Series GM/Flex-Heat®

Products » Multiple/Modular Systems » Series GM/Flex-Heat®

The Peerless® Flex-Heat® Hydronic Comfort System combines Series GM™ boilers in single, multiple or modular arrangements with the Peerless® Partner® indirect-fired water heater, modern system controls, circulators and a design application guide to provide efficient, economical space and domestic hot water heating.

Modular vs. Multiple

Modular boiler systems require fewer limit controls and low water cut-offs than multiple boiler systems. On modular boiler systems, only one limit control on each boiler and one system limit control and low water cut-off are required. On multiple boiler systems, two limit controls are required on each individual boiler and, if the boilers are larger than 400 mbh input, a low water cut-off is also required on each boiler.

To qualify as a modular boiler system, ASME1 adds the following requirements versus a multiple boiler system:

  • Modules can be no larger than 400 mbh gas input (all Series GM™ boilers meet this requirement.)
  • No isolation or stop valves can be placed between modules and the main headers.

If ASME CSD-1 applies in your area, the low water cut-off(s) and additional limit control(s) must be manual reset.

Flex-Heat® System

Modular systems have higher overall boiler plant efficiency than typical single large boiler installations.

  • Higher part load efficiency – Atmospheric gas boilers operate most efficiently at full gas input rate. The FLEX-HEAT® system energizes each boiler at its full gas input and efficiency and controls the system by modulating the number of energized boilers.
  • Lower stand-by losses – Since the FLEX-HEAT® system energizes only the number of boilers needed to meet the heat demand, less heat is dissipated to the boiler room and less heat escapes up the chimney. FLEX-HEAT® Circulator Kits further reduce stand-by losses by preventing heated water from flowing through idle boilers.

Modular systems are redundant. If one boiler shuts down, the remaining boilers will provide heat until the problem boiler can be corrected. If a single boiler installation shuts down, it’s a no heat situation. Modular systems can also be easier to maintain. The Series GM™ boilers are pre-packaged and fit through a standard doorway, requiring less time to replace than changing a section of a single, large boiler.

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