How do i wire nest to this old Lenox
#1
08-02-20, 06:15 AM
How do i wire nest to this old Lenox
Need to figure out how to hook up nest 3rd generation to this thermostat
#2
08-02-20, 07:38 AM
Those old thermostats are a nightmare. Similar, but different one here: Lennox Mercury to Nest
Ideally go to the air handler and see what color connects there to verify connections.
- Lennox - color - Nest
- R - green - O/B
- M - red - Y1
- Y - white - W1
- V - blue - Rc
- F - yellow - G
Ideally go to the air handler and see what color connects there to verify connections.
bricesonn
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#3
08-02-20, 10:33 AM
Group Moderator
bricesonn
voted this post useful.
#4
08-02-20, 02:50 PM
Neither wiring diagram worked. It acts like no power. It says nest won't work with v/vr systems. Might have to give up.
#5
08-02-20, 09:06 PM
Group Moderator
You will need to locate where the transformer is. Some have one inside, some outside and some have both.
Sometimes the nest can be finicky based on the amount of power it can steal.
You may ultimately need to get a C wire to the stat.
Sometimes the nest can be finicky based on the amount of power it can steal.
You may ultimately need to get a C wire to the stat.
#6
08-03-20, 09:03 AM
I do not have a Nest but when I changed my unit out my Venstar t stat REQUIRED a constant hot. Which most of the older single stages t stats did not require. Check behind the t stat and see if you have an extra wire. If you do then you can terminate it on the control board and get the voltage you require.
bricesonn
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#7
08-03-20, 07:45 PM
Group Moderator
The R is constant hot. You mean a Common.
This is an old Lennox system and could use two transformers. They were NOT wired like systems are today and the ID lettering does not match.
This is an old Lennox system and could use two transformers. They were NOT wired like systems are today and the ID lettering does not match.
