Series 900 Combination Boilers

Series 900 Combination Boilers Overview: Triad Series 900 Boilers for Combination applications are ready-to-install packaged systems featuring a perfectly matched powerful and efficient burner and boiler combination. All necessary boiler controls and secondary plumbing are in place and pre wired, and the vessels easily fit through a 32" doorway, resulting in a very quick start-up.

Each vessel contains a 97 foot copper coil through which the domestic hot water is circulated. This coil is surrounded by the hot boiler water, which transfers heat to the coil.

Firing rates for the Series 900 Combination Boiler are available from 600,000 Btu/hr to 1,000,000 Btu/hr. However, many millions of Btu’s can be delivered by creating an efficient, fully modular system of up to 24 vessels operated by our computerized control panel.

Design: The Series 900 Combination Boiler is manufactured to exceed ASME Section IV standards and typically is used to provide water temperatures of between 60-130°F.

These vessels contain 73 vertical firetubes, each of which is 1½" diameter, each fitted with a high-efficiency turbulator for maximum heat transfer. The combustion chamber is fully water-backed, with burners that are UL listed. The vessel capacity is 75 gallons with a heating surface of 78 sq. ft.

This boiler qualifies as a Category I gas appliance with industry standard controls wired to NEC specifications.

Safety: A well-made, heavy vessel is naturally a safer boiler. But TRIAD Boilers also have a firebox design that is completely backed by water, along with extra safety controls on the boiler that results in a very safe and secure package.

Standard Features: The following standard features include nationally known parts and controls that are available at most supply houses, allowing for quick and easy repair and maintenance, which can dramatically reduce down time:

  • UL Listed Gas Trains and Control Systems.
  • Choice of Power Burners.
  • Main and Auxiliary Gas Valves
  • Air Flow Switch
  • Main Manual Leak Test Valve
  • Bell and Gossett Circulating Pump
  • Second Bell and Gossett Pump for Coil
  • Honeywell Aquastat Relay
  • Automatic Low Water Cutoff
  • Honeywell Second High-Limit With Manual Reset.
  • Burner Control Relay.
  • High Visibility Operating Light.
  • Pressure/Temperature Gauge
  • Pressure Relief Valve
  • 1½" Diameter Firetubes of SA178-A Steel
  • Turbulators for Maximum Heat Transfer
  • Two Inches of Insulation With a Painted Steel Jacket.


Boiler Efficiencies:
Model Input
(BTU/Hr)		 Gross
OutPut		Combustion
Efficiency		 GPM @
Riseº F		Pressure
Drop Thru
the Coil
600 600,000 508,80085.0% 20.3 @ 50º F2.86
700 700,000 589,40084.0% 23.6 @ 50º F3.53
800 800,000 664,80083.0% 26.7 @ 50º F4.53
900 900,000 746,10083.0% 29.8 @ 50º F5.65
1,000,000 N/A N/AN/A N/A


Options: TRIAD offers several options to customize your boiler. A job is not complete until the boiler has been properly equipped for the application.

  • Choice of burner manufacturers fired by natural gas, oil, propane, or combination fuel.
  • Spark Ignition System for Combination Fuel Burners
  • Low-High-Low firing
  • CSD-1, IRI, FM
  • Low-High Gas Train with Motorized Valves
  • Fan-Damper relays
  • Louver Box for Sealed Combustion Side-Wall Venting
  • Barometric Dampers and Galvanized Tees
  • Clean-out openings and plugs
  • Microprocessor Control Panel for true lead-lag modulation
  • Factory built and customized primary mains and headers
  • Immersion Aquastats
  • Various Relief Valve sizes for different applications
  • Lifting Lugs
  • Rail Legs


Boiler Dimensions:
Feature Dimension
  Vessel Width 30.5"
  Vessel Height 66"
  Boiler Weight 1400 lbs
  Boiler Depth w/ Burner 61"
  Gas Inlet Height 12"
  Return Water Inlet Height 9"
  Top of Vessel to Bottom Main 9"
  Height to Lower/Upper Coil Openings 35.25"/56"
  Height to Pump Flange 38"
  Height to Space Heater Return 23.5"
  Height Required at Installation 90"
  Clearance to Rear of Boiler 18"
  Clearance to Front of Boiler 48"
  Clearance to Side of Boiler 18"
  Clearance Between Boilers 6"