Demand Duo
™
H
-
Series Installation and Operation Manual
38
Water connections to the Commercial Hybrid
System should follow all state and local plumbing
codes.
If this is a standard installation, refer to section
“6.5
Piping Diagram for Basic Installations.
”
1.
Use of this layout should provide a trouble
-
free installation for the life of the water heater.
Before making the plumbing connections,
locate the
COLD
water inlet and the
HOT
water outlet.
•
The
COLD
water inlet is a 1
-
1/2 in. MNPT
fitting on the lower portion of the tank
below the tankless unit.
•
The
HOT
water outlet is a 1
-
1/2 in. MNPT
fitting located at the top of the tank. Install
a shut
-
off valve close to the water heater
in the cold water line. It is recommended
that unions be installed in the cold and
hot water lines so that the water heater
can be easily disconnected, if servicing is
required.
2.
When assembling the hot and cold piping,
use a good food grade pipe joint compound,
and ensure all fittings are tight. It is
imperative that open flame is not applied to
the inlet and outlet fittings, as heat will
damage or destroy the plastic lined fittings.
This will result in premature failure of the
fittings, which is not covered by the
warranty.
DO NOT OPERATE THIS WATER HEATER
UNLESS IT IS COMPLETELY FULL OF
WATER
. To prevent damage to the water heater,
all air must be relieved from the system and a hot
water fixture must be flowing water before the
water heater is plugged in and turned on. To
ensure safe and effective operation of the water
heater, use the following filling procedure. To fill
the water heater:
1.
Ensure the drain valve located at the bottom
of the tank is closed.
2.
Open the nearest hot water fixture in the
plumbing system.
3.
Open the cold water supply valve to the water
heater.
4.
Keep the hot water fixture open until the tank
is filled and constant flow is obtained at the
fixture.
5.
Check water heater connections and
plumbing system for damage or leaks. Repair
if needed.
NOTICE
DO NOT OPERATE THIS WATER HEATER
UNLESS IT IS COMPLETELY FULL OF
WATER.
•
The T&P relief valve must be rated up to 150
psi and to at least the maximum Btu/hr of the
appliance.
•
The discharge from the T&P relief valve should
be piped to the ground or into a drain system
to prevent exposure or possible burn hazards
to humans or other plant or animal life. Follow
local codes. Water discharged from the relief
valve could cause severe burns instantly,
scalds, or death.
•
The T&P relief valve must be manually operat-
ed once a year to check for correct operation.
Condensate can form in the vent of high
efficiency direct vent appliances. Without proper
drainage, condensate will damage the heat ex-
changer. Refer to Rinnai Tankless Water Heater
Installation and Operation Manual for condensate
guidelines.
To prevent condensate damage, follow these
instructions.
DO NOT
•
Do not connect the condensate drain pipe di-
rectly to the rain sewer.
•
Do not connect the condensate drain line with
an air conditioning evaporator coil drain.
•
Do not pipe condensate drain, temperature
-
pressure relief valve, and/or pressure relief
valve together into a common pipe.
•
Do not install an external condensate trap.
The tankless water heater has an integrated
condensate trap.
MUST DO
•
Use only venting that is approved and identi-
fied as acceptable for your particular model.
