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Thermostats
Modern thermostats for heating or air conditioning systems rarely break down. The only maintenance required is an occasional light cleaning. Don’t attempt to repair a defective thermostat; instead, replace the entire unit with a new one. Be sure the replacement is the correct voltage and type for your system.
How Thermostats Work
Thermostats are switches that are turned on by a temperature-sensitive device that, in turn, activates the switch controlling the operation of a boiler, furnace, electric heater, air conditioner, or other heating or cooling device. Low-voltage and milivolt thermostats are the most common types. The three principal parts of a thermostat are:
• Heat Sensor – usually bi-metal coil, the heat sensor contracts as it cools, tripping the switch to “on” and expands as it warms, tripping the switch to “off”.
• Switch – the switch may have open contacts (in older models) or a mercury-type contact enclosed in an airtight glass tube.
• Heat anticipator (found in low-voltage types only). The anticipator prevents the living area from overheating by shutting off the boiler or furnace just before the desired temperature is reached.
Installing a Thermostat
• After removing the old thermostat, feed the wires through the hole in the new base plate and insert the screws.
• Level the plate, and then tighten the screws.
• Strip the ends of the wires if needed, or scrape them clean.
• Wrap the ends clockwise around the terminal screws and tighten the screws.
• Mount the thermostat on the base plate.
• Using a pencil, set the anticipator pointer to match the current value marked on the gas valve.
Modern thermostats for heating or air conditioning systems rarely break down. The only maintenance required is an occasional light cleaning. Don’t attempt to repair a defective thermostat; instead, replace the entire unit with a new one. Be sure the replacement is the correct voltage and type for your system.
How Thermostats Work
Thermostats are switches that are turned on by a temperature-sensitive device that, in turn, activates the switch controlling the operation of a boiler, furnace, electric heater, air conditioner, or other heating or cooling device. Low-voltage and milivolt thermostats are the most common types. The three principal parts of a thermostat are:
• Heat Sensor – usually bi-metal coil, the heat sensor contracts as it cools, tripping the switch to “on” and expands as it warms, tripping the switch to “off”.
• Switch – the switch may have open contacts (in older models) or a mercury-type contact enclosed in an airtight glass tube.
• Heat anticipator (found in low-voltage types only). The anticipator prevents the living area from overheating by shutting off the boiler or furnace just before the desired temperature is reached.
Installing a Thermostat
• After removing the old thermostat, feed the wires through the hole in the new base plate and insert the screws.
• Level the plate, and then tighten the screws.
• Strip the ends of the wires if needed, or scrape them clean.
• Wrap the ends clockwise around the terminal screws and tighten the screws.
• Mount the thermostat on the base plate.
• Using a pencil, set the anticipator pointer to match the current value marked on the gas valve.