COCOON THRMS-1-2900 Thermal Mass Duct Heater

The COCOON THRMS-1-2900 Thermal Mass Duct Heater is engineered to deliver high-capacity supplemental heating that helps stabilize indoor temperature swings while enhancing comfort in larger residential, commercial, industrial, and specialty HVAC applications.

Unlike conventional electric duct heaters that produce immediate on/off heat output, COCOON Thermal Mass Technology stores thermal energy and releases it gradually. This creates a smoother, more consistent flow of heated air, reducing rapid temperature fluctuations while improving overall HVAC system efficiency and occupant comfort.

The THRMS-1-2900 is designed for demanding applications requiring increased heating capacity, enhanced zoning support, and superior airflow balancing without the need for a complete HVAC system redesign. Ideal for larger buildings and high-load environments, it delivers dependable supplemental heating while integrating seamlessly into existing ductwork.

Key Benefits

• Helps stabilize indoor temperature swings by smoothing heat delivery in the air stream
• Provides supplemental heating support for larger or uneven HVAC zones
• Reduces hot and cold fluctuations in delivered air for more consistent comfort
• Uses Thermal Mass Technology to store and release heat more consistently than standard electric duct heaters
• Improves overall comfort by supporting existing HVAC system performance rather than replacing it
• Designed for flexible installation in vertical, horizontal, or downflow configurations
• Integrates into existing ductwork with minimal system modification
• Compatible with grid power, solar, backup generators, and hybrid energy systems
• No venting required
• Suitable for residential, commercial, and specialty HVAC applications
• Engineered and manufactured in the United States

General Specifications

THRMS-1-2900-R-P8

Energy Source: Electric Grid, Solar, Wind, Hydro, Backup Generator, or Hybrid Energy Systems

Venting Required: None

Emissions: None

BTU Capacity: 122,148 BTUs

Active BTU: 73,702.27 BTUs

Stored BTU: 48,445.73 BTUs

Active KW: 21.6

Number of Circuits: 2

Number of Circuit Breakers: 2

Voltage: 208-240V / 480V

Hertz: 50 / 60

Full Load Amps: 45 each

Maximum Overcurrent Protection: 60 Amps each

Minimum Circuit Ampacity: Per NEC and local codes

Circuit Ampacity: 58 Amps

Recommended Breaker: 60 Amps

Installation Orientation: Vertical, Horizontal, Downflow

Electrical Phase: Single Phase standard (Three Phase available, contact for availability)

Unit Dimensions: 18 x 24 x 54 in

Product Weight: 150 lbs

Shipping Weight: 170 lbs

Safety Listing: UL Listed File Number SA44706

Warranty Information

• 1-Year, 5-Year, and 10-Year Limited Warranty Options
• 10-Year Heat Exchanger Warranty
• See Warranty Documentation for Complete Details

Shipping Information

Shipping Method:
LTL Freight (Where Available)

Shipping Weight:
170 lbs

Country of Origin:
United States

Application Assistance

If you have questions regarding sizing, electrical requirements, installation configuration, or application suitability, our team is available to help determine the best COCOON solution for your project. Call us at +1 314-931-1004