Installation Guide

64 Rinnai Tankless Water Heater Installation and Operation Manual

Rinnai CX Tankless Water Heaters include Circ-Logic technology that offers the comfort and

convenience of instant hot water with the use of an external recirculation pump. Circ-Logic controls

the on/off sequence and operation cycles of the external recirculation pump through the

programming of the tankless water heater’s parameter settings. Smart-Circ™ is the factory default

setting for recirculation. Smart-Circ™ allows the water heater to identify when hot water is used, and

then operates recirculation on subsequent days to reduce wait time for hot water. If a fixed

recirculation schedule is desired, then installation of an MC-195T-US Timer/controller or Wi-Fi

Module is required.

With residential units, the external pump cable is not included with the tankless water heater and

must be purchased separately. Circ-Logic operates in either Economy or Comfort mode based on

the parameter settings of the water heater.

• Economy Mode - Cycles the pump less often, using less energy to maintain the circulation loop

temperature.

• Comfort Mode - Cycles the pump more frequently, ensuring the loop temperature remains higher

(but also uses more energy).

Note: Rinnai offers an Internal Add-on Recirculation Conversion Kit (part number: RX2RXPCK) to

convert a no pump model to a pump model.

Rinnai Set Temperature

140 135 130 125 120 115 110 108 106 104 102 100 98

Parameter

Setting 01A

140 135 130 125 120 115 110 145 150 155 160 165 170 175 180 185

Parameter

Setting 01b

Typical Pump OFF Intervals (Minutes)

Economy

18 20 22 24 28 32 38 40 44 48 52 56 62 18 18 18 18 18 18 18 18 18

Comfort

9 10 11 12 14 16 19 20 22 24 26 28 31 9 9 9 9 9 9 9 9 9

Table 28

Components

within dashed

line are inside

water heater

FUSE

External

Pump

Harness:

Rinnai Part #:

105000250

Connect Ground (GN)

Wire to tankless housing

Figure 71

EXTERNAL

PUMP