Google Nest Wiring Help needed please

[needhelpplease]

I need to understand how to wire our Nest thermostat with the following house wiring.  It is not matching the instructions and I have tried to search for something similar here, so I apologize if I missed something.  I appreciate the help.  

We have the following wires coming from the wall:

-          Red

-          Green

-          Yellow

-          Blue

-          White

The Nest unit has ports for :

-          Y

-          C

-          W

-          G

-          R

-          OB

Please advise as to the recommended wiring diagram that I could use.  Also, my current manual thermostat has a “jumper wire” from W to Y.  Thank you.

[CoolingWizard]

In order to help you best, we need to see the picture of the old thermostat to determine what color wire was attached to which HVAC control terminals of the old thermostat . Keep in mind the thermostat does not know how to see the colors. As for the control system:

R is the Power In 24 VAC

C is the Power Common 24 VAC

Y is the output to call for Compressor to turn on. 

W is the output to call for Heating such as a gas furnace. 

G is the output to turn on the Blower Fan

OB is out to change the Heat Pump Reversing Valve. Think of this, as changing the mode from heating and cooling, or changing the road from Cooling to heating.

The AC Cooling Wizard

[needhelpplease]

[CoolingWizard]

Your Red Wire goes to R, you can ignore the jumper between Rc and Rh. You currently do not have a Power Common wire.

I cannot see the labels for the wires on the right side.
 I’m betting the Green wire is in G.

I see a white wire that loops between Y and something else. Is the wire 
there is a blue wire. Is the white wire connected to something?

The AC Cooling Wizard

[needhelpplease]

I hope that photo transmits ok. 

Currently wired:

House red wire to R port

Green wire to G port

Yellow wire to Y port

Blue wire to B port

Jumper from W to Y

Thank you so much for any assistance!

[needhelpplease]

White wire coming out of the wall is not currently being used.

Blue wire from wall is connected to B port currently.

But there is no B port on Google Nest.

Finally there is a jumper between Y and W.

And also the Nest has an OB port and I don't have an OB wire? 

Also the Nest calls for a C wire and I don't have a C wire that I know of?

So current wiring is:

House red wire to R port

Green wire to G port

Yellow wire to Y port

Blue wire to B port

Jumper from W to Y

Hope that makes more sense??

Thanks again.

[CoolingWizard]

What this tells me is that you actually have a heat pump. Now that particular thermostat is not totally compliant with a heat pump. That’s why there’s a jumper between the W and the Y. This is how you’re going to hook up your nest thermostat.

Put the Red wire in R or Rc.

Put he blue wire in the OB

Put the Yellow wire in Y or Y1.

Put the green wire in G

Set your equipment up as a Heat Pump.

when it comes to a heat pump, there are two types of heat pumps in the world. One is called an O type, and the other one’s called a B type. By default a heat pump is either going to be a heating unit or it’s going to be a air conditioning unit. And the reversing valve is energized to switch it from that to the opposite. Rather than making a thermostat with that had an O connection and a B connection. They combined it into the O/B connection. Then your software in the thermostats will be configured to tell it when to energize the OB wire.

The AC Cooling Wizard

[needhelpplease]

Great, thank you.  What about the White Wire?  Does it connect anywhere in this set up? thanks.

[needhelpplease]

And do we need the jumper any more?

[CoolingWizard]

The Nest does  not need any jumpers.  The white wire might be a conductor that can be wired up for the Common Power since it is not being used.  You will need go to the air handler and see if the the white wire is connected to anything yet. If not, you can connect to the C terminal and the C in the nest. 

The AC Cooling Wizard

[needhelpplease]

The white wire is not connected to the current thermostat at all.  Is it possible that it is not needing to be connected to the Google Nest at all then?  

[CoolingWizard]

The Nest thermostat charges better when it has a C wire.  With certain older systems, the Nest can use the Y or the W wire to sort of go through a back door to reach the transformer Common side.  If you get an error about power, you might need to venture into the air handler and hook that white wire to the common terminal. 

The AC Cooling Wizard

[needhelpplease]

I connected everything the way you suggested on your earlier message and it blew hot air with the AC set to a low temperature.

I was not able to explore anything further around the white wire that wasn't connected before because I don't know what you mean by "venture into the air handler" -- as I don't know where the air handler is  -  nor do I know what a "common terminal" is once I were to find the air handler.   So I was only able to set it up with the configuration that you suggested up until that point in the conversation -- after which I asked about that white wire.  And like I said, it just blew hot air even though it was set to cold air.  I am not sure what that means? Is that related to the mysterious currently unconnected white wire do you think?  Thank you, again.

[CoolingWizard]

From your old thermostat we know that what you have is a heat pump. Heat pumps come as two different default mode systems. They are typically known as O models or B models.  O models default to be Heaters, and B Models default to be Cooling. Your Heat Pump is an O model. Therefore the reversing valve on the heat pump must be energized to get cooling.  You say when you choose AC cooling, you get warm air now then if you set your Nest to Heating, and you set the temperature desired at say 2-degrees higher than the current room temperature, you will get cold air out of your system. This will happen because your reversing valve mode is backwards.

If your system is blowing hot air when you call for cooling, the reversing valve mode needs to be changed.  You need to go to the thermostat, tap it, go into SETTINGS, go to EQUIPMENT, then tap to enter, the display will show you the wires it detects, choose CONTINUE,  now you will see a list of system types, choose HEAT PUMP and you see  Heat Pump reversing valve setting. You should see a blue check mark next to B. The default is O and it is the one we should have a check mark next. Simply choose O and tap. The check mark will move from B to O.   Now choose DONE. 

By the what part of the country do you live in?  I ask this because your heat pump system does not appear to have Auxiliary Heating.  

The AC Cooling Wizard 

[needhelpplease]

We followed the instructions you provided (thanks) and we got a message when we got to the part where it lists what wires are detected.  It indicated Y-G-R-*OB, but underneath that, it said "Note: N260" -- which says we need a properly functioning C wire.  It wouldn't let us progress past that screen to get to the "Heat Pump" screen you mentioned, so we were basically stuck.  We also did try to connect the white wire to the C port in hopes that might be the C wire, but nothing happened, so my guess is that wire is not connected at the HVAC.  In reading more information on the N260 message, it appears we need a C wire or a Google Nest Power Connector.  It sounded like it would be easier to install a Nest Power Connector than try to connect the C wire, so we ordered one of those.  I am hoping that will be as easy as it sounds (probably not lol) and that will solve our problem perhaps.  We live in Arizona so that is why we don't have to worry about needing a lot of heat.  It is more the AC that is critical to us!  Thank you for all of your help.  I am hoping that the Nest Power Connector is the solution!

[CoolingWizard]

The nest power connector would only be required, If your system did not have a spare, unused wire conductor in your cable. Since you have a white wire that is not being used, it could be assigned to the C terminal at each end. You have two choices here you can go locate the indoor unit and make the connection yourself or you can hire an HVAC company to come in and tell them to connect the white wire to the seat terminal in your air handler. It’s on the other hand you have an all in . If on the other hand, you have a all in one packaged unit, the connection is rather simple to make at that unit.

AC Cooling Wizard

[needhelpplease]

Our HVAC unit is on our roof and it is very difficult to get up there as you need an extra long ladder and there is a high parapet wall to get over once you get up there.  Therefore, we did not go on the roof yet and we really aren't sure what the connections will look like once we do.  It seemed smarter to go with the Nest Power Connector just to make sure that we could actually do it ourselves and that we had all that we needed.  You are right that if the C connector is up there just not connected, then we probably didn't need it.  We are just wanting to be ready for whatever we find and be able to just go up there once and get it done.  We didn't want to have to go up there more than once!  Thank you again for all of your help.

[CoolingWizard]

Since you say the HVAC system is on the roof, you have what is called a “packaged” unit. This means that all the electrical and all the control system is all contained within that one unit. So if you were going to use a nest power connector, you would have to go up there and connect it to the control board. However,  you won’t have to use a Nest power connector since you have a spare wire. Sometimes they refer to these as rooftop units. (RTU). 

If I were you, I would call around to different HVAC companies and tell them you need them to go onto your RTU Heat Pump and connect a conductor to the Common for your smart thermostat.  Ask them what they would charge you to do that. It will take a technician all of 5-Minutes, once on the roof, to make the connection you need.  

What part of the country you live in? I am in southern most part of California. 

The AC Cooling Wizard

[needhelpplease]

Thank you for the additional information. We are in Phoenix.  I think at this point, we will give it a try ourselves, and then if we still can't make it work, we will get some professional help.  It would have not been a big issue if it wasn't on the roof!  Thank you for all of the time that you have spent providing advice. It is appreciated!!

[CoolingWizard]

If you are going onto the roof, please let me know so I can assist you. On the roof will be a power disconnect. Open it and turn it off or pull the connector out.  Now look at the unit and see where the power and thermostat cable enter the unit. That is where the connection to the white wire will be needed.  You will need a 5/16 nut driver to open the panel. Contact me at 4422834692 if you decide to hook the white wire up yourself. 

The AC Cooling Wizard

[needhelpplease]

That is so kind of you!  Thank you.  The plan is to wait for the Nest Power Connector to arrive (I already ordered it today, but I am sure it will take a few days to arrive with regular shipping) and then take that up on the roof -- just in case we end up needing it.  But we will try to do it with the existing white wire 1st.  Then only if that doesn't work, we will try the Nest Power Connector.  I think you are right that we probably won't need it.  But we may as well wait for it at this point.  And have it on the roof just in case so we can just do that once. Thanks for the heads up on the 5/16 nut drive -- we do have one of those.   I will keep you posted.  Thank you, again!

[zoeuvre]

Hi needhelpplease,

Great! Sounds like a plan. Once you have an update, please let us know, as we would be happy to assist and make sure you are good to go.

I appreciate your help, @CoolingWizard. 

Thanks,

Zoe

[Dan_A]

Hey there,

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

Best,

Dan

[Jake]

Hey needhelpplease,

I wanted to check in and see if you managed to see Zoe's post. Please let me know if you have any questions from here. I would be happy to assist, and make sure you are good to go.

Best regards,
Jake

[Jake]

Hey there,

I wanted to check in with you, and let you know that I will be locking the thread in 24 hours.

Best regards,

Jake

[Theone202]

Please help on how to wire google nest thermostat

need to j ow where to place the two W wires

 

[zoeuvre]

Hi Theone202,

Thanks for posting here in the Community forum. I’d like to take a look at this for you. 

Since Nest Thermostats only cater to one wire per terminal and your current thermostat wiring configuration shows that there are two wires connected to the W, can you help me with the photo of your furnace control board where the other end of the thermostat wires are connected?

I’ll look forward to your response. 
 

Best, 

Zoe