Installing wifi thermostat to boiler system

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Old 11-04-20, 07:42 AM
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Installing wifi thermostat to boiler system

Have a pretty basic Honeywell digital thermostat hooked up to my cottages gas
boiler system ( No AC) and would like to replace it with the Honeywell RTH6580WF smart thermostat. The existing wiring it connected to R and W no extra wires in the wall and the thermostat is battery powered, is a C wire needed and do I need any other connections from the furnace.
 
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Old 11-04-20, 07:55 AM
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Yes, a C wire is required. See manual: https://www.honeywellstore.com/store...thermostat.pdf Here is another option that doesn't require a C wire, but it is not WiFi enabled: Honeywell TH6100AF2004
 
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Old 11-04-20, 08:07 AM
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Hi, yes you will need a 3rd conductor, it maybe best to pull a new 18/3 thermostat cable from the boiler to the Stat, post some pics of your boiler controls and we can assist with the connections, good choice for the Stat.
Geo🇺🇸
 
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Old 11-04-20, 06:30 PM
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Electronic thermostats are powered with 24 volts AC on terminals C and RH.

There is a an alternative to installing new 3 wire cable.

Near thermostat install a 120 volt - 24 volt adapter and connect to C and RH. Existing two wires still go to RH and W.

It is an easy way to upgrade older home that have thermostats on 2nd and 3rd floors.

https://www.amazon.com/s?k=120+volt+...ref=nb_sb_noss

No other connections are need from boiler unless there is a fan on system.
 

Last edited by doughess; 11-04-20 at 08:19 PM.
 

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