How to choose an immersion heater?

How to choose an immersion heater?

1. Choose the right armor material

  The most important factor is that the material or liquid will directly contact the heating tube. In many cases, different armor materials can be used. If the specifications allow or require only stainless steel to be used, make sure which one is compatible. In most cases, stainless steel is used, which is now very popular and cheap; in the past, copper or steel was used.

2. Choose surface load

  It is recommended to choose a surface load that does not produce partial boiling of liquid on the surface of the heating tube. This phenomenon is called cavitation, which can cause rapid wear of the protective sleeve of the heating tube, liquid decomposition or chemical changes, limestone deposition and pollutants (carbonate, chloride, etc.). As for drinking water, when the water temperature reaches 65°C and the hardness of the water exceeds 10dH, these precipitation processes will increase.

3. Choose joint or flange

  Joint material: It is important to consider the material of the immersion heater joint, and its corrosion resistance must be compatible with the liquid. Most heaters use threaded brass joints, which are brazed to the heating tube. For those applications where brass cannot be used, stainless steel joints made of 304L or 316L can be used. It can be brazed with copper alloys or argon arc welding in most difficult situations.

4. The choice of shell

  In addition to a variety of moldable shapes, the plastic housing has interesting electrical insulation properties, chemical resistance and corrosion resistance. They are generally cheaper because their surface protection does not require painting. However, their lower mechanical properties or thermal resistance are often criticized. It is not the defect of the plastic itself, but the designer of these shells, usually from southern Europe, who often have the cheapest plastic and the lowest weight material at a discount, which damages the strength and does not meet the technical requirements.

5. Select temperature controller and safety device

  Traditional immersion heaters, when they are equipped with a temperature control device, use a mechanical thermostat, and the sensor is installed between a temperature probe and the heater. This is a small and reliable solution. Now it is also possible to produce compact immersion heaters with electronic temperature controllers, which can be combined with or without fail-safe manual reset safety  thermostats.