Thermostats

by Nick Gromicko and Rob London  

Thermostats are devices designed to control the heating and cooling systems in a building so that air temperature remains comfortable. According to InterNACHI's Standards of Practice, inspectors are not required to verify, inspect or determine thermostat calibration, heat anticipation, automatic setbacks, timers, programs or clocks. It is wise, however, for inspectors to understand thermostat operation and solutions to common defects.

Thermostats can be manually controlled or set to activate automatically based on timers or room temperature readings. Most thermostats contain two meters:  the "set" temperature that the thermostat is asking for, and the actual temperature. On a traditional dial-type thermostat, the user can increase the set temperature by rotating the dial clockwise, and lower it by rotating it counter-clockwise. Newer thermostats usually have digital displays, which can be used to adjust automated  heating and cooling schedules.

Thermostat Location

In order to avoid false or "ghost" readings, which will cause unnecessary furnace or air-conditioner cycling, the thermostat must be installed so that it correctly reads the room temperature. The following locations may cause the thermostat to give false readings:

• near a heat source, such as a fireplace, hot water pipes, bright lights, direct sunlight, electrical appliances that produce heat; 
• in a drafty hallway, or near a window or exterior door that is opened often; and
• on an outside wall. Outside walls are too affected by outside temperatures, which may make the thermostat "think" the air in the house is warmer or cooler than it really is.  Read entire article...