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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Type: Semi-Commercial/Commercial
Construction: Cast Iron
Fuel: Gas-Fired (Natural or LP)
Input: 456 to 3,990 MBH
Output: 374 to 3,272 MBH
Venting: Natural Draft
Trim: Water
Ignition: Standing Pilot or Intermittent

 

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System Number Module Quantity & Size Input (MBH) Gross Output (MBH) Gross Output (H.P.) Net Output (MBH) Combustion Efficiency
FH-456 2-5 456 374 11.2 325 82%
FH-513 1-5, 1-6 513 421 12.6 366 82%
FH-570 2-6 570 467 14.0 406 82%
FH-627 1-6, 1-7 627 514 15.4 447 82%
FH-684 2-7 684 561 16.8 488 82%
FH-741 1-7, 1-8 741 608 18.2 528 82%
FH-798 2-8 798 654 19.5 569 82%
FH-855 3-6 855 701 20.9 610 82%
FH-912 2-6, 1-7 912 748 22.3 650 82%
FH-969 1-6, 1-7 969 795 23.7 691 82%
FH-1026 3-7 1026 841 25.1 732 82%
FH-1140 1-7, 2-8 1140 935 27.9 813 82%
FH-1197 3-8 1197 982 29.3 854 82%
FH-1254 2-6, 2-7 1254 1028 30.7 894 82%
FH-1368 4-7 1368 1122 33.5 975 82%
FH-1482 2-7, 2-8 1482 1215 36.3 1057 82%
FH-1539 1-7, 3-8 1539 1262 37.7 1097 82%
FH-1596 4-8 1596 1309 39.1 1138 82%
FH-1710 5-7 1710 1402 41.9 1209 82%
FH-1824 3-7, 2-8 1824 1496 44.7 1301 82%
FH-1881 2-7, 3-8 1881 1542 46.1 1341 82%
FH-1938 1-7, 4-8 1938 1589 47.5 1382 82%
FH-1995 5-8 1995 1636 48.9 1423 82%
FH-2052 6-7 2052 1683 50.3 1463 82%
FH-2166 4-7, 2-8 2166 1776 53.1 1544 82%
FH-2280 2-7, 4-8 2280 1870 55.9 1626 82%
FH-2394 6-8 2394 1963 58.6 1707 82%
FH-2508 5-7, 2-8 2508 2057 61.4 1788 82%
FH-2622 3-7, 4-8 2622 2150 64.2 1870 82%
FH-2736 1-7, 6-8 2736 2244 67.0 1951 82%
FH-2793 7-8 2793 2290 68.4 1992 82%
FH-2850 6-7, 2-8 2850 2337 69.8 2032 82%
FH-2964 4-7, 4-8 2964 2430 72.6 2113 82%
FH-3021 3-7, 5-8 3021 2477 74.0 2154 82%
FH-3078 2-7, 6-8 3078 2524 75.4 2195 82%
FH-3192 8-8 3192 2617 78.2 2276 82%
FH-3306 5-7, 4-8 3306 2711 81.0 2357 82%
FH-3363 4-7, 5-8 3363 2758 82.4 2398 82%
FH-3420 3-7, 6-8 3420 2804 83.8 2439 82%
FH-3534 1-7, 8-8 3534 2898 86.6 2520 82%
FH-3591 9-8 3591 2945 88.0 2561 82%
FH-3648 6-7, 4-8 3648 2991 89.4 2601 82%
FH-3762 4-7, 6-8 3762 3085 92.2 2682 82%
FH-3876 2-7, 8-8 3876 3178 94.9 2764 82%
FH-3990 10-8 3990 3272 97.7 2845 82%

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Series GM™ Boiler Dimensions

Boiler Model Number Jacket Depth
"A"
Jacket Width
"B"
Jacket Height
"C"
Left of Jkt. to C/L of Vent
"D"
Top of Jkt. to Vent Connector
"E"
Vent Size
"F" Dia.
USA, Nat. Gas Canada or LP
GM-05 25-3/4" 19-1/4" 35-1/4" 9-3/4" 29" 7" 8"
GM-06 25-3/4" 22-3/4" 35-1/4" 11-1/2" 30" 8" 9"
GM-07 25-3/4" 26-1/4" 35-1/4" 13-1/4" 31" 9" 10"
GM-08 25-3/4" 29-3/4" 35-1/4" 15" 31" 9" 10"

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