What Are ExProof Frost Thermostats?

ExProof Frost Thermostats are protected control devices that detect low-temperature risks on coil surfaces or in air ducts in HVAC systems and initiate a safety scenario before freezing occurs.

In ATEX-zoned areas where standard frost thermostats are unsuitable from a safety perspective, models with ExProof housings and connection structures designed for explosive atmospheres should be selected.

Operating Principle

Frost thermostats monitor temperature decreases through a sensing element installed along the coil surface or air duct. The contact output changes when the temperature falls below the defined safety limit.

This contact output can be used to stop the fan, close the fresh-air damper, open the hot-water valve, activate an alarm or switch the automation system to protection mode.

Applications

• ATEX-zoned air handling units
• ExProof fresh-air units
• Heating and cooling coils
• HVAC systems with hot-water and glycol coils
• Chemical and petrochemical plants
• Areas containing paint, solvents and flammable vapours
• Battery rooms and areas with hydrogen risks
• Process ventilation systems
• Industrial exhaust and fresh-air ducts
• PLC, BMS and automation panel integrations

Technical Features

• ExProof housing and safe connection structure
• Model options suitable for ATEX areas
• Low-temperature detection and contact output
• Wide-surface monitoring with a capillary or sensing element
• Adjustable or fixed setpoint options
• Contact structure suitable for fan, damper, valve and alarm control
• Panel, field or device-mounted installation options
• Field use compatible with the required IP protection class
• Integration with PLC, BMS and mechanical automation systems

System Advantages

• Helps detect coil-freezing risks early.
• Provides safe temperature control in areas with explosive-atmosphere risks.
• Can operate with fan, damper and valve control scenarios.
• Reduces the risk of coil damage, water leakage and process downtime.
• Supports safe shutdown and protection scenarios for HVAC systems.
• Provides alarm and monitoring capabilities through automation systems.
• Contributes to equipment safety and operational continuity in industrial plants.

ExProof Frost Thermostat Selection Criteria

When selecting ExProof Frost Thermostats, not only the temperature setpoint but also the coil type, duct dimensions, sensing length, zone classification, contact structure, automation scenario and ambient conditions should be assessed together.

• Coil type and system structure to be protected
• Air-duct or coil-surface dimensions
• Capillary length and sensing point
• Low-temperature alarm setpoint
• ATEX zone classification and certification requirement
• Contact type and electrical connection requirement
• Fan, damper and valve control scenario
• PLC, BMS or mechanical automation integration
• Maintenance access and field-installation suitability

Coil Freeze Protection

In cold climates, hot-water coils in fresh-air units may face freezing risks because of low air temperatures. A frost thermostat helps prevent coil damage by detecting this risk early.

When a low temperature is detected, the system can close the fresh-air damper, stop the fan, open the hot-water valve and send an alarm to the maintenance team.

Use in ATEX Areas

Frost thermostats used in areas with explosive-atmosphere risks must have an ExProof protection structure. Because standard devices can create electrical risks in these areas, products appropriate to the zone classification must be selected.

HVAC safety scenarios in areas with risks from chemical vapours, solvents, hydrogen, paint, gas or dust should be designed with equipment that meets ATEX requirements.

Automation Integration

Contact information from frost thermostats can be transmitted to a PLC, BMS, SCADA, fan control panel, valve control system or alarm panel.

This integration makes it possible to implement fan shutdown, damper closing, hot-water valve opening, pump start-up or system-alarm scenarios in low-temperature conditions.

Maintenance and Commissioning

For safe operation of ExProof frost thermostats, the sensing-element placement, cable connection, contact output, setpoint and automation scenario must be checked correctly.

During commissioning, fan shutdown, damper closing, valve opening, alarm generation and automation-screen monitoring functions should be tested.

Airtes ExProof Freeze Protection Solutions

For ExProof Frost Thermostats used in ATEX-zoned facilities, Airtes supports the correct product selection by assessing the coil type, ambient conditions, zone classification, automation infrastructure and protection scenario together.

With a project-specific approach, safe freeze-protection solutions can be created for ExProof HVAC, fresh-air, exhaust and process-ventilation systems, fan-damper-valve control and emergency scenarios.

Why Airtes?

• Technical experience in ATEX-area and ExProof equipment applications
• Correct product selection for coil, duct and HVAC system structures
• Technical support for fan, damper, valve and alarm scenarios
• Solution approach suitable for PLC, BMS and control-panel integration
• Project-based assessment for freeze protection, safe shutdown and equipment-protection scenarios
• Professional support in site surveys, technical analysis and quotation processes

Frequently Asked Questions

What do ExProof Frost Thermostats do?

ExProof Frost Thermostats detect low-temperature risks in coils and duct systems in ATEX areas and generate an alarm or control signal before freezing occurs.

Can a standard frost thermostat be used in an ATEX area?

Using a standard frost thermostat is not suitable in areas with explosive-atmosphere risks. An ExProof product appropriate to the zone classification should be selected.

Which equipment can a frost thermostat control?

It can operate in integration with fans, fresh-air dampers, hot-water valves, pumps, alarm panels, PLCs or building automation systems.

How should the product be selected?

The coil type, duct dimensions, capillary length, setpoint, zone classification, contact output and automation scenario should be evaluated together.

Contact Airtes for ExProof Frost Thermostats Suitable for Your Project

ExProof Frost Thermostats should not be selected before analysing the coil type, duct structure, ambient temperature, zone classification, contact requirement, fan-damper-valve scenario and automation infrastructure in your facility. The Airtes technical team provides professional support for a freeze-protection solution suitable for your operation.

You can contact us for detailed information, a site survey and a project-specific quotation.