Checklist for Meeting All Thermal Management Requirements


This checklist is intended to help design engineers verify the important thermal management requirements for enclosure cooling systems. The checklist covers environmental conditions, cooling requirements, methods of cooling, and other pertinent design aspects.

1. Establish Environmental Conditions

  • Ascertain ambient temperature range.
  • Note altitude and latitude.
  • Decide if enclosure will be an indoor or outdoor location.
  • Choose the enclosure internal temperature, taking into account thermal limits of the equipment specified by the manufacturer.
  • Clarify the relative humidity extremes and dew point to assess the risk of internal condensation.

2. Enclosure Selection

  • Determine the NEMA Rating. Should the enclosure be sealed or may it be naturally ventilated? Identify any pollutants and environmental conditions that may impact on the NEMA rating.
  • Clarify the materials of construction, insulation, and color to calculate heat convection and the effect of solar radiation.

3. Heat Load

  • Calculate the heat generated by the internal components, including relays, contactors, switchgear, variable speed drives, PLCs, power supplies, and transformers.
  • Work out the enclosure exposed surface area.
  • Determine the heat flow into, or out of, the enclosure due to the temperature differential.
  • Assess any solar radiation heat load.

4. Cooling System Capacity

  • Using an online or manual calculation method, calculate the required cooling system capacity in CFM, Watts/°C or BTU/H.

5. Select a Type of Cooling System

  • If a ventilated enclosure is preferred, does the heat load permit natural or fan assisted ventilation?
  • Alternatively, choose a closed loop cooling method such as an air to air heat exchanger or enclosure air conditioner depending on the heat load when the enclosure must be closed off from external contaminants.

6. Power Supply

  • Verify the supply voltage and frequency.

7. Identify a Need for Enclosure Environmental Protection Options

  • No special protection.
  • Dusty and dirty environments where enclosures need protection against windblown dust, dirt, as well as process-related dusts such as abrasive and corrosive dusts found in cement manufacturing.
  • Food and beverage plants where plant and equipment is subject to regular wash downs by water and corrosive chemical-based cleaners.
  • Security applications that use outdoor enclosures, accommodating heat generating telecommunication and broadband equipment and that require tamper proof enclosures.
  • Telecom – enclosures that are similar to security equipment enclosures but do not require the same degree of protection.
  • Waste water treatment plants and other environments where there are highly corrosive fluids and vapors including chlorine-based chemicals.
  • Any other special requirements that require protection of exposed components such as the condenser coil against dirt, severe corrosion, vibration, and freezing temperatures.

8. Hazardous Locations

  • For US locations, identify the hazardous area requirements in terms of NEC NFPA 70 Article 500 (Divisions) or Article 505 (Zones).
  • In other countries, refer to appropriate legislation to identify hazardous area classifications or classify in terms of the international IECEx Certification system or ATEX.
  • Establish any other statutory requirements such as the OSHA requirement for testing by a Nationally Recognized Testing Laboratory (NRTL).
  • Select a certified enclosure air conditioner or heat exchanger that meets or exceeds the appropriate hazardous area standards.

9. Condensate Removal (Enclosure Air Conditioners)

  • Is a condensate drain point required?
  • Is there equipment with condensate evaporation that avoids the need for a drain?

10. Other Requirements

  • How is the cooling system controlled and what features are required?
  • Where is the controller located and can it be relocated if required?
  • Is there compressor protection?
  • What provision has been made for alarms?
  • Is a heater required to prevent condensation at low temperatures in humid environments?
  • Does the unit switch off if the enclosure door is opened?
  • Is there provision for remote monitoring and control?
  • In the U.S., verify the enclosure air conditioner has been tested and approved by a NRTL.

Although this checklist is reasonably comprehensive, it does not allow for every possibility and users are cautioned to ensure that all other specific requirements are considered. To ensure you meet all requirements for your application, contact the experts at Thermal Edge today.