Submersible Oil Heater

Fitted directly inside the oil reservoir, this heater maintains a minimum operating temperature in hydraulic power units, gear oil tanks, and similar petroleum-based fluid systems before and during cold-weather operation. The element is mounted horizontally at the tank floor and remains fully submerged throughout — not for water, aqueous solutions, or corrosive fluids.

Purpose – Cold-start failure in oil-hydraulic systems

Hydraulic oil viscosity increases sharply at low temperatures. A typical ISO VG 46 hydraulic oil may be 20–30× more viscous at 0°C than at its rated 40°C operating point. Starting a pump through cold, heavy oil draws excess current, risks cavitation, overloads seals, and produces sluggish actuator response — a warm-up period that can run 20–40 minutes in an unheated workshop before the system reaches load capacity. Gear oil faces the same constraint: a cold gearbox generates excessive friction in the meshing zones before the lubricant reaches the viscosity it was specified for.

Pre-heating the oil to a defined band before startup eliminates these effects and allows immediate load cycling.

How it works in practice

The element is sealed in a stainless steel tube and installed horizontally at the tank floor. The built-in thermostat measures the element's surface temperature — not the bulk oil temperature. In a large tank this matters: bulk oil may be 5–10°C below the element surface reading when the heater first cycles off at 40°C, because heat transfer from the element to the surrounding oil mass takes time. The ≥30°C switch-on point creates a controlled thermal band that maintains oil above the cold-start threshold without sustained high-temperature exposure.

The IP68 terminal enclosure must remain above the oil surface at all times. The heater operates unsupervised — no external controller required.

Key features

• Three power levels (250W, 500W, 1000W) and three body lengths (225 / 325 / 525 mm) — match to tank volume and available immersion depth
• Available in 230V AC and 24V DC — the 24V variants suit mobile equipment, construction machinery, and DC hydraulic systems
• Fixed thermostat: 40°C cut-off, ≥30°C switch-on — maintenance-free, no settings to drift
• Stainless steel tube — compatible with petroleum-based hydraulic oils, gear oils, and cutting oils
• IP68 terminal enclosure — withstands workshop humidity and incidental oil splash

Certification & Approvals

• CE approved
• Protection rating: IP68

Technical Specifications

• Tube material: Stainless steel
• Thermostat cut-off: 40°C (fixed)
• Thermostat switch-on: ≥30°C (fixed)
• Protection class: IP68

Applications

• Hydraulic power packs in cold stores, outdoor installations, and unheated workshops
• Machine tool hydraulic systems requiring a defined minimum startup temperature
• Agricultural and construction equipment with hydraulic or gear drives
• Mobile equipment with 24V DC power supply (24V variants)
• Gear oil reservoirs in gearboxes, transmissions, and reduction units requiring winter pre-heating

Operational Requirements

• For petroleum-based fluids only — not for water, aqueous solutions, or acidic fluids
• Element must remain fully submerged at all times during operation
• Terminal box must remain above the oil surface — do not submerge
• Do not operate if oil level drops below the element — will result in irreversible element burnout