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Indirect Fired Water Heater
Indirect Fired Hot Water Heater
Natural Thermal Circulating
300,000 to 3,000,000 BTU Gas Fired

Indirect Heating Principle & Diagram
The Basic Principle of indirect heating is accomplished by circulating the low temperature or circulating processed water through a copper tube heat transfer coil which is mounted internally and immersed in the primary Boiler water. The primary Boiler water is contained in a Bent Steel Tube Bundle and is heated in the furnace area, it rises to the upper header where the heat transfer into the secondary water occurs. The colder secondary water does not come into contact with high furnace temperatures or into contact with the flue gas at all. This eliminates any possibility of flue gas condensation which will occur on Direct Fired Heaters. Sweating and external corrosion of the Boiler Structure and tubes is essentially eliminated. The possibilities of scale, rust and corrosion are minimized by the indirect design principle. The furnace remains at a steady uniform temperature which results in high combustion efficiency and lower fuel consumption. This principle has proven more efficient and provides for a longer life as opposed to a direct system.

• Laundries
• Hotels
• Apartments
• Dairies
• Food Processing
• Hospitals
• Schools
• Swimming Pools
• Water Source Heat Pumps
• Low Temperature Process Water Applications
• Pond Heating
• Fish Farms
• Radiant Heating
• Nurseries

Indirect Fired Water Heater (Internal View)

Low NOx Premix
Indirect Fired Hot Water Heater
Natural Thermal Circulating
300,000 to 3,000,000 BTU Natural Gas or Propane Fired

Parker Boiler Premix Burner System
The Parker Boiler System consists of a burner bed of Heavy Duty Metal Fiber Burners (MFB). Through a gas/air premix manifold, the burners may be linked to a fully modulating blower mixer which offers precise control of combustion through the full range of modulation. Parker Boiler uses a variety of premix gas/air mixing & delivery systems for it's "L" System boilers. Parker Boiler's Low NOx Systems are typically designed for a 20 or 30 ppm level at 3% O2, however, special lower Low NOx boilers are available. In all cases, a Premixed gas/air is distributed to the burners by a manifold. By precisely controlling the gas/air ratio provided to the burners, Low NOx emission & efficient clean combustion is obtained.

Parker Boiler Premix Burner System 4
Variable Speed Drive Fan Post Mix System
Siemens SKP - Controller

Parker Boiler Premix Burner System 5
Variable Speed Drive Fan Post Mix System
Honeywell Valve/Venturi

Low NOx Hot Water Heater Insert (Internal View)

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NOTE: All drawing dimensions should be verified prior to installation. Due to continuous improvements and irregularities of purchased structural shapes and rounding, dimensions may vary and are subject to change without notice. If the model of the boiler you are looking for is not readily available here please contact Parker Boiler for more assistance at (323) 727-9800 from 8:00AM to 5:00PM (PST).

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