Rinnai COMBI i060C, Installation And Operation Manual, Page: 94 / 136

94 Rinnai I-Series Condensing Boiler Combi Manual
CROSSOVER MODE
Dedicated mode — Home includes a dedicated
circulation return line in the plumbing system.
Crossover mode (factory default) — Home does
not include a dedicated circulation return line.
Requires installation of a thermal bypass valve at
the furthest fixture in the plumbing system.
DEDICATED MODE
This boiler has the capability to control DHW recirculation. While the default setting for
recirculation is “off,” when DIP switch 3 is turned “on,” the DHW recirculation function becomes
available.
When utilizing the domestic hot water recirculation function, the pump must be wired to the Pump
2 terminal on the PC Board. Therefore, if two central heating zone pumps are used, an external
central heating zone controller is required.
During the DHW recirculation operation, the boiler will be in DHW operation mode. To prevent the
central heating (CH) system from being inactive too long and the house potentially cooling down,
the boiler will operate in simultaneous operation between DHW and CH as long as the DHW
recirculation is taking place.
If the output target temperature for the CH system is higher than the temperature needed to heat
the DHW, the CH supply temperature will not be affected. The CH supply temperature will continue
to be the target temperature set for CH.
If the output target temperature for the CH system is less than the need to heat DHW, the supply to
the CH system will increase to the water temperature needed for DHW.
Rinnai strongly recommends installing insulation to the hot water and
dedicated return lines to decrease the amount of heat loss.
IMPORTANT
Two recirculation modes are available: Crossover and Dedicated.
The temperature restriction can be canceled by adjusting Parameter 14. If
adjusted to "No" temperature restriction, ensure that the CH system and
heat emitters are designed for the hot water temperature supplied to the domestic plate heat
exchanger (typically 149°—185°F).
Failure to do so could cause damage to the CH system, heat
emitters, or building in which the system is installed.
CAUTION