Common Thermostat Problems
Most thermostat failures are not disasters.. Chances are, no shooting sparks, puffs of smoke or piercing alarms will signal you have a problem. It may be obvious, like the furnace refuses to come on or the display isn’t lit, or you may notice that the house is cooler than the temperature setting. All you know is something’s wrong and you want it fixed. Always start with the thermometer, troubleshooting according to the symptom. Many symptoms and causes overlap, and the general solutions narrow down to one of a handful of fixes.
Furnace or Central Air Doesn’t Start
Check for power. A blown fuse, tripped circuit breaker or dead batteries will prevent the thermostat from turning on the appliance.
Is the thermostat excessively dirty? Buildup of dust, dirt, spiderwebs and nicotine, for example, can coat the inside of the thermostat, interfering with both electrical and mechanical components. It’s easy to overlook the inside of your thermostat during spring-cleaning, so a dirty thermostat is nothing uncommon. Simply use a soft, clean brush – an artist’s paintbrush works well – to brush the interior components gently. Move parts to ensure you reach every portion of the thermostat. A can of compressed air, such as is used for electronics, also works well.
Are there loose wires or terminal screws inside the thermostat? Are the wires corroded? Never remove the thermostat cover without removing the batteries or cutting the power at the fuse or breaker box. Tighten screws and secure loose wires when necessary. Consult the manufacturer’s wiring schematics or have a qualified technician rewire the thermostat if needed.
Replace the thermostat if other troubleshooting methods fail.
The most expensive programmable electronic thermostat costs a couple hundred dollars, and inexpensive mechanical ones cost around $20. Worrying over a thermostat you can’t make work – or paying a professional more than a new one costs – just isn’t worth it.
Room Temperature Doesn’t Match the Thermostat Setting
Is the inside of the thermostat clean? A dirty thermostat is an inaccurate thermostat. Is the thermostat level? Hold a level underneath or above it and check. Careless installation or a forceful bump, knocking it off level, may alter the accuracy of the components.
Is the thermostat in a poorly chosen area of the home? Thermostats located in direct sunlight, in front of cold or drafty windows and doors, or isolated from the main living areas may not regulate the temperature correctly. Consider relocating the thermostat, if possible, or taking other measures to solve the problem. Consult your Sparta heating professional for further information.
The anticipator may not be set correctly. The anticipator is a little metal tab inside mechanical thermostats, mounted to a round dial with a printed scale. Pushing lightly on the anticipator, in either direction, may solve the issue. More complex adjustments require moving the anticipator to indicate the ampere setting needed for the furnace involved. Typically, this is specified in the owner’s manual or on the unit’s service panel.