How To Use The Temperature Controller - Rinnai RUC80i Operation Instructions Manual

How to use the Temperature Controller

The MC-91-2 controller is the standard temperature controller
that is supplied with the water heater. On indoor models it is
integrated into the front panel. The MCC-91-2 controller is for
commercial and hydronic applications requiring higher
temperatures. When the MCC-91-2 controller is connected,
these higher temperatures are available on all controller
models in the system. Refer to the section on temperature
ranges.
DO NOT repeatedly operate the water heater and then use a
hot water tap while the controller is turned off. Operating the
water heater in this way to alternately produce hot water may
cause water to condense on the outside of internal parts and
accumulate in the water heater cabinet.
WARNING
 Before operating, smell all around the appliance area for
gas. Be sure to smell next to the floor because some gas
is heavier than air and will settle on the floor.
 Keep the area around the appliance clear and free from
combustible materials, gasoline, and other flammable
vapors and liquids.
 Always check the water temperature before entering a
shower or bath.
 Do not use this appliance if any part has been under
water. Immediately call a licensed professional to
inspect the appliance and to replace any part of the
control system and any gas control which has been
under water.

Should overheating occur or the gas supply fail to shut
off, turn off the manual gas control valve to the
appliance.

Do not adjust the DIP switch unless specifically
instructed to do so.
The water must be potable, free of corrosive chemicals, sand, dirt, or other contaminates. It is up to the installer to
ensure the water does not contain corrosive chemicals, or elements that can affect or damage the heat exchanger. Water
that contains chemicals exceeding the levels below affect and damage the heat exchanger. Replacement of the heat
exchanger due to water quality damage is not covered by the warranty.
Total Hardness
Aluminum *
Chlorides *
Copper *
Dissolved Carbon Dioxide (CO2)
Iron *
Manganese *
pH *
TDS (Total Dissolved Solids) *
Zinc *
3 of 17
In Use
Indicator
Temperature
Display
Temperature
Selection
MC-91-2US
Dimensions (inches): 3.5 W x 4.75 H x 0.75 D

Do not use an extension cord or an adapter plug with
this appliance.
 Any alteration to the appliance or its controls can be
dangerous and will void the warranty.

If you install this water heater in an area that is known
to have hard water or that causes scale build-up the
water must be treated and/or the heat exchanger
flushed regularly. Rinnai provides a "Scale Control
System" that offers superior lime scale prevention and
corrosion control by feeding a blend of control
compounds into the water supply. Damage and repair
due to corrosive compounds in the air is not covered by
warranty.

Keep the air intake location free of chemicals, such as
chlorine or bleach, that produce fumes. These fumes
can damage components and reduce the life of your
appliance. Damage and repair due to scale in the heat
exchanger is not covered by warranty.
Maximum Level
Up to 200 mg / L
Up to 0.2 mg / L
Up to 250 mg / L
Up to 1.0 mg / L
Up to 15.0 mg / L or PPM
Up to 0.3 mg / L
Up to 0.05 mg / L
6.5 to 8.5
Up to 500 mg / L
Up to 5 mg / L
Priority
Indicator
Priority
Button
ON/OFF
Button
* Source: Part 143 National
Secondary Drinking Water
Regulations