# Nest install, extra wires left over from previous thermostat



## vestaviascott (Mar 7, 2009)

Just installed Nest thermastat. We ended up with two wires left over that the Nest kit did not have labels for, s1 (a red wire) and s2 (a white wire). Since there was no apparent place for these wires on the Nest connector plate, I left them unconnected in the bundle and installed the nest. 

Nest appears to be working fine with no complaints, however, after a couple hours running and heating fine, the furnace started blowing cold air for a brief period of time. One of the downstairs ceiling vents even had dripping water condensation all over it.

Any ideas what might be happening? I see no reason the system should be blowing hot and cold air intermittently.


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## Bob Sanders (Nov 10, 2013)

vestaviascott said:


> Any ideas what might be happening? I see no reason the system should be blowing hot and cold air intermittently.


Probably because of the "extra" wires you left unconnected 

What kind of heating/cooling system do you have and is it a multi stage system?

Post pictures of the old thermostat connections as well as the connecting board on your heating/cooling system


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## vestaviascott (Mar 7, 2009)

rheem Classic 80 5ton single stage

I'll post pics. Thx for the help.


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## beenthere (Oct 11, 2008)

S1 and S2 are usually remote temp sensor terminals. Your old stat may have used a remote indoor sensor to control temp, or it may have had an outdoor temp sensor. Is your system a dual fuel system.


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## roughneck (Nov 28, 2014)

What thermostat was removed? S1 and 2 are sensors as listed above. X2 on the duel fuel.


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## vestaviascott (Mar 7, 2009)

Furnace is a Rheem Classic Quiet 80, Natural Gas Forced Air Unit. Thermastat was a Honeywell Vision.

Here's a pic of the original thermastat connections










Here's the Nest wiring harness with pre-existing wiring (2 wire bundle with red and white in one bundle and the rest in the other). Red and white were connected to S1 and S2 respectively.









Blue was connected to W O/C even though we have a furnace and not a heat pump

Not sure where black was connected.

Please help! Its cold down here in Bama tonight.

Thanks in advance.


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## roughneck (Nov 28, 2014)

Whyd you remove a visionpro for a Nest? Honeywell is arguably the best stat on the market. 
Is there an outdoor sensor?


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## Bob Sanders (Nov 10, 2013)

You're missing a W1 which is first stage heating. W2 is second stage heating. It's not normal to have second stage heat and not have any first stage heat (for forced air, gas). Are you sure that white wire belongs in the W2 slot?

This is not wired correctly given a single stage gas furnace.

Post pictures of these wire connections at the furnace.


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## jimn (Nov 13, 2010)

Did you call nest? There phone support is ver good.


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## Bob Sanders (Nov 10, 2013)

vestaviascott said:


> Blue was connected to W O/C even though we have a furnace and not a heat pump


You say "BLUE" was connected to the 'W o/b'. Meanwhile the blue is connected to C (common). I'm assuming that was a mistake and you meant orange?

My guess is that the orange is your first stage heat, but that should be confirmed by checking the wire colors at the furnace.

It looks to me like someone wired a gas furnace as if it was a heat pump. Maybe there was a heat pump there before and the Rheam replaced it? Either that or it's a dual fuel... (gas backing up a heat pump?)


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## vestaviascott (Mar 7, 2009)

We just moved in. It appears to be duel fuel. Heat pump outside in rheem condensor unit. Gas burners have been on all night in basement furnace. Temp still stuck mid 60. Nest set to 75. I'll call nest today. 

I removed the furnace filter and felt the air inside. It's not warm at all. Should it be?


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## beenthere (Oct 11, 2008)

Rheem heat pumps energize the RV in heat mode. So the blue wire needs to be connected to the O/B terminal, and O/B needs to be energized for heat.


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## Bob Sanders (Nov 10, 2013)

beenthere said:


> Rheem heat pumps energize the RV in heat mode. So the blue wire needs to be connected to the O/B terminal, and O/B needs to be energized for heat.


I don't think this is a heat pump.



vestaviascott said:


> Furnace is a Rheem Classic Quiet 80, Natural Gas Forced Air Unit. Thermastat was a Honeywell Vision.


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## beenthere (Oct 11, 2008)

Bob Sanders said:


> I don't think this is a heat pump.





> Heat pump outside in rheem condensor unit.


He said its a Rheem.


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## Bob Sanders (Nov 10, 2013)

The quiet 80 comes up as a 2 stage gas furnace.


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## beenthere (Oct 11, 2008)

Bob Sanders said:


> The quiet 80 comes up as a 2 stage gas furnace.



He said heat pump outside "in Rheem condenser". The quiet 80 is a furnace. It is not a condenser.


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## Bob Sanders (Nov 10, 2013)

Ahh.. Okay. Thanks.

Didn't see that post.


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## roughneck (Nov 28, 2014)

If this is duel fuel, and the old visionpro was being used as the control, the nest will not work. I don't recall it having hybrid compatibility.


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## zappa (Nov 25, 2011)

beenthere said:


> He said heat pump outside "in Rheem condenser". The quiet 80 is a furnace. It is not a condenser.


If that's the case his A/C and heat would be running at the same time. No wonder they are having trouble heating the house.


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## Bob Sanders (Nov 10, 2013)

roughneck said:


> If this is duel fuel, and the old visionpro was being used as the control, the nest will not work. I don't recall it having hybrid compatibility.


I believe nest supports dual fuel.


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