Condensing Boiler features fire-tube technology

Lochinvar’s CREST condensing Boiler offers fire-tube innovation, touch screen technology

02/08/2011


Lochinvar CREST BoilerLochinvar’s CREST Condensing Boiler features fire-tube technology integrated with the exclusive SMART TOUCH operating control, allegedly offering engineers, mechanical contractors and building owners greater design flexibility and distinctive performance characteristics to meet today’s building standards for new construction and energy retrofit applications. Available in five models that range from 1.5 to 3.5 million Btu/hr, with thermal efficiencies reported as high as 99 percent, CREST brings Lochinvar’s leading-edge technology and exceptional energy-efficiency to the largest commercial applications.

The CREST Combustion System

The fully modulating CREST Condensing Boiler introduces a low-NOx combustion system with a stainless steel heat exchanger and a purportedly unique, patent pending dual-system burner design with up to 25:1 turndown. The top-mounted, single micro-metal fiber burner actually serves as two combustion systems in one, each with its own blower and gas valve assembly to power the combustion process based on demand. For example, in a two million Btu/hr CREST Boiler, the upper portion of the burner fires first, with 5:1 turndown, and modulates from 80,000 to 400,000 Btu/hr. When demand exceeds 400,000 Btu/hr, the lower portion of the burner fires and modulates from 320,000 to 1.6 million Btu/hr. In addition, both burners can fire together and modulate up to the maximum two million Btu/hr input.

Introducing the Wave

The Wave 316L stainless steel fire-tube is larger than other reportedly industry fire-tubes, which means CREST requires fewer tubes and welds. Its exclusive design and unique wave pattern provides superior heat transfer in every fire-tube, creating turbulence to “scrub” maximum heat energy from the flue gas products before they leave the heat exchanger.

Each fire-tube is welded into the CREST’s heat exchanger vessel and surrounded by water. The burner fires heat energy and combustion products downward into the fire-tubes, which transfer the heat to the water flowing up inside the vessel. With one pass, the heat is stripped from the flue products, bringing the water to condensing temperatures as it flows out into the system. Condensate is drained into a stainless steel collector and piped to a suitable drain in the floor, while exhaust vents through the bottom of the unit.

SMART TOUCH + CREST

CREST is equipped with Lochinvar’s SMART TOUCH user control, an operating system loaded with features and benefits that provide ease of installation, operation and data retrieval. Its technology offers control and monitoring via the eight-inch, multi-color touchscreen display. In addition, SMART TOUCH enables CREST to communicate and in real time with building management systems by utilizing an on-board MODBUS protocol.

Another benefit of the SMART TOUCH operating system is its built-in cascading sequencer. CREST is capable of sequencing up to an eight boiler system using a simple two-wire, daisy-chain connection, which eliminates using a separate, third-party sequencer. One boiler functions as the leader and modulates to capacity. Increasing load then cascades to additional “lag” boilers in the sequence as needed. This lead-lag rotation shifts the “first on” boiler every 24 hours, distributing equal run times to each unit.

The ability to sequence up to eight boilers that each have as much as 25:1 turndown means that the combined system has the potential of operating with modulation of up to 200:1 turndown. A bank of eight two million Btu/hr CREST models can provide as little as 80,000 Btu/hr and as much as 16 million Btu/hr of heating output, resulting in greater seasonal efficiencies.

Low on Flow Rates, High on Venting Flexibility

CREST allows system designers flexibility to vary the flow rate through the boiler. With options for installation with primary/secondary piping or in a full-flow arrangement, CREST can operate at flow rates as low as 20 GPM up to a full 350 GPM flow rate, which means it can service systems that operate with fluctuating flow rates depending on demand.

In addition, CREST offers a variety of horizontal and vertical venting options with increased vent lengths and configurations. With six unique venting options, CREST provides flexibility for placement of units within the building as it permits direct-vent air intake and exhaust runs up to 100 equivalent feet.

Typical Specifications (DOC)

Lochinvar Corporation



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