Thermostats are one little piece of technology, which has an imperative role in the day-to-day comfort of almost every North American citizen. Ever since Andrew Ure, the Scottish scientist who patented the first bi-metallic thermostat, this small temperature controller has come a long way.

In the late 19th century, around 1884, Albert Butz who invented the formed the “Butz Thermoelectric Regulator Company”, which later got merged and is now one of the iconic thermostats manufacturers in the history of thermostats, the Honeywell Inc.

With more than 180 years of hard work and a vision to provide comfortable and energy-efficient solutions to mankind, Honeywell Inc has produced umpteen number of thermostats ranging from the very basic manual ones to the high end, self learning thermostats.  

These days when digitalization and the internet of things are taking over people’s lives, there are still some of us who like the simpler version of the technology. If you are one of them, then you might like the product I am going to discuss in this article, Honeywell’s RLV3120A1005 digital non-programmable thermostat.

The house of Honeywell launched this simple yet efficient non-programmable line thermostat for electric baseboard heaters, convectors, and radiant fan ceilings, back on December 14, 2009. It is rated for 2000 watts at 240 volts and 1000 watts at 120 volts, which means it would be suitable for a 7-9 foot heater.

Honeywell RLV3120A1005 thermostat’s design

Honeywell’s RLV3120A1005 unit has a dimension of 1.5 x 6.5 x 9 inches. This rectangle-shaped thermostat weighs around 6.4 ounces and has a smooth white surface with exteriors made of strong plastic. The front panel constitutes of a digital LCD screen and two pushbuttons. The buttons are made of plastic, which may not feel great to press as these are designed to be a little tilted away from you.

What about its LCD display?

The LCD display is quite large and can be easily read by anyone. It displays the ambient temperature in either Fahrenheit format or Celsius format. You can choose either of the formats. The display temperature range of this thermostat is 0 °C to 50 °C.

Coming back to its display, one major drawback I see is that it does not have a backlight.

Below the temperature display, you will find a small flames like symbol. This indicates the heating intensity of your heater. In case the heater is not working, you won’t see this symbol. The number of flames seen can be anywhere from 1 to 5, depending on the heating intensity. A single flame symbol indicates that the heater needs to run at 20% intensity (max.) to reach the desired temperature.

This means if you see, for example, 3 flames symbol, it indicates that your heating unit may run at least (3×20)60% intensity to reach the desired temperature. This is a nice feature since it gives an idea about the heat energy being consumed.

Operation of RLV3120A1005

The operation of this non-programmable thermostat from Honeywell is really simple. Anyone can use it, as it is plain basic. This is the main reason why this product is a wise choice for you, if you are one of those who hate the high-end technologies and the complicated operation associated with them.

Just set the temperature to the desired value, and you are good to go. The thermostat will do the rest job to attain and maintain the temperature at the desired value.

How to change/ view the set temperature on the LCD screen?

As already mentioned this unit has 2 push buttons on its front panel, which serve the purpose of temperature adjustment. You can set the temperature in the range of 5 °C to 30 °C.

They are also there for another reason also. Press either of these two buttons, and you will see the set point on the LCD screen for 5 seconds. If you need to change it, you can use either the up button to increase the set point or the down button to decrease the set point.

If the temperature shown on the screen is the setpoint temperature, an arrow symbol will act as an indicator just above the temperature reading.

In case of a power outage, the thermostat retains the set temperature in its permanent memory. This saves you from resetting the temperature after every power outage.

Choosing the temperature format

As already mentioned, this unit gives you the liberty to choose from either Fahrenheit or Celsius format. You can select any of these two, whichever suits you the best.

The up and down button when pressed for 3 seconds, will display the current format. Now, using either of these buttons, you can change from Fahrenheit to Celsius or vice versa, as you need.

Will it make clicking, annoying noises during its operation?

This Honeywell thermostat is designed to work silently. Its 100% silent operation is due to the use of TRIAC switching which eliminates the unpleasant and annoying noises during its operation.

This makes it suitable to be installed at bedrooms also.

Accuracy of RLV3120A1005

This thermostat boasts a precision of ± 0.15°C / 0.27°F. This means the thermostat will throttle the heater to minimize its energy consumption. This prevents the temperature of your room to go any degree cooler or hotter than the set temperature.

The temperature is maintained at around ± 0.15°C / 0.27°F of the setpoint temperature.


As already mentioned, this thermostat can be used to control the heating devices like electric baseboard heaters, convectors, and radiant ceiling heaters. The load needs to be resistive only and can go up to 2000W at 240V and can take a minimum resistive load of 200W at 240V.

If you have a resistive load that is either rated below 0.83 A or higher than 83A, then you can not use this thermostat.

Also, this product cannot be used to control fan-forced heating system, central heating and inductive load like a system driven by a relay.


The RLV3120A1005 thermostat can be easily installed using the detailed instructions and by taking proper precautions as per its user’s guide. Both 2 wire and 4 wire installation can be carried out. The wiring of the thermostat is also as easy as connecting one of its wires to the heater wire and the other to the power supply through a solder less connecters for copper wires.

Since it is directly powered by the line power, it does not require any batteries. So there will be no worrying about the changing the batteries and the additional cost that come up with them.

Overview of the pros and cons of RLV3120A1005


  • Sturdy build and smooth plastic body
  • Simple operation
  • Two easy to use UP/DOWN push buttons
  • Large LCD display, which can be read at any angles.
  • Accurate temperature control with a precision of ± 0.15°C / 0.27°F.
  • No clicking noise
  • Compatible with electric baseboard heater, convector and radiant ceilings
  • Temperature format can be changed from Fahrenheit to Celsius and vice-versa
  • View and change the set point temperature on demand.


  • No backlight for the LCD display.
  • Plastic push buttons feels slippery to use
  • Not compatible with inductive loads

As a person who is looking for a sober non programmable thermostat, I hope this article gave you a brief about one of the plenty options available in the market.

Now that you are familiar with the features of the Honeywell RLV3120A1005 thermostat, you can decide whether it is worth your money or not.


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