This guide will walk you through removing your old thermostat and connecting the thermostat wiring to the new one. If you haven’t removed the old one yet, wait!
There’s important information here about what to do with the thermostat wiring when disconnecting it from the old unit. It will help you avoid confusion when wiring the new unit.
There are three common reasons to replace a thermostat.
If your HVAC system is having any of these problems, there’s a possibility the thermostat is the cause:
Secondly, you might have to upgrade the control if you’ve installed two-stage or variable-capacity equipment and your current thermostat wiring doesn’t support it.
The tool list for replacing a thermostat is short:
The new control must match your system’s capabilities. If you don’t know these, pull the cover off to check the thermostat wiring on the old unit. Yellow wires are typically for AC. If there is one yellow wire, it’s a single-stage AC; Two yellow wires indicate a two-stage or variable-capacity unit. White wires are for the furnace, and the same principle of one or two wires applies. There might be one or two wires not connected to a terminal. They are for HVAC components or functions your system doesn’t have, such as a heat pump reversing valve typically connected to the orange wire.
When shopping for thermostats, their packaging or the control’s online description should list what type systems each supports. With the preliminaries out of the way, here are step-by-step thermostat wiring instructions. Please also look at the below extra tips extracted from the steps.
There is an industry standard regarding the color of the wires used for each function, yellow for cooling and white for heat, for example. It is surprising how often the standard isn’t followed. This is why labelling and taking a picture of the thermostat wiring on the old unit are essential. When installing the new unit, connect the wires to the same terminal on the new unit they were connected to on the old thermostat, regardless of color. If you rely on color, and the standard was not followed, your system won’t run. The worst-case scenario is that you might short the control board on the furnace or air handler, and that is a pricey repair.
If your HVAC system doesn’t work properly once the new thermostat is installed, make sure each wire is secure in its terminal. If problems persist, turn off the system and get assistance from a local HVAC professional.
Replacing a thermostat is DIY-friendly. Just go slow, take a picture and label wires. Hiring an HVAC technician for the work will cost $75+, and that’s money that should stay in your pocket.
An easy way to save your family and friends that cash is to share this thermostat wiring guide with them. They’ll appreciate the tips! After you replace your thermostat, feel free to chime in here on how the job went for you. It will encourage others to tackle thermostat wiring rather than spending money on pro installation.
Image from pixabay.com.