RTC (Return Temperature Control)

The Burnham Commercial Return Temperature Control (RTC) provides an economical and effective means of boiler protection from thermal shock and sustained condensing operation. The RTC monitors the boiler return water temperature and operates a 3-way diverting valve and boiler circulator to maintain a minimum return temperature of 135ºF or greater.

By incorporating a motorized 3-way valve into the “boiler envelope,” the RTC is able to temper the water coming back to the boiler. If the return water temperature drops too low, the RTC will divert hot supply water away from the system loop and back into the return piping, raising the temperature to a safe level. The RTC is available with an optional outdoor reset kit, which will vary the system temperature based on outdoor reset. On the coldest winter days, the RTC will raise the system temperature in order to match the load demand. On mild spring and autumn days, the RTC will reduce the temperature of the system water, which can lead to more efficient operation.

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  • Protection Against Thermal Shock and Flue Gas Condensation
  • Simple Self-Diagnostic Test
  • Maintains Safe Minimum Return Water Temperature
  • Adjustable Boiler Pump Purge
  • 24 Vac Floating Motor Actuator for 3-Way Valve Standard Equipment
    (Basic RTC Kit)
  • 3″ x 12” Nipple with Tapping
  • 3-Way Valve
  • Junction Box
  • Mounting Bracket
  • Standard Equipment (RTC Kit with Outdoor Reset
  • Same Equipment as in the Basic RTC Kit
  • Universal Sensor for Mixing


  • Available on Water Boilers
  • Monitors Return Water Temperature
  • Operates a Circulator and 3-Way Valve
  • Maintains Minimum 135ºF Return Water Temperature
  • Optional Outdoor Reset Available

Why Boiler Protection?

Today’s demands for comfort and efficiency require greater attention to the temperature and volume of return water to the boiler. Many premature boiler failures can be traced to these two uncontrolled variables. Operating below minimum temperatures and flow rates creates thermal shock conditions and flue gas condensation issues, each of which can shorten the life expectancy of a boiler. Other factors that affect return temperature and flow include:

  • snow melt and radiant flooring applications
  • complex system integration and control
  • outdoor reset and warm weather shutdown
  • misunderstanding the protection value of primary/secondary systems
  • conversion of steam or gravity flow systems to pumped water systems, while retaining the original oversized distribution systems

The concept of boiler protection has existed for many years. However, the primary focus in hydronic systems is often the demand and delivery design characteristics. Frequently, little attention is given to the heat source – the boiler.


Controlling Return Temperatures

The Burnham Commercial RTC Return Temperature Control provides an economical and effective means of boiler protection from thermal shock and sustained condensing operation. By expanding the “boiler envelope” to incorporate a 3-way valve and flow control system, the RTC Return Temperature Control maintains a minimum return water temperature of 135°F or greater.

The RTC system is supplied as a kit and can be incorporated into most hydronic hot water applications with minimal modifications to the system design and operation. It provides a simple means for boiler protection and an opportunity to increase operational efficiency


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