Faulty thermostats waste money
When should I replace my thermostat and do those programmable ones really save money?
There are two basic types of thermostats designed to work with different heating systems. Forced-air furnaces, including heat pumps, use a low voltage thermostat. These offer degree settings to control a home’s inside temperature.
Electric resistance systems such as baseboard heat, wall heaters or ceiling cable heat are typically controlled by a line voltage thermostat. These usually do not offer degree settings, making them less accurate in controlling a room’s temperature. Temperature swings can range from 3 degrees to 5 degrees. Because the electric current drawn by the heater passes directly through these thermostats, over time their contacts weld shut, causing them to stick “on,” lose calibration and wear out.
“Age more than anything will cause a line voltage thermostat to fail,” said Todd Hanson of Todd’s Heating and Cooling in Battle Ground. “On the other hand, low voltage thermostats are very dependable and are one of the last things to fail in a heating system.”
Hanson cited the example of an old line voltage thermostat that had frozen “on” and the only way the homeowner could turn off the heat was at the circuit breaker. It’s definitely time for a new thermostat if that occurs.
It’s a good idea to replace line voltage thermostats about every 10 years. You might consider replacing them with a programmable unit, which are now available from several manufacturers.
Programmable thermostats on forced-air systems definitely save energy. They allow you to set your home’s temperature to match your lifestyle, such as when you are sleeping or away. You no longer need to remember to turn down the heat when you leave home.
We estimate customers can save between 1 percent and 2 percent on the heating part of their energy bill for each degree they lower the temperature for an eight-hour period. That savings can add up during a heating season.
Programmable thermostats are especially valuable for use with heat pumps. In fact, we require them for customers using our heat pump loan program because they allow the system to operate more efficiently. That’s because a programmable thermostat will gradually increase the heat using the heat pump rather than the auxiliary heat coming from the furnace.
It is important to install the correct type of thermostat with your heating system and wire it correctly. Hanson said he has seen cases where a homeowner installed a line voltage thermostat on a heat pump and it wasn’t shutting the system off.
