RTC (Return Temperature Control)

The Burnham Commercial RTC (Return Temperature Control) 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.

Today’s demands for comfort and efficiency require greater attention to the temperature and volume of return water coming back 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:

• Low temperature systems containing snow melt and radiant flooring applications 
• Complex system integration and control 
• Outdoor reset and warm weather shutdown 
• Misunderstanding the protection value of primary/secondary heating systems
• Conversion of steam or gravity-flow systems to pumped water systems, where the pipe sizing is not sized properly. 

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.

Features

• Protection against thermal shock and flue gas condensation 
• Simple self-diagnostic test 
• Maintains safe minimum return water temperature
• Adjustable boiler pump purge 
• 24Vac floating motor actuator for 3-Way valve

Standard Equipment (Basic RTC Kit)

• RTC control 
• 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 
• Outdoor temperature sensor

RTC Kit Selection Chart
Requires the addition of a boiler circulator.  See RTC literature for recommended circulator sizing.
Pipe size varies by application.  Refer to the boiler Installation Manual for details.

Highlights

• 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