Installing a programmable thermostat is not unlike installing any other thermostat for your HVAC system. The key is to get the right thermostat for your HVAC system and to make sure it is wired properly. Many thermostat manufacturers provide detailed installation instructions with their thermostats to make sure you have all the information you need to install the thermostat properly. Sometimes the instructions that come with the new thermostat can be vague or even confusing and that is what we want to help you with here at High Performance HVAC. Please see our other articles for installing thermostats on our other pages to help you with your thermostat installation. Below are some good tips and detailed instructions on installing your new programmable thermostat. And don’t forget after the new programmable thermostat is installed you still have to program it.
The above chart will help you understand the wiring terminals and color designations for a heat pump. If you are installing a the programmable thermostat for a boiler it should only require two wires. It is a two wire thermostat installation. This is for a battery powered thermostat and the two wires are only for the switching on and off of the boiler for heating.
Wiring your programmable thermostat for boiler or furnace control with only two wires will work just fine except you will need to keep replacing the batteries on a regular basis. If you want to have the thermostat powered by the transformer the wiring needs to be as in the following graphic:
Whereas the common wire from the transformer goes into the thermostat to provide a complete 24 volt circuit for thermostat power. For an air conditioner the wiring should be as follows:
These are the basic wiring diagrams for installing a programmable thermostat. There are some other combinations for wiring a programmable thermostat but the information here will cover 90% of the combinations most people need. If you have something different or unique email us using the contact form and describe to use what you have. We will respond to you with some follow up questions and ask you to send us some photos of what you have. Then we will respond to you with our advice on how to wire your thermostat.