Rinnai RH180 User manual

Rinnai RH180 Hybrid Tank –
Tankless Water Heater
Installation Fundamentals, Level II
1

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RH180 Hybrid Tank-Tankless Water Heater
Level II Training Program
Installation Fundamentals

RH180 Technology
4
+=
Combining Technologies:
With the combination of a tank and a Rinnai tankless water heater into
one appliance, the RH180 hybrid provides increased hot water capacity
with the ease of a tank installation.

• Circulation pump for
tank/engine
• Hot water supply from
engine to tank
• Cold water supply
from tank to engine
• Tankless water heater
engine
• 40 gallon storage tank
• ¾” cold water supply
into tank
• ¾ hot water feed
into building
• Pressure relief valve
• 4” B-vent exhaust
connection
• Combustion air inlet
and filter
• Tank drain valve
• Temperature controller
• 120 Volt power cord
(not shown)
Product Component Identification
5
• Gas connection

RH180
Sequence of Operation
6

Sequence of operation:
7
1. When the water temperature at the bottom of the tank (at the tank
therm stor) drops to a pre-determ ned temperature, the startup
sequence w ll beg n.
2. The tankless eng ne’s combust on fan w ll beg n turn ng, draw ng
fresh a r from the space. Th s w ll allow the flammable vapor sensor
to ensure the ntake a r s free of combust ble vapors.
3. The pump w ll beg n c rculat ng water through the tank-tankless
loop.
4. The eng ne w ll f re when t detects the water flow from the pump.
5. The heated water from the eng ne w ll be depos ted back nto the
tank. The water w ll be d rected toward the top of the tank close to
where hot water s be ng drawn nto the plumb ng system.
6. In t ally as water s drawn from the tank nto the eng ne, the Delta T
w ll be fa rly large and the eng ne w ll operate n a h gh f re mode.
7. As the water at the bottom of the tank beg ns to heat, warmer
water w ll then beg n to enter the eng ne — th s w ll reduce the
Delta T allow ng a h gher flow rate through the eng ne.
8. As the water n the tank cont nues to warm and gets closer to the
set temperature, the tankless eng ne w ll automat cally reduce ts
gas nput.
9. When the temperature at the bottom of the tank reaches the set
po nt, the pump turns off — the tankless eng ne w ll go nto a
standby mode unt l the next start sequence.
9.
6.
3.
5.
2.
8.
4.
7.
1.

RH180
Water Heater
Sizing
8

RH180 Sizing
Water Heat ng
Opt ons
Max nput (Btuh
/ Kwh)
Tank Capac ty
(gal.)
T me of ava lable
hot water (m n.)
T me of ava lable
hot water (m n.)
Recovery t me
(m n.)
Showers In use
at one t me 70⁰ temp r se 70⁰ temp r se 70⁰ temp r se
Electr c Tank 4.5 Kw 40 21 10 88
Gas Tank
34,000 Btu 40 18 8 36
40,000 Btu 50 26 11 40
75,000 Btu 75 50 19 32
R nna RH180
Hybr d
Tank -Tankless
91,300 Btu 40 Cont nuous 11 16
R nna Tankless Up to 199,000
Btu N/A Cont nuous Cont nuous N/A
•Data is based on a 50⁰F inlet water temperature and a 120⁰F hot water set point (70⁰F rise).
•Shower heads assumed to be 2.5 gpm mixed low rate with 105⁰F at the ixture.
•Available hot water time and recovery time based on industry standard calculation methods
and Rinnai lab testing. Actual results may vary based on the application.

RH180
Product Features &
Safety devices
10