Outdoor HVAC Enclosures Require Temperature Maintenance

enclosure heater SLB

The Challenge
A rating/testing agency that provides third-party approvals informed an HVAC manufacturer that one of its air-cooled chiller model’s fan circuit drives were not rated for the model’s maximum low temperature, negating the required approval. While the drives were rated to 10° F, the chiller was approved to -20° F. A fast solution was required for both new unit manufacturing and field unit retrofits to raise the unit temperature to accommodate the drives – and re-establish the necessary third-party approval.

The Solution
Chromalox reviewed the situation and came up with not one, but two, potential solutions. The first was to add an enclosure heater to the unit’s cabinet to heat the enclosure to 30° F above ambient temperature. The solution includes controls to save energy during warmer weather. The second option involved applying heat directly to the unit’s inverter, eliminating the need to heat the entire cabinet. The customer opted for the second option, which saved both energy and expense. A pressure-sensitive adhesive secures the heater directly to the side of the inverter. Heaters are remotely controlled through small, inexpensive snap disc thermostat.


  • Two solutions offer options to meet third-party requirements
  • On-site engineering support provided fast turnaround to gain necessary third party approval
  • Economic, energy-saving solution