How over-the-side immersion heaters work and their construction
An over-the-side immersion heater is a tubular electric heating element designed to be suspended into an open vessel from above the rim — without requiring any permanent modification to the tank or container.
The heater consists of a stainless steel tubular element (AISI 316L) bent into a U or L configuration, connected to a terminal box with an integrated thermostat. The element is lowered into the liquid and held in place by hooking over the tank wall, making it immediately deployable in any accessible open vessel.
Heat is transferred directly from the element surface to the surrounding liquid through convection. With a surface power density of approximately 2.5 W/cm², the heater raises liquid temperature efficiently — faster than low-density alternatives — while the thermostat maintains the target temperature within the set range.
The IP67-rated terminal box protects internal connections against moisture and splashing, making the unit suitable for wet industrial environments without additional enclosure.
Key advantages of over-the-side immersion heaters
Over-the-side immersion heaters are widely used in industry because they combine direct liquid heating with rapid, tool-free installation — a combination that fixed heating systems cannot offer.
The most important advantages include:
- No tank modification required — installation over the rim takes seconds
- Integrated thermostat with adjustable range (30–90°C) for automatic temperature control
- Acid-proof AISI 316L stainless steel construction for compatibility with water-based and industrial liquids
- IP67-rated terminal box for reliable operation in wet and humid environments
- Portable and redeployable across multiple tanks or locations
- CE certified (LVD, EMC, RoHS) for safe use across industrial and commercial applications
These properties make over-the-side immersion heaters a practical solution wherever temporary, flexible, or supplementary liquid heating is required.
Typical applications of over-the-side immersion heaters
Over-the-side immersion heaters are used wherever liquids in open vessels need to be heated, maintained at temperature, or protected from freezing — without permanent installation:
- Heating water and process liquids in open tanks, barrels, and industrial containers
- Frost protection in exposed or unheated storage areas during cold periods
- Workshop and maintenance heating of liquids for cleaning, surface treatment, or preparation processes
- Temporary heating during plant maintenance, seasonal operations, or equipment changeovers
- Supplementary heating in facilities where permanent tank heating is unavailable or impractical
The over-the-side format is particularly well suited to operations where the same heater must serve multiple tanks, or where heating requirements change between production runs or seasons.
Because no welding, drilling, or tank modification is involved, over-the-side immersion heaters can be installed and removed by maintenance personnel without specialist tools or downtime.
Frequently asked questions:
An over-the-side immersion heater is a portable electric heating element designed to be suspended into an open tank or container from above the rim. It heats the liquid directly through immersion, requires no tank modification, and is typically fitted with an integrated thermostat for automatic temperature control.
Over-the-side immersion heaters in AISI 316L stainless steel are compatible with water, water-based solutions, and many industrial liquids. The material selection should always be matched to the specific liquid being heated — for aggressive chemicals or special fluids, element material and watt density must be specified accordingly.
The integrated thermostat is adjustable between 30°C and 90°C, covering the most common temperature requirements for industrial liquid heating, frost protection, and process preparation. The thermostat automatically cycles the heater on and off to maintain the set temperature.
Yes. The terminal box is rated IP67, meaning it is protected against dust ingress and temporary submersion. This makes the heater suitable for use in wet industrial environments, near splashing liquids, and in areas subject to wash-down procedures.
Yes. With the thermostat set to a low temperature, over-the-side immersion heaters are an effective and low-cost solution for preventing freezing in open tanks and containers exposed to cold conditions. The automatic thermostat ensures the heater only operates when required, keeping energy consumption low.
Explore over-the-side immersion heaters for open tanks
Kuhlmann Electro-Heat supplies over-the-side immersion heaters for industrial and commercial liquid heating applications. Our standard range is manufactured in acid-proof AISI 316L stainless steel with integrated thermostat control and IP67 terminal protection.
Whether you need a single unit for maintenance use or a quantity for production, our immersion heaters are stocked and available for immediate delivery.
Need an immersion heater specified for your tank or process?
Standard over-the-side immersion heaters cover most open-tank applications, but some processes require specific element lengths, higher power outputs, alternative materials, or custom thermostat ranges.
Our engineering team can specify and supply immersion heaters designed for your exact liquid, vessel geometry, and temperature requirements — from single units to volume orders.
Contact us to discuss your application and we will recommend the right solution.