Rinnai RH180 selection, use, and review of the main characteristics. Find out how Rinnai water heater combined technology provides great savings and flexibility.
The RH180 water heater is actually known as the automatic circulating heater that consists of one large conventional water tank and a tankless unit that is attached to.
The heat exchanger is located in the tankless unit where cold water is heated to the set temperature and from there it is transferred to the storage tank by the circulating pump.
Both tankless and tank part of the system have the same elements as they would have as separate systems; the heat exchanger, fan, electric board, sensors, electric ignition, also anode rod, dip tube…
Rinnai offers only one model that is designed with the 40-gallon
tank capacity, but the first-hour rating is very high, 180 gallons per
hour and recovery at 90 F rise is 89 GPH.
The unit is used for heating potable water in residential applications, also for filling large or whirlpool spa tubs, for example. It cannot be used for manufactured homes or outdoor installations.
Incoming cold and outgoing hot water pipes are attached to the tank water heater while the gas piping to the tankless unit, where the gas control valve is.
Rinnai RH180 is factory set to use natural gas but can be converted
to use propane gas also, and the gas input, in this case, is slightly
lower; 91,300 BTU vs. 87,300 BTU.
Rinnai RH180 can only be installed indoor and it requires an adequate amount of air for gas combustion and dilution of flue gases.
air can be used either from inside or outside the building and the unit
gets it through the combustion air screen located at the front of the
Per manufacturer’s instructions, the water heater must be terminated vertically to the outside of the building, while it is not certified for side horizontal vent terminations.
The electric blower is used safely to move the flue gases through the 4-inch vent pipe (or larger) that is attached to the tankless unit. Due to the high thermal efficiency of over 80%, it results in lower flue gas temperatures.
The temperature controller is built-in into the front cover and it allows the temperature change in five settings: 1=110 F, 2=120 F, 3=130 F, 4=135 F and 5=140 F; while if there is a problem with the unit, the error code flashes (see the list of codes with the fix). The green led diode under the LCD display indicates when the water heater is in recovery mode. The buttons on the controller allow you to change the temperature, display the water flow and temperature of the incoming water.
|Storage Tank (Gal)||40|
|Power (Btu/hr)||59,500 - 91,300
(47,600 - 87,300)
|First Hour Rating (Gal)||180|
|Venting||4" UL B-Vent|
|Temp. settings (F)||110-140|
|Noise Level (dB)||50|
Combustion fan rpm check
Combustion air Carbon Monoxide sensor
Over current glass fuse
FVIR sensor that protects the heater from flammable vapors and the accidental ignition outside the combustion chamber
Freeze protection uses the pump to cycle warm water from the tank into the engine
Rinnai RH180 comes with the warranty of 10 years for the heat exchanger and 6 years on the storage tank.
Pictures - courtesy of Rinnai WH company