Installation Guide

50 Rinnai Tankless Water Heater Installation and Operation Manual
Isolation valves are not supplied with the water
heater, but it is highly recommended to install
the isolation valves. The isolation valves (part
number MIVK-T-LW) provide the ability to
isolate the water heater from the structure’s
plumbing and allow quick and easy access to
flush the heat exchanger. The isolation valves
must meet American National Standard (ANSI
Z21.10.3) / Canadian Standard (CSA 4.3).
Water discharged
from the pressure
relief valve could cause severe burns
instantly or death from scalds.
An approved pressure relief valve is
required by the American National Standard
(ANSI Z21.10.3) for all water heating
systems and shall be accessible for
servicing. When connecting a pressure
relief valve, follow the guidelines below:
• The pressure relief valve must comply
with the standard for Relief Valves for
Hot Water Supply System, ANSI
Z21.22/CSA 4.4 or the ANSI/ASME
Boiler and Pressure Vessel Code
Section IV.
• The pressure relief valve must be rated
up to 150 psi and to at least the
maximum Btu/hr of the appliance.
• The discharge from the pressure relief
valve should be piped to the ground or
into a drain system per local codes.
• The pressure relief valve must be
manually operated once a year to check
for correct operation.
• The discharge line from the pressure
relief valve should pitch downward and
terminate 6 in. (152 mm) above drains
where discharge will be clearly visible.
WARNING
• The discharge end of the line shall be
plain (unthreaded) and a minimum of 3/4
in. nominal pipe diameter. The discharge
line material must be suitable for water at
least 180° Fahrenheit (82°C).
• The pressure relief valve must be
installed near the hot water outlet.
• The pressure relief valve is connected
below the appliance. DO NOT place any
other valve or shut off device between
the pressure relief valve and the water
heater.
• For safe operation of the water heater,
the pressure relief valve must not be
removed or plugged.
• If a pressure relief valve discharges
periodically, this may be due to thermal
expansion in a closed water supply
system. Contact the water supplier or
local plumbing inspector on how to
correct this situation. Do not plug the
pressure relief valve.
• The American National Standard (ANSI
Z21.10.3) does not require a combination
temperature and pressure relief valve for
this appliance. However, local codes may
require a combination temperature and
pressure relief valve.
• Protect pressure relief valve and
pressure relief valve discharge line from
freezing. Do not plug or restrict flow of
the pressure relief valve.
• DO NOT plumb the pressure relief valve
with the condensate drain; both must be
plumbed independently to drain.
• DO NOT plug the pressure relief valve
and do not install any reducing fittings or
other restrictions in the relief line. The
pressure relief line should allow for
complete drainage of the valve and the
line.
Pressure Relief Valve Maintenance:
For proper care of this approved pressure
relief valve, it is recommended that the valve
is manually operated once a year. In doing
so, it will be necessary to take precautions
with regard to the discharge of potentially
scalding hot water under pressure. Ensure
discharge water has a safe place to flow.
Contact with your body or other property may
cause damage or harm.