Installation & Operation Manual

10 Operating information

Sequence of operation

Note: This unit is equipped with two (2) gas train systems. Gas Train 1 will fire first. If the demand cannot be met by the first gas train, the second gas train (Gas Train 2) will fire.

1.Upon a call for heat, the control turns on the appropriate pumps (system and boiler pumps for a space heating call, HW pump for a domestic hot water call).

2.The control confirms that the low water cutoff contacts are closed and energizes the louvers (optional) and damper (optional) relays.

3.The control confirms that the gas pressure switch, blocked drain switch, limits, louver proving switch (optional) and damper proving switch (optional) contacts close. The Pre-Purge cycle begins.

4.The control confirms both blowers come up to the desired speed, both blower proving switches close, and the air pressure switch is closed.

5.Once the Pre-Purge cycle is complete, the control lowers the blower speeds, initiates sparking of the ignition electrode, and opens Gas Valve 1.

6.After a short wait, the control stops sparking and checks for the presence of flame current through the flame sense electrode.

7.If the control does not detect flame current, the control will lockout indefinitely, until the RESET button on the touch screen LCD is pressed. Models FB 1500 - 2500 will have one retry.

If the control detects flame current, the control will hold the blower speed constant for a few seconds to allow the

8.flame to stabilize, then begin modulating the firing rate in order to maintain the controlling sensor to the desired set point temperature.

If the current call for heat is for space heating and a HW call for heat becomes active, the control will turn on the HW

9.pump relay output, then turn off the boiler pump. It will then modulate the blower speed in order to maintain the outlet temperature to the desired HW outlet set point temperature.

If the first combustion system in the boiler is unable to maintain the desired set point temperature, the second combustion system in the boiler will be started. Both blowers will modulate to a set speed, and the second gas valve

10.will be energized. The second combustion system will light from the first combustion system. The second flame will be monitored much like the first. Once both combustion systems are firing, the control will work in synchronization to maintain the desired set point temperature. If the heat load should decrease sufficiently, the second combustion system will be shut down.

11.Once both the space heating and HW calls for heat are satisfied, the control will turn off the gas valve(s) and begin the Post-Purge cycle. Any pumps that are running will begin their respective Pump Delay cycles.

12.At the end of the Post-Purge cycle, the louver relay contacts will de-energize.

13.The control verifies that the blowers stop running and the blower proving switches open.

14.At the end of the Pump Delay cycle(s), the pump(s) will be turned off.

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Lochinvar 2.5, 3.5 service manual Sequence of operation
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3, 2, 3.5, 2.5 specifications

The Lochinvar 2, 3, 3.5, and 2.5 models are a standout lineup in the realm of commercial and residential water heating solutions. Known for their advanced technology and high efficiency, these units cater to a wide range of applications, ensuring optimal performance and reliability.

One of the key features of the Lochinvar models is their robust construction. Each unit is designed to withstand rigorous operational demands while providing excellent thermal efficiency. They are equipped with stainless steel heat exchangers, which offer superior resistance to corrosion and extend the lifespan of the equipment. This durability is essential for both commercial and residential settings where demand can vary significantly.

The Lochinvar 2, 3, 3.5, and 2.5 models utilize innovative control systems that enhance their operational efficiency and user convenience. The built-in Smart Control technology allows for easy monitoring and adjusting of system parameters, ensuring that users can maintain optimal performance with minimal effort. This feature is especially beneficial in commercial settings where large volumes of hot water are required, as it enables users to effectively manage their energy consumption.

Energy efficiency is another hallmark of the Lochinvar lineup. With high-efficiency ratings, these models help reduce energy costs significantly, making them an environmentally friendly option for heating water. The use of advanced combustion technology ensures that these units can deliver maximum heat output with minimal fuel consumption.

Additionally, the Lochinvar models are designed with safety and reliability in mind. They feature multiple safety controls and diagnostics that alert users to potential issues before they escalate, providing peace of mind. The integration of advanced venting options allows for flexible installation configurations, accommodating various building layouts and space requirements.

In summary, the Lochinvar 2, 3, 3.5, and 2.5 models define modern water heating technology with their combination of durability, efficiency, and advanced features. With their innovative design and user-friendly controls, they meet the demanding needs of both commercial and residential users, making them a top choice in the water heater market. Whether for new installations or replacements, these units deliver reliable performance and value.
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