Transformer Protection; Using The Onboard Led To Determine Blower Cfm; Unit Operation With Two-Stage Cooling - Rheem RRNL Installation Instructions Manual

B. TRANSFORMER PROTECTION
The ECM interface board is equipped with an automotive-style 3 amp ATC blade fuse for
transformer protection. (See Figure 28.) If a short circuit occurs on the secondary side of the
transformer, the fuse will open.
C. USING THE ON-BOARD LED TO DETERMINE BLOWER CFM
The ECM interface board LED, which is located in the blower section (see Figure 28), indi-
cates blower output by flashing one (1) second for every 100 CFM of airflow. The LED will
pause 1/10 second between each flash. After the blower CFM has been displayed, the LED
will illuminate dimly for 10 seconds before repeating the sequence. (See Table 8.)
NOTE: If airflow is not a multiple of 100 CFM, the last LED flash is a fraction of a second of
100 CFM.
TABLE 8
LED FLASH CODES
Interface board
DIP switch
settiings
• Flashes 12 times
1200 CFM
• Illuminate dimly 10 seconds, repeat sequence
• Flashes 6 times
600 CFM
• Illuminate dimly 10 seconds, repeat sequence
• Flashes 9 times, flash once for
950 CFM
• Illuminate dimly 10 seconds, repeat sequence
D. UNIT OPERATION WITH TWO-STAGE COOLING
The RRRL unit provides distinct airflows for two-stage cooling. (See Figure 28.) Unit opera-
tion is defined as:
• Y1 – First Stage Cooling
• Y2 – Second Stage Cooling
A 24VAC signal provides input for the cooling stages.
NOTE: A 24VAC input to the Y2 terminal overrides the input to the Y1 terminal. (Both must be
energized to enable 2nd stage cooling.)
TABLE 9
TWO-STAGE OPERATION
Y1
INPUT
NONE
24 VAC
24 VAC
NONE
LED Output
1
/ second
2
Y2 COOLING
INPUT OPERATION
NONE OFF
NONE 1 ST STAGE
24 VAC 2 ND STAGE
24 VAC OFF
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