Manual thermostats like the Honeywell CT87K are the most basic kind of thermostat. This model is only compatible with central heating systems and is not adaptable to central cooling systems. The only adjustment the CT87K requires is the temperature setting. The design of the CT87K is the same as traditional round thermostats, but the CT87K does not use a mercury switch. This eliminates the need of an anticipator that would require adjustment. The CT87K is one of the simplest thermostats on the market.
Observe the front of the Honeywell CT87K thermostat. Two temperature gauges are on the round dial. The lower gauge indicates the actual temperature of the room. The upper gauge indicates the desired temperature setting.
Grasp the edges of the ribbed circular dial with your fingertips.
Turn the dial left or right until the red indicator arrow is at the temperature you desire.