8 Maintenance (continued)

9.24VAC is supplied to the intermittent alarm field safety contacts, B1 and B2.

10.24VAC is supplied to the water flow switch.

11.24VAC is supplied to the TH terminals on the ignition module.

12.As power is applied to the TH terminals on the ignition module, 120VAC is switched from the F2 terminal to start the combustion air fan at full speed on Models 497 - 747 and at low speed on Models 987 - 2067.

13.24VAC is supplied to the C terminal of the air pressure switch. As the low air switch makes, power is supplied to the ignition module.

14.24VAC is then supplied to the PS terminals on the ignition module as the air pressure switch makes to prove fan operation.

15.The combustion air fan operates for the pre-purge period.

16.At the end of the pre-purge, 120VAC is applied to the hot surface igniter and the trial for ignition light.

17.The hot surface igniter proves 1800°F (982°C) ignition temperature by current draw through the ignition module.

18.The ignition module supplies voltage to the MV terminals on to the gas valve(s).

19.The first stage gas valve(s) opens and supplies gas to the orifice and burner inlet to pre-mix.

20.The gas/air mixture is forced into the burner and out of the burner ports under pressure.

21.The hot surface igniter lights the gas/air mixture and then serves as a flame sensor to prove main burner flame by rectification.

22.Burners are now firing for approximately 50% of the heater’s input.

23.24VAC is supplied from the second stage of the electronic temperature control across the 2C and 2NO terminals on the terminal strip on to a control to a relay.

24.The control relay switches the fan on Models 987 - 2067 to high speed and energizes the gas valves for the remaining 50% of burner input.

25.The remaining gas valves open and supply gas to the orifice inlet to pre-mix.

26.The gas/air mixture is forced out of the burner ports and light by carryover from the burners currently firing.

27.The heater is now firing at full rated input.

Installation & Service Manual

Heat transfer process

28.Heated products of combustion pass over the heat exchanger transferring heat to the water.

29. The rate of flue product movement is controlled by “V” baffles on the heat exchanger to maximize heat transfer.

30.Flue products pass into the flue collector and are exhausted from the unit.

End of sequence

31.Set point for the high fire on the electronic temperature control is satisfied.

32.Power to all valves is turned OFF on F9 systems and power to the high fire gas valves is turned OFF on M9 systems.

33.The water temperature continues to rise and the set point for low fire is satisfied (M9).

34.Power to the low fire gas valves is turned OFF (M9).

35.The combustion air fan runs for a 30 second post purge timing and turns OFF.

36.The appliance is now in a Standby Mode waiting for the next “call for heat”.

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Lochinvar 497 - 2067 service manual Heat transfer process, End of sequence
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497 - 2067 specifications

Lochinvar 497 - 2067 is a highly efficient and versatile condensing boiler that is designed to meet the diverse heating needs of residential and commercial applications. Known for its impressive performance and advanced technology, the Lochinvar 497 - 2067 has garnered a reputation as a reliable choice among heating professionals.

One of the standout features of the Lochinvar 497 - 2067 is its impressive thermal efficiency. The boiler boasts an efficiency rating of up to 95% AFUE (Annual Fuel Utilization Efficiency), allowing users to significantly reduce their energy costs while minimizing environmental impact. This efficiency is facilitated by its innovative condensing technology, which captures and reuses heat from exhaust gases for optimal performance.

The Lochinvar 497 - 2067 is equipped with a robust stainless steel heat exchanger designed to handle high temperatures and ensure long-lasting performance. The heat exchanger’s design maximizes heat transfer, while its corrosion-resistant properties guarantee durability over time. This contributes to the boiler's overall longevity and serviceability, reducing the need for frequent replacements.

Control is another critical feature of the Lochinvar 497 - 2067. The boiler comes with an advanced control system that enables easy management of system operations. Users can take advantage of features such as outdoor reset control, which adjusts the temperature of the boiler based on external weather conditions, enhancing system efficiency and comfort.

In terms of safety, the Lochinvar 497 - 2067 incorporates several cutting-edge safety features, including a flame detection system and multiple safety shut-off devices. These safeguards help to ensure the safe operation of the boiler, providing peace of mind to users and heating professionals alike.

Another important characteristic is the compact design of the Lochinvar 497 - 2067, which allows for flexible installation in various settings, including tight spaces. Its lightweight structure further simplifies the installation process, making it a practical choice for contractors.

In summary, the Lochinvar 497 - 2067 is an exceptional high-efficiency condensing boiler that combines advanced technology, durability, and ease of use. With its impressive thermal efficiency, superior heat exchanger design, advanced control systems, and enhanced safety measures, it stands out as a top choice for those seeking reliable heating solutions. This boiler not only meets but exceeds modern demands for energy efficiency and performance, solidifying its position in the market.
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