A.O. Smith AWH-35, Instruction Manual, Page: 17 / 48

ELECTRICAL CONNECTIONS
CORRECT POWER SUPPLY!
Ensure the power supply at the job site matches the
voltage and phase listed on the HPWH rating label
before connecting power to the HPWH unit.
•
Damage caused to the HPWH as the result of applying
the wrong voltage or phase is not covered under the
limited warranty.
•
Energizing the HPWH with the wrong voltage or phase
will cause permanent damage to the HPWH unit.
•
CAUTION
CORRECT VOLTAGE AND PHASE
The HPWH units covered by this instruction manual can
be ordered with multiple power supply voltage and phase
configurations. Ensure the power supply voltage and phase
at the job site matches the power supply ratings listed on the
HPWH rating label BEFORE INSTALLATION BEGINS.
Voltage applied to the HPWH should not vary more than +5% to
-10% of the voltage requirement listed on the HPWH rating label
for satisfactory operation.
Energizing the HPWH with the wrong voltage and/or phase may
cause permanent damage to HPWH components. Damage
resulting from applying the wrong power supply voltage or phase
to the HPWH is not covered under the limited warranty.
Before removing any access panels or
servicing the water heater, make sure
the electrical supply to the water heater
is turned “OFF.”
Electrical Shock Hazard
•
Failure to do this could result in death,
serious bodily injury, or property
damage.
•
BRANCH CIRCUIT DISCONNECT SWITCH
The power supply wiring and equipment grounding must be
installed in accordance with local codes or, in the absence of
local codes, the National Electrical Code, ANSI/NFPA 70 or the
Canadian Electrical Code, CSA C22.1.
Install an adequately fused disconnect switch as close to the unit
as possible. See unit rating label for maximum fuse size (MFS).
Run the power supply lines from the disconnect to the control box
at the side panel of the unit. Connect the lines to the terminals on
input side of power distribution block L1 & L2 for single phase and
L1 , L2 & L3 f or three phase s . Connect ground wire to ground lug.
See Minimum Circuit Ampacity & Maximum Fuse Size on page
12 for wire, fuse and breaker sizing information.
TRANSFORMER CONFIGURATION 208 VAC MODELS
The transformer leads must be changed on units connected to
a 208 VAC power supply as described below. See Unit Wiring
Diagrams-Fuse Sizes on page s 32-36 for component locations .
BEFORE CONNECTING THE THERMOSTAT, turn on power to
the HPWH momentarily and measure the voltage to the primary
winding of the transformer at the F3 fuse block. If the measured
WATER CONNECTIONS
Water piping must be installed in accordance with the instructions
in this manual and all local plumbing codes having jurisdiction.
See Figure 7 and Figure 8 on page 18 and the Piping Diagrams
on page 4 1 as a reference for these instructions.
INSTALLATION INSTRUCTIONS
1. This HPWH unit is not designed to supply hot water directly
to hot water fixtures. The HPWH unit must be installed with a
separate storage tank as shown in the water piping diagrams
in this instruction manual.
2. Water lines installed between the storage tank and the HPWH
unit MUST NOT be less than the water pipe connection sizes
on the unit. See Table 4 on page 13.
3. T he HPWH should be plumbed directly to the storage tank.
4. The cold water supply must be connected directly to the
storage tank at a low connection port on the storage tank
on single tank and two tank preheat piping configurations for
optimal efficiency. See Figure 7 and Figure 8 on page 18 .
5. The cold water supply MUST NOT be connected the inlet
(entering/return) water line to the HPWH unit.
6. The outlet (supply) water from the HPWH unit should connect
to a middle or lower port on the storage tank.
7. The inlet (return) water from the HPWH unit should connect
to a port on the storage tank lower than the outlet.
8. A heat trap should be installed between the storage tank and
the backup water heater on two tank preheat systems. See
Piping Diagram on page 41 .
9. A T&P valve must be installed in the designated opening on
the storage tank per the tank manufacturer’s requirements.
See Temperature - Pressure Relief Valve on page 14.
10. Factory installed water pumps can provide the unit specified
water flow for up to a total of 50 equivalent feet of piping
between the HPWH unit and the storage tank. IE: 25
equivalent feet of inlet piping and 25 equivalent feet of outlet
piping. Do not exceed this maximum equivalent feet on
models equipped with factory-installed pumps.
11. For optimal performance minimize the equivalent length of
water piping between the HPWH and storage tank.
12. Building hot water recirculation loop should be connected to
the inlet of the backup water heater on two tank preheat
configurations or to the storage tank on single tank
configurations. The recirculating pump MUST BE controlled
by a field supplied thermostat installed in the building
recirculation return line near the storage tank or back up
heater. The thermostat should stop pump operation the
moment the recirculation line is hot.
13. Use swing-type check valves (not spring-loaded types) on
the water outlet lines of all HPWH units plumbed in parallel to
prevent hot water short-circuiting.
14. Water lines shared by parallel HPWH units must be large
enough to handle combined water flows. Flow rates through
the heat pumps and tank(s) must be balanced. See Table 1
on page 9 fo r HPWH unit flow rates.
voltage is above 215 VAC no changes are necessary.
If the measured voltage is 215 VAC or less, then the primary
leads of the transformer must be changed from the 230 VAC tap
to the 208 VAC tap. Do this by disconnecting the orange wire
from the transformer primary terminal and replacing with the
red wire. Before reapplying power, ensure orange lead is safely
isolated with a wire nut and electrical tape.
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