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2 Wire Thermostat Connection for an EcoBee Wifi Thermostat on an old Weil McLain Model H-4 Boiler
        
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                    Michael_Zaborskis                
                
                    Member Posts: 6                
            
                        
            
                    I could not find much information on the Internet dedicated to this topic, so I am sharing what I for others who endeavor into such a task. The objective herein was to replace an old 2 wire mercury thermostat with a modern ecobee3 thermostat, and in doing so provide a new common line for the wifi thermostat utilizing the existing 2 wire design.  I made use the FAST-STAT common maker system for this installation. Attached is the wiring diagram, with modifications,  as a resource for others in their endeavors.                 
                
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            Comments
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            excellent info, thanks for taking the time to figure it out.Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 
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