Before you buy a programmable thermostat you must make sure you know exactly what type of HVAC systems you have. Cheap programmable thermostats tend to have limited compatibility. Some of the best thermostats such as a Honeywell digital thermostat, for people with 2 stage heating and 2 cooling or a heat pump with auxiliary heat are the Honeywell RTH7500D and the Honeywell RTH8500D 7 day programmable thermostats.
Once you have selected and bought a suitable programmable thermostat you will need to install it. Installation of a programmable thermostat is not a difficult procedure but it is imperative that you read the instruction manual first to make sure you know what you are doing.
Next, turn off the air-con, heater, fan etc. at the circuit breaker. You must make sure that all the HVAC systems are off otherwise you will give yourself a shock and possibly blow the transformer.
Then remove the front cover of the old thermostat and note down the anticipator setting. Then unscrew the old thermostat and gently remove to reveal the wires behind. They should be colored. There should be a red, yellow, white and green wire and they should be attached to terminals on the old thermostat labeled according to color. The red is sometimes labeled ‘RH’, ‘RL’ or ‘R’. If the wires are not colored then use the terminals on the old thermostat to adduce their color and use masking tape to identify the color of each wire.
Once you are satisfied you have got it right un-attach the wires and wrap them around pencils. Then you can remove the sub-base of the old thermostat and drill holes for the new sub-base. After that thread the wires through the new sub-base and attach them to the correct terminals on the new digital programmable thermostat. Use the color designations to help.
Then screw the new programmable thermostat to the wall and check the heat anticipator setting is the same as with the previous thermostat.
Finally put the cover on the Honeywell digital thermostat, switch the HVAC back on at the circuit breaker and press reset on your new programmable thermostat. You should now be ready to enter your programs for the week and start saving money.

