Rinnai RUC80i Installation And Operation Manual page 52

Recirculation Mode
Sequence of Operation
SW4 and SW8 in DIPSW 2 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
140
135
130
125
120
115
110
108
106
104
102
100
* 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.
KBD Series Manual
Typical Pump ON Intervals*
(minutes)
Economy
°F
Mode
31
31
31
31
31
35
42
45
49
54
60
68
98 79
Comfort
Mode
15
15
15
15
15
18
21
22
24
27
30
34
39