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AR15.COM
10/30/2015 7:17:18 PM EDT
So I'm looking to replace my conventional temp control with a Nest unit.  I'm currently running a "dual fuel" setup for heating.  I have a Heat Pump and a Gas Furnace.
I'm looking at the wiring on my current control (see below).
When I use Nests compatibility tool, it says yes but recommends a professional install because of the dual fuel setup.  I think if I was an easier setup, they provide the correct diagram for wiring.  So do I need a professional install or can I do this myself?  Looks pretty straight forward in terms of matching my the corresponding conenctions.







My connections below are: C, R, G, O/B, Y, W2 and E.


From what I was reading on Nests website, the W2 and E essentially get converted into 1 connection and then the setup tells it when to fail over to the other system.  







1.) Do I connect it to the current W2 & E wire (yellow) to just the W2/Aux connection or w1 on the Nest unit?  


2.) To setup the fail over to the emergency heat, the FAQs, said it's just now a setting in the Nest setup to do this.  Is that correct?


3.) Anything else I need to consider?


4.) original question. Do I really need a professional or just make the corresponding connections and setup my fail over for the emergency heat and be done with it?















 

 
10/31/2015 12:23:55 PM EDT
[#1]
I hate it when they dont use the standard color coding  The colors match what terminal they go to Red-R Yellow-Y1 White-W1 Green-G   what is so hard about this?

You will have to know how the change over from the heat pump to fuel is done. Is it done in the indoor unit or by the tstat?
10/31/2015 8:30:38 PM EDT
[#2]
So connected all up.  While going through the testing, it all "worked".  Heat pump, air and gas.  I ended up setting the crossover to 30 degrees. I guess we will see.
11/12/2015 4:53:28 PM EDT
[#3]
Did you set your heat pump wire into the o/b terminal then use the w2/aux for your secondary heat ?
11/12/2015 8:52:27 PM EDT
[#4]


Quote History
Quoted:



Did you set your heat pump wire into the o/b terminal then use the w2/aux for your secondary heat ?
View Quote
Heat pump to o/b and gas furnace to W1.  I saw one of their articles that said that aux heats should just use W1.  So I did that.
 







Page21 talks about dual fuel systems.  When o/b is used its treated as heat 1 and you use the pro setup to specify the 2nd fuel.  It says that w1, w2 or * is treated as 2nd fuel.