Line Voltage Thermostats—a Direct Line of Control to Your Heating System

Here at Honeywell Thermostat, we can answer your questions about virtually any thermostat.  We know thermostats can be confusing, so if you don't find the answer you are looking for or are still confused give us a call.

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What is a line voltage thermostat?

A line voltage thermostat is a type of thermostat which is normally used with baseboard or radiant heating systems, such as the Honeywell TL8230A1003.  It is uncommon for a line voltage thermostat to be for cooling, although these are available (see the Honeywell T651A3018 line voltage thermostat) but a line voltage unit is only to be used for one or the other, heating or cooling.  Normally line voltage thermostats use 240 volts of power, but there are occasional older line voltage models which use 120 volts.  The voltage power is connected to the heater directly through the line voltage thermostat causing it to turn on or off through thick wires.  These thermostats have to carry the full current drawn by the heater.  Line voltage thermostats are not to be confused with low voltage thermostats or used with gas heating systems.  TRYING TO CONNECT THE WRONG THERMOSTAT CAN CAUSE FIRES AND OTHER ACCIDENTS, SO USE CAUTION AND BE SURE YOU HAVE THE CORRECT SYSTEM FOR YOUR LINE VOLTAGE THERMOSTAT.    

Double pole or single pole line voltage thermostats?

Single pole systems have two wires and cannot turn off your heating system completely.  A double pole system has four wires and can shut off your system completely.  The double pole units have the ability to be turned until a clicking noise can be heard, so you are assured power is off.  With a single pole system you can turn the heat down significantly instead of turning off the thermostat, so to speak.  While most line voltage thermostats are designed with four wires as a double pole unit, our Honeywell T498 line voltage offers the option of 2-wire or 4-wire application.    

Getting more technical with line voltage:  What is the difference between a mechanical line voltage thermostat and an electronic line voltage thermostat?

Mechanical line voltage thermostats work through bimetallic strips that bend with the rise and fall of temperature.  When the bimetallic element heats up, the current will switch off your heating system, and when the element cools down, the heating system will go off.  Clearly, this is not the most accurate method for temperature control, and this is where electric line voltage thermostats come in.  These line voltage thermostats use thermistor sensors to do basically the same thing, but with more accuracy (thermistor coming from the words thermal and resistor).  The Honeywell T4800 line voltage thermostat has a dial with accurate temperature selection as you can see.  Sensing elements within this model, like others, promise the sensing of temperatures within +/-1 degree.  Try a programmable line voltage thermostat—Honeywell T4700 for even more added benefits! 

The Honeywell TL8230A1003 is part of the Line VoltPRO series, the leading choice for line voltage thermostats.  With features such as precise readings within one degree of accuracy, soundproofing, on/off switching, and Honeywell's classic backlit display.  Honeywell has created another family of creditable thermostats, improved just for your line voltage system.  The one degree temperature setpoint offers precise, absolute control, so that your line voltage system will never be inaccurate.  With soundproofing, the common clicking noise is reduced, so that only a light, quiet switching noise is heard with your Line VoltPRO.  The on/off switch comes with the double pole Line Volt PRO line voltage thermostats, and allows you to disconnect your heating controls when you would prefer to save energy along with money.  As with other Honeywell favorites, the Line VoltPRO is above and beyond other line voltage thermostats in its large screen with backlighting.  When upgrading your line voltage thermostat, you do not have to settle for second best.  Line voltage thermostats are available with several special features, and Honeywell has them all.  Other Line VoltPRO Honeywell thermostats include the TL7230A1004, the TL7235A1003 and the Honeywell TL8230A1003.

Check out our Full Line Voltage Thermostat Selection!