The furnace cycles on and off rapidly (every few minutes) without fully heating the home.

Safety: Turn off power to the thermostat circuit before rewiring.

Steps:

• Ensure the thermostat is not located above a supply register, near a lamp, or in direct sunlight.
• On older mechanical thermostats, adjust the heat anticipator per the furnace control current rating (see the Tappan manual). Move the setting slightly higher to lengthen cycles.
• Consider upgrading to a modern digital thermostat compatible with gas furnaces.
• If cycles remain very short, have a technician check furnace sizing and limit operation.