Thermo 2000 electric boilers: Mini BTH Vs Mini Ultra

Thermo 2000 electric boilers: Mini BTH Vs Mini Ultra

Nordik Radiant |

In the ever-evolving world of heating technology, homeowners and industry professionals are seeking reliable, efficient, and compact solutions to meet their heating needs. This is where Thermo 2000 Mini BTH and Mini Ultra boilers come into play, offering a combination of exceptional performance, compactness, and energy efficiency. In this article, we delve into the features and benefits of these innovative boilers.

It's Mini

In today's world, where every square centimeter matters, size should never compromise style or functionality. Mini BTH and Mini Ultra electric boilers embody the perfect alliance between compact design and refined aesthetics. The Mini BTH and Mini Ultra offer outstanding performance in a format that seamlessly integrates into any space, large or small, and in various configurations with very easy wall installation. This frees up valuable square meters in mechanical rooms that are becoming increasingly smaller.

Green Alternative

Thermo 2000 Mini electric boilers range operate without combustion, thus completely eliminating greenhouse gas emissions (GHGs) and significantly reducing the carbon footprint, making them an environmentally friendly solution. Electrical energy is directly converted into heat without energy loss, providing high energy efficiency.

Mini Ultra VS Mini BTH

Thermo 2000 Mini Ultra and Mini BTH electric boilers have some significant differences in terms of features and applications. Here's an overview of the main distinctions between these two models:

Difference between Thermo 2000 Mini BTH and Mini Ultra radiant floor electric boiler


  • Size and Weight
  • 3/4" Inlets and 3/4" Outlets
  • High-temperature limit safety control
  • Heating pump power supply
  • 30 psi safety valve
  • Drain valve
  • 208/240VAC input power (3 to 12 kW power)
  • Integrated 24V output power for thermostat and other accessories supply


The table below illustrates the differences between the Thermo 2000 Mini BTH and Mini ULTRA electric boilers:

Mini BTH


Indicator lights indicating functioning elements

Ultra-Smart TM controller allows for a quick and complete view of the device's operating status

Manual temperature set by aquastats

Preset based on heat distribution system used

Power modulation according to heating demand

Intelligent water temperature modulation with standard outdoor temperature sensor

On/Off switch

Heating shutdown when outdoor temperature is high


"Boost" mode for automatic temperature increases when required


Operates only upon thermostat demand


Possibility of pump purge upon shutdown


Easily paired with an auxiliary boiler for dual energy installation


Digital Controller (Ultra Smart)

ZEL100-ULTRA Thermo 2000 electric boiler UltraSmart replacement controller for Ultra Thermo2000 water and glycol radiant floor electric boiler

The Mini Ultra boiler is equipped with Thermo 2000's Ultra Smart controller, offering advanced features such as temperature modulation of the liquid based on outdoor temperature, resulting in a more responsive system. However, the Mini BTH features are more limited, as we'll see later in this article.

 We'll also cover the Ultra Smart controller operation in more detail later in this article.

Temperature Adjustment

The operating parameters of a hot water heating system vary depending on the type of heating system the boiler is installed on (e.g., hydronic radiant floor operates at much lower water temperatures compared to hot water baseboards).

The table below provide a good indication of the temperature that normally are required for different applications.


Hot water baseboards

Cast iron radiator

Hydronic floor (pipe installed between joists)

Hydronic floor with pipe cast in concrete

Température (°F)

160°F à 185°F

135°F à 165°C

110°F à 140°F

85°F à 115°F

Température (°C)

70°C à 85°C

57°C à 74°F

43°C à 60°C

30°C à 46°C


Temperature adjustment on Mini BTH differs from that of Mini Ultra. On Mini BTH, the temperature is adjusted as follows:

An aquastat controls each heating element which enable to set the start-up temperature. the setpoint of each aquastat is set by turning the knob. The red point under the knob serves as a reference in regards to the values written. First, using one of the knobs (whichever of the two), the highest supply temperature required by the heating system is set.

When the boiler is equipped with 2 aquastats (model range from 7.5 kW to 12 kW only), adjust the temperature of the second aquastat to about 5°F below the setpoint of the first one.

On the other hand, with Mini Ultra, the liquid setpoint temperature is adjusted directly on the ULTRASMART digital controller (which will be presented later in the article).)

Heating shutdown when outdoor temperature is high

The Mini Ultra boiler also offers the option for the boiler's setpoint temperature to be modulated using the outdoor temperature (the colder it gets, the higher the boiler's setpoint temperature will be).

This is possible by connecting the outdoor sensor provided to the terminals S1 S2of the boiler before powering up the unit. Installing the sensor also allows, in addition to modulating the liquid setpoint temperature, preventing the boiler from heating when the outdoor temperature is high (e.g., in summer), even if a thermostat on demand.

So, when spring come, the Mini Ultra boiler will automatically stop heating.

In contrast, in the case of the Mini BTH boiler, you will need to remember to turn off the switch the unit to prevent it from heating the liquid during the hot season.

The Ultrasmart Intelligent Controller

The Ultrasmart Intelligent Controller was designed exclusively for Thermo 2000 electric boilers to provide users with a unique heating experience. This controller aims to provide access to a higher level of comfort and ensure optimal performance of your heating appliance. This controller also simplifies interaction with your boiler. Its interface provides instant access to all features at your fingertips.

The controller efficiently adjusts the boiler's power and temperature according to your needs. It is important to note that the operational settings of a hot water heating system may differ depending on the type of application for which the boiler is installed.

Ultra Smart Controller Display

Thermo 2000 hydronic radiant floor electric boiler ultra smart digital controler

The controller allows you to quickly view the device's operating status. On the controller's home screen, you can view the following parameters:

  • Target temperature or boiler off indication
  • Actual boiler temperature
  • Heating Pump Running
  • Operating mode (electric or dual energy)
  • Number of elements in operation
  • Boost mode in operation
  • Boiler off when temperature is too high

As shown in the photo, the controller uses four push buttons to select and adjust parameters.

Thermo 2000 ultrasmart controler in operation
Thermo 200 Ultra Smart buttons

Here's the function of the 4 buttons:

Symbol Name Function
Plus or Minus The + and - buttons are used to select an item or adjust a value.

The key button is used to access the controller's configuration menu and to confirm a selection.

Light Bulb

By default, the backlight is automatically set for a period of 10 seconds each time a button is pressed.

By pressing the button with the light bulb symbol, the backlight will be continuous.Simply press the button again to return to the default backlight mode.

At startup, the boiler must be configured based on the type of installation.

Here's how to proceed with the main settings:

1. Hold the Key button for two seconds to access the configuration menu.

2. Select the temperature measurement unit the user prefers to operate with (°F or °C) by default °F

3. Select the type of heating system on which the boiler will be installed.

  • Embedded radiant floor in concrete
  • Radiant floor installed between joists
  • Cast iron radiators
  • Hot water baseboards

Whether it's an installation with or without an outdoor sensor, it's important to adjust the maximum target temperature to an adequate value, which will ensure proper heating of the building when the outdoor temperature is at its lowest.

4. Select the operating time of the circulating pump after a heat demand (options are ON, OFF, 15 sec. To 60 min) By default, it is programmed to 30 Sec.

If the heat distribution system is equipped with zoning electric valves (actuators?), select OFF.

5. When the outdoor sensor is installed, select the outdoor temperature value at which the building no longer requires heating (0°F to 105°F) By default, it is programmed to 75°F (24°C).

Once these settings have been established, the controller will automatically return to the home screen.

If necessary, the target temperature can be manually adjusted, this can be done without entering the configuration menu.

The setpoint temperature can be shifted by plus or minus 10 °F by pressing the Plus or Minus button. 

If the setpoint temperature value displayed is 0, this means that the original target temperature will be maintained.

Boost Mode

The Thermo 2000 boiler is also equipped with a boost mode, which automatically increases the boiler water temperature to meet prolonged heat demand.

The boost mode can be activated or deactivated by pressing and holding the Key button for 6 seconds and selecting ON and OFF with the Plus or Minus button.


Regular maintenance of the boiler will ensure trouble-free operation for years to come.

It is recommended to establish and follow a maintenance program. Any component is subject to eventual failure. The use of incorrect replacement parts or bypassing repair procedures and warnings can reduce the boiler's safety level and decrease its lifespan.

Immediate inspection should be performed in the following cases:

  • A smell of burnt plastic or overheating of materials.
  • Water leakage from the boiler or distribution system.
  • If a leak is detected at the safety valve outlet, there may be a problem with certain components installed on your heat distribution system.
  • Never block the safety valve.

At the beginning of the heating season, check the proper operation of the boiler's operation and safety controls, as well as the operation of the circulating pump and other heat distribution system components.

It should be noted that any replacement of defective components should always be carried out with genuine parts


As for the warranty of the Mini Ultra and Mini BTH boilers, it is as follows:

  • A fifteen (15) year period from the purchase date on the tank.

The warranty is valid as long as the purchaser owns the building where the installation was made. In the event of a leak due to a manufacturing or material defect occurring within the limited warranty period, and confirmed by an authorized representative, Thermo 2000 Inc. will repair or replace, at its discretion, the faulty unit with the most similar unit available at the time of replacement.

The original purchaser is responsible for all removal and reinstallation costs, transportation, and handling to and from the manufacturer. The replacement unit will be warranted for the remaining period of the original warranty.

  • A two (2) year period from the purchase date on all parts or components of the Mini Ultra and Mini BTH boilers against manufacturing or material defects.

The original purchaser is responsible for all removal and reinstallation costs, transportation, and handling to and from the manufacturer. The repaired or replaced component will be warranted for the remaining period of the original warranty.


In conclusion, Thermo 2000 Mini BTH and Mini Ultra boilers stand out as exceptional heating solutions, combining performance, compactness, and environmental friendliness. With their compact design, they optimize space while offering easy and aesthetic installation. 

If you'd like to learn more about Thermo2000 boilers, we invite you to visit our online store You'll find a complete range of heating products, including Thermo2000 boilers. Feel free to explore our selection and find the perfect solution for your heating needs.