[Cesiumxrs286]

Help please,
I was planning on installing a nest thermostat. Watched a bunch of YouTube videos. Read different articles online. Checked the nest website and thought I had enough info to tackle this DIY on my own. Then I opened the HVAC system and the old thermostat. Now I'm super confused because the wires don't match. How can that be?

 

[beenthere]

Probably some of the wires go directly outside. Look for a junction in the thermostat wires. Trace them from the air handler toward the thermostat.

 

[roughneck]

Avoid the Nest thermostat. Lots of problems. Lots of issues. They are marketed as cutting edge, but they are nothing more then a novelty.

 

[Cesiumxrs286]

Avoid the Nest thermostat. Lots of problems. Lots of issues. They are marketed as cutting edge, but they are nothing more then a novelty.

All smart thermostats are novelty though. Just want to make sure I install it right the first time and not have to think about it after that.

Thanks for the junction box info. I guess it goes to the roof before coming to the thermostat. I wonder what my options are now

 

[roughneck]

All smart thermostats are novelty though. Just want to make sure I install it right the first time and not have to think about it after that.

Thanks for the junction box info. I guess it goes to the roof before coming to the thermostat. I wonder what my options are now

Return the nest and look at WiFi options from Ecobee and Honeywell. Both are vastly superior and reliable compared to the nest.

 

[Cesiumxrs286]

All smart thermostats are novelty though. Just want to make sure I install it right the first time and not have to think about it after that.

Thanks for the junction box info. I guess it goes to the roof before coming to the thermostat. I wonder what my options are now

Return the nest and look at WiFi options from Ecobee and Honeywell. Both are vastly superior and reliable compared to the nest.

I get it. Nest isn't the best option out there. I've looked at the other choices. For my home it really just needs to be blowing cold air or hot.That's all I need. I get it there's even cheaper options then the nest to do that too, but here we are box is open and I just need some help.

 

[diyorpay]

There are usually 2 'bundled' wire sets.

One goes to the compressor area. You say 'goes to the roof'. That's not the one you want to follow.

beenthere advised to trace wires from air handler to thermostat. That's the 'bundle' you want to see. Your second pic shows the colors at the thermostat as yellow (and it's jumped to 2 terminals), another yellow, orange, and blue or purple. That's the bundle you want to find somewhere in the air handler area.

Can't see from pic if you have a 'C' terminal at old stat. If you don't, this will be your challenge to get Nest hooked up correctly. Many threads in this forum about that.

First pic at air handler is hard to see if there's a 'C' terminal to tap off to bring to thermostat. If you don't have, it gets complicated.

 

[Cesiumxrs286]

There are usually 2 'bundled' wire sets.

One goes to the compressor area. You say 'goes to the roof'. That's not the one you want to follow.

beenthere advised to trace wires from air handler to thermostat. That's the 'bundle' you want to see. Your second pic shows the colors at the thermostat as yellow (and it's jumped to 2 terminals), another yellow, orange, and blue or purple. That's the bundle you want to find somewhere in the air handler area.

Can't see from pic if you have a 'C' terminal at old stat. If you don't, this will be your challenge to get Nest hooked up correctly. Many threads in this forum about that.

First pic at air handler is hard to see if there's a 'C' terminal to tap off to bring to thermostat. If you don't have, it gets complicated.

Yeah that's where I was confused at the air handler it's 3 wires and at the thermostat it's 4... I've included a diagram

 

[user_12345a]

I get it. Nest isn't the best option out there. I've looked at the other choices. For my home it really just needs to be blowing cold air or hot.That's all I need. I get it there's even cheaper options then the nest to do that too, but here we are box is open and I just need some help.

It's not a question of price, it's a question of the hardware and firmware being over-priced unreliable junk which causes problems.

Get rid of it and get a honeywell or even sensi if you don't want to spend a lot of money.

Based on the wiring it looks like you may have a heatpump and those are best left at a constant temperature in heating mode.

 

[Cesiumxrs286]

I get it. Nest isn't the best option out there. I've looked at the other choices. For my home it really just needs to be blowing cold air or hot.That's all I need. I get it there's even cheaper options then the nest to do that too, but here we are box is open and I just need some help.

It's not a question of price, it's a question of the hardware and firmware being over-priced unreliable junk which causes problems.

Get rid of it and get a honeywell or even sensi if you don't want to spend a lot of money.

I don't really follow your statement. You start of saying it's not about price, but end up talking about price.

We can talk about what is the best model for price ratio somewhere else. That's not why I joined. If you don't want to help that's also fine, but options on the best product isn't going to help me... Nest, Honeywell, sensi, or etc. I'm still going to need to figure out which wires go where period.

Thanks to those that are actually trying to help I really appreciate it! It's going to be 100° the next few days and I would like to try and have this ready for that.

 

[user_12345a]

What I meant is not get something like a ecobee instead of nest because it's overkill for your needs, there are cheaper options than that which don't have major issues like the nest does.

Returning the nest should really be a given - to prevent future problems.

You already got good help on the wiring. The main thing you need is a common - this wire runs between the air handler and t-stat, connects to the C terminal if there is one, if not gets tied to the common side of the transformer.

 

[diyorpay]

The yellow, brown and blue wires you're calling air handler: These leave (exit) the air handler and go to compressor in attic. These are not the blue, orange and 2 yellows from air handler board to thermostat. You have to find them somewhere else in air handler, possibly another board.

Look for some yellow wires coming from direction of thermostat.

Your blue wire on thermostat would normally be green and is for fan. It is probably connected to G terminal on board when you find it. Label your Blue wire at thermostat as 'G' or fan.

Your yellow wire (normally red) on thermostat terminal RH should be labeled 'R' or 'RH'. It is the 24V supply but for call only. It only supplies 24V when thermostat says 'I need power!' to heat or to cool.

Other yellow wire connected to both W and Y should be labeled as 'W' and 'Y' and needs jumping for both terminals. W is heat. Y is A/C. Your physical toggle switch on thermostat for 'heat' or 'cool' determines which. Off position does nothing.

Your missing wire for the Nest is 'C' common wire which is for constant 24V. Digital thermostats (usually with no batteries) especially with wi-fi control need this.

Orange wire may be heat pump related. Do you have a heat pump?

It is possible that the brown wire on your board that you have located is able to be tapped as a 'C' wire but has to be brought to thermostat.

Another suggestion: installers often use a wire bundle from air handler to thermostat but don't use all wires. Remove existing thermostat from wall to better see if there are spare wire(s) going to board that are not being used. One of those (if there) could be used as 'C' wire.

 

[Cesiumxrs286]

The yellow, brown and blue wires you're calling air handler: These leave (exit) the air handler and go to compressor in attic. These are not the blue, orange and 2 yellows from air handler board to thermostat. You have to find them somewhere else in air handler, possibly another board.

Look for some yellow wires coming from direction of thermostat.

Your blue wire on thermostat would normally be green and is for fan. It is probably connected to G terminal on board when you find it. Label your Blue wire at thermostat as 'G' or fan.

Your yellow wire (normally red) on thermostat terminal RH should be labeled 'R' or 'RH'. It is the 24V supply but for call only. It only supplies 24V when thermostat says 'I need power!' to heat or to cool.

Other yellow wire connected to both W and Y should be labeled as 'W' and 'Y' and needs jumping for both terminals. W is heat. Y is A/C. Your physical toggle switch on thermostat for 'heat' or 'cool' determines which. Off position does nothing.

Your missing wire for the Nest is 'C' common wire which is for constant 24V. Digital thermostats (usually with no batteries) especially with wi-fi control need this.

Orange wire may be heat pump related. Do you have a heat pump?

It is possible that the brown wire on your board that you have located is able to be tapped as a 'C' wire but has to be brought to thermostat.

Another suggestion: installers often use a wire bundle from air handler to thermostat but don't use all wires. Remove existing thermostat from wall to better see if there are spare wire(s) going to board that are not being used. One of those (if there) could be used as 'C' wire.

Thanks for all those details. Yeah, I was on a chat with nest support last night and they said it was an air handler. I'm in a condo and that makes sense to me now because I'm guessing the compressor is on the roof somewhere. I don't see any other bundles coming from the air handler area. Is there a way I could tell there is an unused C-wire just by looking at it on the thermostat side?

 

[diyorpay]

https://support.google.com/googlenest/answer/9452748?hl=en

Do you have a heat pump?

Here's a pic of my air handler. Look for similar.

 

[Cesiumxrs286]

https://support.google.com/googlenest/answer/9452748?hl=en

Do you have a heat pump?

Here's a pic of my air handler. Look for similar.

The person I spoke to said it was an air handler. Here is a more zoomed out look and model number if that helps.

 

[Cesiumxrs286]

I also took the thermostat off the wall. I think I found the brown wire from the handler, but it's capped off with a black wire that isn't on the handler

 

[Cesiumxrs286]

I also took the thermostat off the wall. I think I found the brown wire from the handler, but it's capped off with a black wire that isn't on the handler

Could this be the magical c-wire I need?????

 

[diyorpay]

Could be, however, still recommended to find where those wires come from.
Only then will you be sure what's connected and its purpose.
Orange wire usually heat pump related.

 

[Cesiumxrs286]

Yeah, true it would be a gamble to just plug it in hoping that it's the C-wire. it's just interesting that there's an orange and black wire going to the thermostat, but unclear where they come from. Could there be only 2 wires coming down from the compressor on the roof?

 

[diyorpay]

IF, cable 1 goes to compressor... and
there's another cable, cable 2,...
is that where the mystery wires to thermostat are?
Just a guess.
Could be just power.