Raypak 751 manual Diagnostics Board, Light Color Indication

U-2 Diagnostics Board

The U-2 Diagnostics board is a solid-state electronic fault indicator that has been engineered to enhance safety, simplify troubleshooting and minimize equip- ment down time. The U-2 safety board is the central point for wiring, operations monitoring, and fault indi- cation for the boiler safeties. By having each safety report directly to the U-2 board, each safety function can be individually monitored.

The U-2 adds complete diagnostics features that aid in the rapid diagnosis of irregularities in boiler operation. A single U-2 Diagnostics Board can monitor a maxi- mum of eight safeties at one time. If, due to code requirements, more than eight safety devices must be monitored, two or more boards will be used to provid- ed extended diagnostics capabilities. Advanced Design Boilers equipped with the standard safety suite will utilize the configuration shown in Table T.

The U-2 safety board has a series of red LED lights to indicate a fault occurring at a monitored safety. An

additional light indicates that the diagnostics board is energized and is currently monitoring for safety faults. (In order to prevent spurious alarm conditions, the U-2 board monitors safeties only during the actual firing cycle.)

Once a fault has been detected, the U-2 board will illu- minate the corresponding LED lamp, will shut-down the boiler, and will light the flashing red LED “Service” lamp on the CPW board. If more than one fault is detected, the U-2 board will display the priority fault based on the safety hierarchy as labeled on the U-2 board. Once the first fault is cleared, the second fault lamp will illuminate until cleared.

WARNING: Only qualified persons shall attempt to repair the boiler. Improper adjustment, service or maintenance may damage the equipment, create a hazard resulting in asphyxiation, explosion, fire, electric shock, personal injury or property damage, and will void the warranty.

Light	Color	Indication
System Enabled	Yellow	U-2 Diagnostics safety board is functional.
Manual High Limit	Red	Water temperature is over the manual high limit setting.
Auto High Limit	Red	Water temperature is over the auto high limit setting.
Flow Switch	Red	Water flow rate is too low.
Low Water Cut-off (option)	Red	Insufficient water volume for boiler operation.
High/Low Gas Pressure	Red	Gas supply pressure is below or above the allowed minimum gas supply
		pressure to ensure safe operation.
Burner High Limit	Red	Mixer or PVC vent pipe, if installed, is over heated.
Blower/Ignition Lockout	Red	Blower failure, not enough combustion air or the equipment has an ignition
		lock-out condition.
Blocked Vent	Red	The vent pressure switch has detected a blocked vent.

Table T: U-2 Diagnostic Board LEDs

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