Products / Hydronic Heating / Unit Heaters

Rittling Unit Heaters

Rittling Unit Heaters provide uniform heating you can count on in large open areas. Our high efficiency units offer low installed costs and provide large heating loads without the need for extensive ductwork systems.


Zehnder Rittling has refined the Unit Heater design, resulting in an energy-efficient, highly effective product. A combination of smaller units and higher CFM models are available to fill the need for a variety of mounting locations for optimal heat distribution. You won’t find any other heating system that creates a comfortable, healthy and energy-efficient indoor climate like Zehners Unit Heaters.




Air distribution is virtually unlimited with Rittling Unit Heaters. All steam/hot water unit heaters are available in a wide range of models and airflow arrangements to satisfy the demands of your specifications and provide years of reliable operation and energy-efficient comfort.

  • Heavy duty construction with epoxy powder coat finish for extended operating life cycle
  • Easy electrical connection
  • Factory tested components to ensure proper function when unit arrives on site
  • Totally enclosed motors with thermal overload protection
  • Optional air diffusion accessories can be provided to offer a wide variation in air distribution patterns
  • Low installed costs





Rittling Unit Heaters offer the latest in attractive design and are engineered to provide years of reliable operation and energy-efficient comfort.

  • Horizontal models have squared off, picture frame style fronts for a clean, defined appearance
  • Louvers on horizontal units are rounded off and are aesthetically pleasing
  • Vertical models are attractive and formed of 16-gauge cold rolled steel
  • All Unit Heaters are treated for corrosion-resistance and finished with a durable epoxy-based gray textured powder coating
  • All Unit Heaters offer smooth and consistent airflow
  • All Unit Heater motors are totally enclosed
  • Air distribution is virtually unlimited
  • All motor horse-power and fan configuration chosen for quiet operation and efficient air output
  • All motors supplied with low speed tapping, usable when noise is a concern. Optionally, a variable speed controller can be added for infinite variability.



Rittling Unit Heaters provide uniform heating in large open areas. These units offer a low installed cost while providing large heating loads without the need for extensive ductwork systems. When selecting the quantity, style, size and placement of Unit Heaters, it is important to determine the heat loss in accordance with ASHRAE guidelines. The building’s construction, number of occupants, type of machinery and daily activities need to be considered in the overall design. Airflow should be directed to the areas of greatest heat loss using horizontal and vertical louvers for complete directional control. Mount units as low as practically possible. Higher CFM units should be employed for higher mounting locations to ensure that the heat reaches the occupied area. Better heat distribution can be achieved through the use of additional smaller units.


  • Schools
  • Offices
  • Libraries
  • Hospitals
  • Foyers
  • Restrooms
  • Showrooms
  • Department stores
  • Clubhouses
  • Commercial dining facilities
  • Large lobbies
  • Warehouses
  • Stores
  • Gymnasiums
  • Bars
  • Factories
  • Shipping areas
  • Machine shops
  • Stadium common areas
  • Fabrication shops 

Unit Heaters