Fig. 28: Status LED Indicator Decal

Heater Sequence of Operation

Models 302B-902B

1.The black (hot) wire lead goes directly to the main power switch. This black toggle switch is located at the middle front of the control compartment.

2.When the main power switch is placed in the “ON” position, 120 VAC is applied to the 120 VAC termi- nal block on the circuit board and the 120/24 VAC transformer is powered.

3.120 VAC is waiting at the N.O. contacts of the Economaster pump delay.

4.Terminals L1 and F1 of the ignition module are powered with 120VAC.

5.120 VAC power is also applied to the control power connector on the circuit board.

6.120 VAC power is waiting at the N.O. contacts of K-3 relay to energize the heater blower.

7.The 120/24 VAC transformer outputs 24 VAC.

8.24 VAC is sent to pin L1 of the low water cut-off (optional) and the red power light is energized.

9.24 VAC is applied to the blue power light located on the status display board.

10.24 VAC is also applied to the red LED safety shut- down light on the front status board until the safeties have been proven.

11.24 VAC is applied to the alarm circuit (optional). If the E-5 sales option (Alarm) is included a 5 sec- ond time delay relay will not allow the alarm to sound unless a safety or limit circuit stays ener- gized for more than 5 seconds.

12.Power is applied to terminal P1-1 of the Universal Diagnostics Board. 24 VAC power is then applied in series to all typically closed safeties wired into the heater. All safeties are verified to ensure that it is safe to operate the heater. The safety compo- nents wired into the diagnostic board are: low water cut-off (optional), blocked vent switch, man- ual vent temp switch (optional), manual reset high limit, low gas pressure switch (optional), high gas pressure switch (optional), and auto-reset high limit (optional).

13.If any of the safeties do not close, a signal is sent to the Universal Diagnostics Board to indicate a safety fault.

14.Power is applied to terminal TP-1 of the Economaster pump delay to energize the circuit board.

15.Once all safeties are closed and verified, a 24 VAC signal is output from the Auto High Limit to J5 pin 3 of the CPW board of the heater.

16.24 VAC power is now sent to the coil of relay K-1.

17.Relay K-1 (N.C.) will now be energized, and opens the N.C. contacts to disable the alarm (optional) and turns off the red LED safety shutdown light on the front status board.

18.The common terminal of the Auto High Limit will now send a 24 VAC signal to pin 1 of the “panel switch”.

19.The “panel switch” (rocker switch) located at the lower left front of the control compartment is now powered. If the switch is “ON” and there is no call for heat (CFH), the heater is in standby mode.

20.After the standby switch is placed into the “ON” position, a 24 VAC signal is sent to the “enable/disable” connection (normally jumpered).

21.24 VAC switched power is applied to the S24V ter- minal on the ignition module.

22.When the “enable/disable” contacts are closed, the 24 VAC signal travels to pin 1 of the stage 1 connection and waits for a CFH.

23.When a CFH occurs, a 24 VAC signal is sent to the CFH light on the status panel located on the lower left front of the control compartment.

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Raypak manual Heater Sequence of Operation, Models 302B-902B
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302B, 902B specifications

Raypak is a prominent name in the heating industry, particularly known for its advanced technology and robust design in residential and commercial heating solutions. Two of their notable models, the Raypak 302B and 402B, exemplify innovation and efficiency in hydronic heating systems, designed to meet diverse needs while ensuring optimal performance.

The Raypak 302B and 402B are high-efficiency boilers that utilize gas-fueled systems. The 302B model has a heating capacity of 302,000 BTU/h, while the 402B boasts a maximum capacity of 402,000 BTU/h. This range of heating output makes these models suitable for a variety of applications, from residential heating needs to larger commercial spaces that require a reliable heat source.

One of the standout features of the Raypak 302B and 402B is their use of fire-tube heat exchanger technology. This design promotes efficient heat transfer and allows for lower emissions, thus minimizing the environmental impact. The fire-tube design also contributes to a longer lifespan and reduced maintenance costs, making these boilers a cost-effective solution over time.

Equipped with advanced control systems, the Raypak 302B and 402B ensure precise temperature regulation and improved energy usage. The digital display provides real-time feedback and diagnostics, enhancing user experience and simplifying troubleshooting. These models are also compatible with various building management systems, providing users with versatility in integration to optimize building performance.

In addition to their technological advancements, these boilers are designed with user safety and convenience in mind. They include features such as built-in safety controls, easy access for service and maintenance, and a compact footprint to fit into tight spaces. Their robust construction ensures durability, which is crucial for systems that operate under high demand.

Moreover, both models have been engineered to succeed in various climates, making them reliable choices for users in diverse geographical locations. With their energy-efficient operation, reliable performance, and advanced features, the Raypak 302B and 402B embody quality and innovation in the heating market, ensuring comfortable environments while lowering energy costs and environmental footprints.
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