Raypak 751 Operations Instructions download pdf (Page 43)

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 noitacidnIroloC

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.

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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

1 2 ... 38 39 40 41 42 43 44 45 46 47 48 ... 56 57

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Raypak 751 Operations Instructions Page 43

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