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Product Summary

This Mr. Heater Big Maxx™ Natural Gas High-Output Commercial Unit Heater is quiet and vented for easily heating a large 10,000 sq. ft. building. The low-profile design requires only 1in. clearance from the ceiling and delivers 300,000 BTU output. Easily installs using 3/8-16 threaded rods (sold separately). CSA certified. Works with Thermostat Item# 173641 (sold separately).

Features + Benefits

  • Requires only 1in. clearance from ceiling with threaded rods (sold separately)
  • Spark Ignition with self diagnostic control module
  • Designed for right or left side piping, electrical and flue connections by simply rotating 180°
  • Aluminum tubular heat exchanger for maximum efficiency and longer life
  • Ships as Natural Gas unit
  • Easy external access for thermostat connections and AC terminals
  • Compatible with WiFi/Digital thermostats (not included)
  • Power exhaust with 6in. flue allows for vertical or horizontal venting (Category 1 Vertical and Category 3 Horizontal venting, kits sold separately)
  • Max mounting height of 18ft. from floor to bottom of heater (18in. clearance from side, rear, and corner walls) * 1/2in. gas connection
  • Thermostat sold separately -- Item# 173641
  • Check local codes and ordinances for approved installation and usage -- See product manual for venting and electrical supply requirements
  • Can be converted to LP using Item# 5261120 (sold separately)
  • Physical appearance of the MHU300 may vary from what is shown, but will fit all required venting

Features + Benefits

  • Requires only 1in. clearance from ceiling with threaded rods (sold separately)
  • Spark Ignition with self diagnostic control module
  • Designed for right or left side piping, electrical and flue connections by simply rotating 180°
  • Aluminum tubular heat exchanger for maximum efficiency and longer life
  • Ships as Natural Gas unit
  • Easy external access for thermostat connections and AC terminals
  • Compatible with WiFi/Digital thermostats (not included)
  • Power exhaust with 6in. flue allows for vertical or horizontal venting (Category 1 Vertical and Category 3 Horizontal venting, kits sold separately)
  • Max mounting height of 18ft. from floor to bottom of heater (18in. clearance from side, rear, and corner walls) * 1/2in. gas connection
  • Thermostat sold separately -- Item# 173641
  • Check local codes and ordinances for approved installation and usage -- See product manual for venting and electrical supply requirements
  • Can be converted to LP using Item# 5261120 (sold separately)
  • Physical appearance of the MHU300 may vary from what is shown, but will fit all required venting

Warranty

Manufacturer's Warranty

3 year limited warranty