How to Replace a Honeywell T-87 Thermostat
The thermostat is the brain of your HVAC unit. A programmable thermostat is useful if there are usual periods of time that nobody is home or if a different temperature setting is preferred at night. There are dual stage thermostats for units that have more than one heat source, such as a heat pump with auxiliary heat elements, but for a basic heating and cooling unit, the Honeywell T-87 is a single stage, mercury free and relatively trouble free thermostat. Does this Spark an idea?
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Instructions
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1
Turn off the power to the unit, and pull the cover of the old thermostat off.
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2
Remove the screws holding the thermostat to the sub-base with a screwdriver, and remove the thermostat.
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3
Check the wires on the sub-base with a voltmeter to make sure the right breaker was turned off. Many times breakers are marked incorrectly.
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4
Remove the wires with a screwdriver. The wires should be color coded. Red is the power wire and is connected to the R terminal. Green is the fan wire and is connected to the G terminal. Yellow is the cooling wire and is connected to the Y terminal. White is the heat wire and is connected to the W terminal. If the colors of the wire are not as described, mark them with masking tape according to which terminal they are connected to.
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5
Remove the sub-base with a screwdriver. Secure the wires so they don't fall into the wall. While the thermostat is removed, it's a good time to determine if it is in the proper location. The thermostat should be about five feet above the floor, and should be relatively close to the return air vent, so as to get a good average temperature of the whole house.
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6
Install the new sub-base. If wall anchors were not used on the previous installation, they should be added now to insure a secure mounting. Push or tap the anchors in the previous screw holes, then place the sub-base and screw it in with a screwdriver.
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7
Replace the wires as they were taken off. Mount the thermostat on the sub-base. Put the cover on. Turn the power back on and test the unit.
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Tips & Warnings
Under the cover of the thermostat, there is a dial with a sliding pointer on it. This is the heat anticipator. It controls the cycle time of the unit. Normally the factory setting is sufficient, but if the unit seems to cycle too long or doesn't run long enough, the heat anticipator can be adjusted for longer or shorter cycles by adjusting the pointer.
