Differences in Class I and Class II Electric Heaters

If you are replacing your inefficient storage heaters or looking at non-gas options, then you should take a look at the differences between Class I and Class II electric heaters not only for your comfort and your energy costs but your family safety, too.

Here we explain the differences between Class I and Class II electric heaters or electric radiators under current regulations and legislation in the UK.

Insulation and PAT Testing.

Class I Appliances protect the user with one layer of basic insulation and by providing an earth connection. PAT testing needs to be for insulation and for earth connection.

Class II Appliances protect the user with a minimum of two layers of insulation, built in to protect the live parts. They usually state DOUBLE INSULATED on their box or literature. Because of this, they do NOT require an earth connection. PAT Testing Class 2 appliances is only for insulation resistance. Detailed information on this link: https://www.intersafe.co.uk/news/What-does-Class-I-and-Class-II-mean-when-it-comes-to-PAT-Testing/

Radiant or Convection differences.

First make sure you find out which form of heating is used. Class I heaters use poor Convection heating, which draws the cold air up through the radiator, warms it up, and pushes it out again in an upwards direction through the top vents. This warmed air then heats the room by moving in a circular direction, falling to the floor level as it cools, and starting the process all over again. The heater itself is an empty box with a single heat element that the cold air must pass through to be warmed. Radiant and convection heat in the Class II. IntelliHeat radiators is a completely different process, with the panels of each radiator heating up and pushing out heat directly across the room – rather like the sun’s rays on a warm day.

Our Sense range electric radiators contain thermodynamic fluid that heats up 35% faster than ordinary mineral oil. In combination with a die cast aluminium body, the radiator heats up the entire (100%) surface with no cold spots. This means that every inch of its surface is the same temperature, so air entering the base of each radiator will heat up much quicker, much warmer, and will stay warmer for a longer time than Class I electric Heaters. A good example is any electric shower unit which uses the same principal, slowing down the water flow when more heat is required.

Electric Radiators Direct Heat Transfer

With the more powerful showers that use a larger heat source area, the water flow rate is much less affected. The efficiency of electric heaters using Radiant heat, depends entirely on the size of what is known as the ‘Hotspot’. Looking at a thermal image of Class I radiators, you will see a red line where the element is located. This is its ‘Hotspot’. Below this line, the heat colour then fades quickly. Below the same image taken of a Class II IntelliHeat radiator will show the entire surface area of the radiator as a red ‘Hotspot’. The difference this makes to the radiant heat levels between a Class I and a Class II radiator is substantial and can only be seen using thermal imaging cameras.

Thermal Images of RADIATORS Class 2


Guide for Class II DOUBLE INSULATED elements for electric radiators

Zoppas element for Intelli heat electric radiators provide different types of heating cartridges according to the type of application, standard low density cartridge heating elements are build in a wide range of diameters,  with maximum specific load of 6 W/cm2.

Double Insulated cartridge heating elements are make up from a stainless steel tube containing a nickel-chrome resistive spiral inserted into a ceramic insulating nucleus.

Working temperature and specific wattage load involved:

  • With low, medium and high density and nickel-chrome resistive wire.
  • PTC (positive temperature coefficient) with ceramic semiconductor.

Cartridge heating elements are CSA and UL approved with the following limits:

  • Maximum temperature: 850°C
  • Maximum voltage: 600 V
  • Maximum surface load: 35 W/cm2

Zoppas Industries Heating Element Technologies Certifications

QUALITY: Certificate IATF 16949

ENERGY: Certificate ISO 50001

Certificate validation SGSL (UNI – INAIL)

QUALITY: Certificate EN 15085-2

QUALITY: Certificate ISO 3834-3

QUALITY: Certificate ISO 9001:2015

QUALITY: Certificate EN 9100_2018 LR 10113137

ENVIRONMENT: Certificate ISO 14001:2015



T2=0.75 T1

2500 CYCLES @ 400V



zoppas electric element Class 2 for radiators
Intelli Heat electric element Class 2 for radiators

Vastly superior electronics.

There are numerous other features that distinguish a Class I from a Class II electric radiator which from first glance appear the same, BUT when you read the detailed specification, will show huge superiorities in the Class II electronics systems.

For example, the Thermostat: The IntelliHeat iSense electric heater has two electronic temperature thermostats in different positions on the heater, to provide a heat accuracy of one tenth of a degree. The Class I heaters have only one thermostat which works in 1-degree increments. Class Ielectric Heaters can therefore only react to a temperature change of 2 or 3 degrees, which in today’s engineering terms, is a very poor responsiveness. The Class II IntelliHeat radiators will react to one tenth of a degree, making them ten times more responsive and giving the end user a more comfortable and more efficient heat. They draw much less power to heat up 0.1 degree than the basic Class I heaters needing to heat up +2 or 3 degrees during its use. (1 degree = £70/year extra on your bill) Another feature of a Class II heater is the Occupancy Detection System. This provides an automatic energy saving device that will happen in every room from every radiator, with no need to visit each room and press buttons ever again.

The IntelliHeat Class II radiator constantly scans the room, using a unique lens developed specifically for the iSense. If it detects no occupancy or movement after twenty minutes, it automatically reduces the temperature by half a degree. This process repeats every twenty minutes, slowly lowering the temperature in every unused room, but if the sensor detects the movement of someone returning, it returns immediately to the set temperature. Because of the high responsiveness of the system this temperature change is achieved in minutes. Under test conditions, this feature created energy savings of 13 %. The advantage of having a cloud-based dashboard, is that each radiator will also provide this information direct to your dashboard. Moreover, should the system develop an issue, a remote access from our technicians, can check, diagnose and fix most of the issues without an on site visit. All performed through our cloud.

This enhanced energy saving process of our Class II radiators can also assess if any further energy savings can be made. For example, if you programme every radiator to be 20.5 degrees at 7am every morning and the occupancy detector knows that no one is ever there until 7.15am, it will suggest that you change the settings to suit. If you agree, you simply accept the suggestion online and the system will make the change automatically to every radiator in your home or office that applies, saving you hundreds of pounds when taken over a full year. “Smart Electric Heaters ready for the Internet Of Things” Fully compliant with ‘Lot 20’ Ecodesign Directive. double-insulated-class-2 HEATERS.

If you decide to make use of the Mysense cloud-based App dashboard, each smart radiator will also provide this information direct to your cloud-based Free APP dashboard.

“Smart Electric Heaters ready for the Internet Of Things”
Fully compliant with ‘Lot 20’ Ecodesign Directive.

Please always ask your supplier of Electric radiators for the Certification, and Energy Performance Labels.

CALI SENSE INT150D_Rating-Label_200220_B
CALI SENSE INT150D_Rating-Label_200220_B