black wire is connecting to.  We need to go to the air handler and look for where that black wire goes because whatever it is it’s constantly needing power and why it gets it from the thermostat I don’t know. 

AC Cooling Wizard

[erwinespi]

 @CoolingWizard I don’t understand why it shows a brown wire connected to W2. I’ve checked at the wall and what’s connected is the black wire. I don’t know why it’s showing a brown wire in the diagram. Any insights? 

 

[CoolingWizard]

Do not worry about the color of wire Nest displays. It just using standard colors and just uses a different color for each connection.  The point is on your old thermostat the Whit Wire was in W1. This wire should have been placed in W2. The black wire coming out of you wall is not to be on W2. That black wire was powered by the Rh/Rc by a yellow wire jumper.  So we need understand what this black wire is connected to in your air handler. 

AC Cooling Wizard

[erwinespi]

@CoolingWizard How can I find that? I know how to access the air handler in the attic. But what exactly do I need to open and check to find out more info on that black wire? I don’t think I have a humidifier/dehumidifier system installed. On my breaker box, it shows I have AC and two furnace. Not sure if these infos can give us more idea. 

[CoolingWizard]

Normally if you have 2-stages of heat, the second stage would be attached to W2. On the old thermostat the terminal labeled AUX1 is controlling that black wire.  Your other choice is to get the old thermostat go into its program setup and see how AUX1 is defined.  

AC Cooling Wizard

[erwinespi]

@CoolingWizard But technically are my wirings ok? Leaving it as is will it cause trouble? I have tested out the system and use alternate heat also. The heat pump outside doesn’t run if I switched it to alt. Heat which is what supposed to be doing and runs the indoor furnace for alt heat. I just don’t have the option to do heat pump balance on the app. 

[erwinespi]

On my old thermostat, I have an emergency heat function. With nest, I couldn’t find that option. 

[erwinespi]

@CoolingWizard Where should I put the black wire? 

[CoolingWizard]

For now what you can do is just take it back in the hole to keep it out of the way so it doesn’t touch anything else. Any more thoughts about going in the attic and looking to see where the black wire goes just asking?

AC Cooling Wizard

[erwinespi]

I haven’t checked yet. I’m not sure how to open the wiring at the air handler. So what do I do with the upstairs thermostat? Do I put the white wire to W2 as well? 

[erwinespi]

I haven’t got a chance yet. So what will I do with my upstairs wiring? I also have a nest learning hooked up. Do I change the white wire to W2 also? 

[CoolingWizard]

@erwinespi , the upstairs wiring should match the downstairs.  The upstairs does not have a black AUX1 wire so no need to tuck it away.  The W2/AUX is where it goes. 

AC Cooling Wizard

[erwinespi]

@CoolingWizard Not sure how to open the air handler but I got a picture of the board. Not sure if this helps. 

 

 

 

[CoolingWizard]

I am sure you realize that this is your zone controller.  There should be wires leaving this controller going into the inside of the air handler. If you look on the left side the Dark Blue Block is labeled EQUIPMENT and this set of wires goes to the inside of the air handler.  Additionally, the Dark Blue Blocks on the right side are the two thermostat landing points. I see the Black wire  seems to go off to the right somewhere.  

AC Cooling Wizard

[erwinespi]

@CoolingWizard Finally got a chance to check the wiring inside the air handler. Not sure which to take but I took multiple shots. Hopefully this would clear up my wiring concerns. TIA. 

 

 

 

 

 

 

 

[Jake]

Hey erwinespi,

Thanks for the help Patrick_Caezza, and CoolingWizard.

I wanted to follow up and see if I could be of any help. Please let me know if you are still having any trouble from here, as I would be happy to take a closer look and assist you further. 

Best regards,
Jake

[erwinespi]

@Jake So I had it wired already and it’s working fine so far. I’m not sure though if I chose the right setting on the fuel system. I have a heat pump and electric furnace. Is that considered as dual fuel system? I’ve seen various answers all around. Please help. TIA. 

[erwinespi]

Thank you @CoolingWizard   I also have another thermostat upstairs in my house but all runs to 1 unit with zoning capability. Can you help me figure out the wiring for this? See pic. I’m planning to get just the Nest smart thermostat. Not the learning. Will this be compatible?

 

Thank you again! 

[CoolingWizard]

Hello @erwinespi , this is a fairly straight forward installation for a heat pump.  Your control wires being used are 

C - Dark Blue wire to Nest C

R - Red Wire to Nest R

W1 - White Wire to Nest W

OB - Orange Wire to Nest *

G - Green Wire to Nest G

Y1 - Yellow Wire to Nest Y

AC Cooling Wizard