Rinnai RU80i Installation And Operation Manual page 52

Recirculation Mode
Sequence of Operation
DIP switches (SW2 - white switches, #4, #8) should be
set correctly for recirculation and mode. The Rinnai
water heater should be turned on.
Pump recirculation begins when the water heater is
turned on. The Rinnai inlet and outlet thermistors
measure the water temperature.
The water heater produces hot water at the
temperature setting. If the inlet thermistor detects
abnormal temperature then diagnostic code 51 is
generated and the pump will turn off.
When the return water temperature reaches
approximately 15°F (8.3°C) below the temperature
setting, the water heater and pump will turn off.
The cycle will restart at the approximate time interval
in the table based on the temperature thermistor
readings.
Economy Mode
The Economy mode operates as follows:

Less energy consumed due to fewer pump cycles

Assumes plumbing is insulated (minimal pipe heat
loss)

Pump cycles on every 31 to 79 minutes (see
table).
Comfort Mode
The Comfort mode operates as follows:

Higher energy consumption due to more pump
cycles

Assumes plumbing is not insulated resulting in
higher pipe heat loss

Pump cycles on every 15 to 39 minutes (see
table).
52
Rinnai
Temperature
Setting
°F
140
135
130
125
120
115
110
108
106
104
102
100
98
* The pump will cycle on at these calculated
intervals which are based on the temperature
setting, insulation, and estimated heat loss in the
system. The values for your installation may vary.
The optional MC195T-US controller provides a timer
function to control the on/off periods of the recircula-
tion pump.
KB Series Manual
Typical Pump ON Intervals*
(minutes)
Economy Comfort
Mode Mode
31 15
31 15
31 15
31 15
31 15
35 18
42 21
45 22
49 24
54 27
60 30
68 34
79 39