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ecobee M5A Smart Wi-Fi Thermostat User Guide

Less common thermostat wires:  
Any unnecessary or spare wires not needed can be safely taped off or wrapped around the wiring  
bundle and tucked back into the wall.  
Label  
S, S1 or S2  
Description  
S terminals are for outdoor temperature sensors. ecobee thermostats obtain weather data over Wi-Fi so S  
wires are not necessary.  
The L wire can be used to power indicator lights on older thermostats. ecobee thermostats feature an LCD  
display so the L wire is not necessary.  
L
Most HVAC systems feature a single fan speed. In multi-speed systems, fan speed is either controlled by the  
furnace control board or the thermostat.  
G2, G3, GL,  
GM, GH,  
FAN1, FAN2,  
FAN3  
I have a multi-speed system. How can I tell if it is controlled by the furnace control board or by my  
thermostat?  
· If your multi-speed system is connected to your current thermostat by a single G wire, fan speed is set by  
the furnace control board.  
· If multiple G wires connect to your thermostat, your thermostat manages fan speed.  
ecobee thermostats support the former type but not the latter.  
If you’re installing an ecobee thermostat in a multi-speed system with multiple G wires running to your old  
thermostat, use the table below to match your preferred fan speed with the correct wire:  
On heat pump systems, the O and B wires tell the compressor when to switch between heating and cooling  
your home.  
O and B  
If you have a wire labelled B but do not have a separate wire labelled O, connect it to the ecobee  
thermostat’s O/B terminal.  
If you see O and B as separate wires in your current setup, we recommend booking a pro near you to install  
your ecobee.  
Worth a look: Occasionally, the wire labelled B may in fact be the common wire (C), which is needed to  
power an ecobee thermostat.  
A wire connected to the W3 terminal on your current thermostat indicates that you have a three-stage  
furnace. ecobee thermostats do not support three-stage furnaces. Workarounds are to connect a jumper  
between the W2 and W3 terminals on your furnace’s control board or add in a “Delay on Make adjustable  
timer” to control 3rd stage.  
A wire connected to the Y3 terminal on your current thermostat indicates that you have a three-stage  
cooling system. ecobee thermostats do not support three stages of cooling. Workarounds are to connect a  
jumper between the Y2 and Y3 terminals on your furnace’s control board or add in a “Delay on Make  
adjustable timer” to control 3rd stage.  
W3  
Y3  
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Toronto, ON M5A 0B5  
ecobee.com  
GeneralDetails
Nameecobee M5A Smart Wi-Fi Thermostat User Guide
MakeEcobee
LanguageEnglish
FiletypePDF (Download)
File size2.48 MB
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ecobee M5A Smart Wi-Fi Thermostat User Guide