What Is the T Connection on a Trane Weathertron?

Heat Pumps

• Heat pumps are a unique appliance, offering heating and cooling. In the summer, these devices actively distribute cold air into the environment, while delivering warm air during the colder months. Trane units had an add-on in previous iterations of the appliance, directly affiliated with the T connector inside the thermostat.

What is the "T" Connector?

• Examining the internals of the Weathertron thermostat reveals a brown wire that has no equivalent in newer, non-Trane thermostats. This mystery brown wire controls a device called an outdoor anticipator, which automatically sets the internal temperature of the house in relation to the outdoor temperature. Trane submits this as a feature, allowing the heat pump to function more efficiently.

Dealing With the "T" Connector

• After the old Weathertron is removed, the brown wire protruding from the wall should be snipped and taped over with conventional electrical tape. Unless the old thermostat is replaced with a "new" Weathertron, this wire's use is discontinued moving forward unless DIY modifications are made.

How Heat Pumps Work

• Heat pumps provide heating and cooling by using an outdoor condenser, tied to the heating and cooling ducts. Heat pumps transfer heat from place to place, cooling it in the summer and passing it through your furnace for heating in the winter. Although the outdoor component doesn't last as long since it runs 12 months a year, in moderate climates it tends to be more efficient and cost effective.