Thermostat Malfunctions

Problem: Thermostat is not working properly because of dirt or corrosion.

Background: A common problem causing poor thermostat operation is dust and dirt accumulation on the unit’s sensing element or contact points. A layer of dust can affect the speed with which the thermostat senses a change in temperature. This may allow the home to become too cold before the thermostat instructs the heating system to come on, or it may allow the home to become too warm before turning off the system.

What to do: Older thermostats, particularly those operating forced-air systems that move large volumes of air, should be cleaned regularly. To clean, remove the cover and use a soft brush to dust the components or use a vacuum near the unit, being careful not to damage sensitive parts. If the dirt is caked on, you may need to call a service technician. Some older thermostats may operate with contact points instead of a mercury-filled glass bulb. The two metal strips are installed parallel to each other, and make or break the electrical circuit to the heating unit. With power off, gently blow out the dust or wipe these strips with a soft cloth.

Special advice: If the contact points are corroded, they can be cleaned by pulling a piece of crocus cloth or bond paper (such as a business card) through the points. If this doesn’t do the trick, consider replacing it with a new unit or calling a service technician.

Helpful hint: Whenever thermostat wires must be disconnected from the unit, make sure they do not fall back into the opening in the wall. A good way to make sure this doesn’t hap pen is to wrap the end of the wire around the center of a pencil.




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