1 Gas Heat THERMOSTATS

2 Thermostat A thermostat is a control that is activated by changes in the surrounding air temp.

3 Mercury thermostat Has mercury inside which is considered a hazardous material which. Mercury was used because it stays liquid at room temperature. Not as sensitive as a programmable. Has a heat anticipator. Can only set 1 temperature at a time. Has mercury inside which is considered a hazardous material which. Mercury was used because it stays liquid at room temperature. Not as sensitive as a programmable. Has a heat anticipator. Can only set 1 temperature at a time.

4 Mercury Bulb Thermostat

5 Snap Action Thermostat No mercury. Inexpensive. Accurate, but not as sensitive as a digital thermostat. Has a heat anticipator. Can only set 1 temperature at a time.

6 Snap Action Thermostat

7 Digital Thermostats No mercury inside. Operated by a circuit board and sensor. More sensitive to temperature change- up to ½ a degree. Depending on the brand and model of t-stat being installed, you can set more then 1 temperature. No mercury inside. Operated by a circuit board and sensor. More sensitive to temperature change- up to ½ a degree. Depending on the brand and model of t-stat being installed, you can set more then 1 temperature.

8 Common wiring terminals on all basic thermostats RC = 24v power for cooling RH = 24v power for heating Y = cool W= heat G = blower RC = 24v power for cooling RH = 24v power for heating Y = cool W= heat G = blower

9 Common wiring terminals on all higher end thermostats RC/RH= power (24v) Y1= stage 1 cool Y2= stage 2 cool W1= stage 1 heat W2= stage 2 heat G=fan O= reversing valve ( found on heat pumps) C= common RC/RH= power (24v) Y1= stage 1 cool Y2= stage 2 cool W1= stage 1 heat W2= stage 2 heat G=fan O= reversing valve ( found on heat pumps) C= common

10 Common wire colors used for wiring components RC/RH = Power (24v) = red G = Fan= green Y1 = stage 1 cool= yellow Y2= stage 2 cool= blue W1= stage 1 heat= white W2= stage 2 heat= brown O- reversing valve= orange C = Common= black RC/RH = Power (24v) = red G = Fan= green Y1 = stage 1 cool= yellow Y2= stage 2 cool= blue W1= stage 1 heat= white W2= stage 2 heat= brown O- reversing valve= orange C = Common= black

11 Heat anticipator A device that will shut down the heating circuit, prematurely of the set point, so the system does not over shoot the set- point temperature. The set-point is the temperature the thermostat is set too. A device that will shut down the heating circuit, prematurely of the set point, so the system does not over shoot the set- point temperature. The set-point is the temperature the thermostat is set too.

12 Setting a heat anticipator Take your meter to the t-stat and set it to amps. –Jump out your heating circuit (R and W) –Wrap your jumper around your amp probe 10 times –Read your meter and divide by 10 –This is your heat anticipator set-point Sometimes this information can be written on unit information sticker. Take your meter to the t-stat and set it to amps. –Jump out your heating circuit (R and W) –Wrap your jumper around your amp probe 10 times –Read your meter and divide by 10 –This is your heat anticipator set-point Sometimes this information can be written on unit information sticker.

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