![Customer (and friend of mine) wanted a smart thermostat to control a waste oil furnace with a gas furnace as a second stage/backup. It's ugly but effective....Also works to isolate line voltage Customer (and friend of mine) wanted a smart thermostat to control a waste oil furnace with a gas furnace as a second stage/backup. It's ugly but effective....Also works to isolate line voltage](https://i.redd.it/2iewmufird881.jpg)
Customer (and friend of mine) wanted a smart thermostat to control a waste oil furnace with a gas furnace as a second stage/backup. It's ugly but effective....Also works to isolate line voltage
![EconoHome Non-Programmable Thermostat for Home - Heat & Cooling Temperature Control - Easy to Install - Digital Thermostat for Central Gas, Oil, Electric Furnaces, Single Stage Systems - Walmart.com EconoHome Non-Programmable Thermostat for Home - Heat & Cooling Temperature Control - Easy to Install - Digital Thermostat for Central Gas, Oil, Electric Furnaces, Single Stage Systems - Walmart.com](https://i5.walmartimages.com/asr/d304c99c-8d90-4a74-a771-02c356de35ef.ed0a8adc96c79e6692f500b9c5ab0f9f.jpeg?odnHeight=768&odnWidth=768&odnBg=FFFFFF)
EconoHome Non-Programmable Thermostat for Home - Heat & Cooling Temperature Control - Easy to Install - Digital Thermostat for Central Gas, Oil, Electric Furnaces, Single Stage Systems - Walmart.com
![Honeywell Home RTH6580WF 7-Day Programmable White Thermostat with Wi-Fi Compatibility in the Smart Thermostats department at Lowes.com Honeywell Home RTH6580WF 7-Day Programmable White Thermostat with Wi-Fi Compatibility in the Smart Thermostats department at Lowes.com](https://mobileimages.lowes.com/productimages/b7e6f078-e8ff-4e39-8933-611f31c4ce50/49267138.jpg?size=mpdhi)
Honeywell Home RTH6580WF 7-Day Programmable White Thermostat with Wi-Fi Compatibility in the Smart Thermostats department at Lowes.com
![Honeywell Home Wi-Fi Smart Color 7-Day Programmable Smart Thermostat with Color-Changing Touchscreen Display (2-Pack) RTH9585WF10042PK - The Home Depot Honeywell Home Wi-Fi Smart Color 7-Day Programmable Smart Thermostat with Color-Changing Touchscreen Display (2-Pack) RTH9585WF10042PK - The Home Depot](https://images.thdstatic.com/productImages/f84ac9aa-b522-4e35-a707-04492a8e71bd/svn/metallic-honeywell-home-programmable-thermostats-rth9585wf10042pk-a0_600.jpg)
Honeywell Home Wi-Fi Smart Color 7-Day Programmable Smart Thermostat with Color-Changing Touchscreen Display (2-Pack) RTH9585WF10042PK - The Home Depot
![6 things you should do before you replace your current thermostat with a smart thermostat – Smart Thermostat Guide 6 things you should do before you replace your current thermostat with a smart thermostat – Smart Thermostat Guide](https://smartthermostatguide.com/wp-content/uploads/2018/07/old-thermostat-tips-for-replacing-with-smart-thermostat.jpg)
6 things you should do before you replace your current thermostat with a smart thermostat – Smart Thermostat Guide
![Honeywell Home Wi-Fi Smart Color 7-Day Programmable Smart Thermostat with Color-Changing Touchscreen Display (2-Pack) RTH9585WF10042PK - The Home Depot Honeywell Home Wi-Fi Smart Color 7-Day Programmable Smart Thermostat with Color-Changing Touchscreen Display (2-Pack) RTH9585WF10042PK - The Home Depot](https://cf-images.us-east-1.prod.boltdns.net/v1/jit/66036796001/9910f654-c33b-4d81-bf33-3fb50a0b220c/main/1280x720/40s74ms/match/image.jpg)
Honeywell Home Wi-Fi Smart Color 7-Day Programmable Smart Thermostat with Color-Changing Touchscreen Display (2-Pack) RTH9585WF10042PK - The Home Depot
![King Electric Hoot WiFi Line Voltage Programmable Thermostat, 120/208/240V, Single Pole K901-B - The Home Depot King Electric Hoot WiFi Line Voltage Programmable Thermostat, 120/208/240V, Single Pole K901-B - The Home Depot](https://images.thdstatic.com/productImages/3e568043-e72a-45ce-a68f-890b80344114/svn/black-king-electric-programmable-thermostats-k901-b-64_600.jpg)
King Electric Hoot WiFi Line Voltage Programmable Thermostat, 120/208/240V, Single Pole K901-B - The Home Depot
![hvac - How do I connect a WiFi thermostat to my furnace's primary control? - Home Improvement Stack Exchange hvac - How do I connect a WiFi thermostat to my furnace's primary control? - Home Improvement Stack Exchange](https://i.stack.imgur.com/P8htrl.png)