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RabbitWhisperer4Fun t1_j9vi189 wrote

There’s one option I haven’t seen below and I realize you already bought the thermostat… BUT! There are some really nice wireless thermostats that don’t require pulling a new wire. What you have REQUIRES pulling a new wire. Thermostats have fairly sensitive electronics and are matched to a graded and measured wire with precisely known resistance. This means that when you turn your thermostat to 70F it will warm the house to 71f…allow up to 3+/- temp. And turn start the furnace at 67F again. If you use the old (most likely solid core 18g copper) wire you will end up a few degrees in either direction or shortening the life of the new thermostat. This isn’t in the instructions and I’m not sure why…maybe Honeywell likes selling new thermostats every few years to the same person? The wiring advice below is good. Do that if you stick with a wired thermostat but the wireless option for about $180 is going to be trouble free and only need a recharge on the 9V lithium battery about every 3 years. Well…THAT is my opinion and like bellybuttons…everyone has one.

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luthiz t1_j9vliiq wrote

Fairly sensitive electronics...? Shortening the life of new thermostat...? What are you on about?

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ghostridur t1_j9w49px wrote

The thermostat determines the temperature swing not the wiring. Most residential stats don't have deadzone adjustment. All a stat does is connect white to red to complete the circuit which starts the heating cycle when it drops below the deadzone temp, and shuts it off after the satisfied (set) temp.

In no way would you want a 1 degree swing, generally you want only 4 to 5 cycles per hour on heating. Short cycling doesn't warm up the heat exchanger and more of your money goes out the vent. My commercial honeywell doesn't allow deadzone adjustment but allows cycle limiting and learns what it needs based on the run times and temps.

Good news, these are facts unlike your unfounded nonsense.

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bird_equals_word t1_j9wjh9n wrote

This is nonsense. 2 wire thermostats turn the heater on or off. There is no analog signal for temperature.

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Valaice t1_j9xh8g0 wrote

Please don't listen to this person, they are completely clueless. Wire is wire when it comes to thermostats. HVAC tech here.

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DirtyPolecat t1_j9wyc7o wrote

There's nothing intrinsic to the wire that has anything to do with temperature control. Thermostats are just on/off dry contact switches that turn on/off parts of the heating/cooling system depending on some internal temperature measuring device, like bimetallic strips in mechanical stats or thermistors in digital ones. You can even do this manually by shorting wires.

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Senior_Cheesecake155 t1_j9ybbjj wrote

Wire resistance what? You understand that wire resistance is going to change based on not only gauge but length, right? Thermostats work the same whether they’re 2’ from the furnace or 200’ from the furnace, both with drastically different wire resistance.

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