by Tina Hartley

Created on: September 22, 2010

In general, the installation of a programmable thermostat is no different than installing a manual thermostat. With the exception of the batteries found in programmable thermostats, all thermostats have the same basic components and control the same parts of the heating and/or cooling unit.

However, there may be many differences between the number and color of existing wires. In addition, the previous installation may or may not have been done properly. A previous improper installation can lead to confusion and malfunctions from the color-coded wires being hooked up in a different configuration than expected.

To complicate matters further, thermostat wire comes in different varieties. It is not uncommon for a previous installation to have included extra wires that were not utilized. These may be twisted together, taped or left inside the wall. Checking the wire connections at the unit will indicate how many wires are actually connected.

Read the instructions included with your new thermostat to familiarize yourself with the new thermostat. Turn off the electrical supply to the unit. This is recommended when working on any electrically-powered equipment though the thermostat wiring is low voltage.

Remove the cover of the existing thermostat and make note of how the wires are connected to each terminal on the base. Remove the wires taking care they do not fall inside the wall. Marking the wires with tape can be helpful especially if they are not wired in a standard configuration. Remove the screws holding the base to the wall.

Check the new base for lining up the new mounting screws. If they don’t line up, (and they probably won’t) new holes will need drilled. If you’re working in drywall or plaster wall anchors should be used to mount the new base. If you’re lucky there is solid wood to work with even if only as a backing plate behind drywall and you’ll only need to mark for the new holes and drill pilot holes. The installation kit inside your new thermostat package may have wall anchors for use as needed.

Once the new mounting plate is installed connect the wires to the corresponding terminals. As mentioned earlier, this may or may not be a simple feat. The wire color isn’t nearly as important as making note of which wire was connected to what terminal on the old thermostat and how many wires were originally connected. There are far too many possible configurations to list here. Please do read the manufacturer’s instructions packed with your new thermostat.

Once the wires are attached, install batteries as specified by the manufacturer and attach the thermostat to the mounting plate. You’re ready to program your new energy saving thermostat according to your lifestyle preferences.

Note – please take care to properly dispose of older-style thermostats containing mercury.

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