A.O. Smith AWH-35, Instruction Manual

Page: 19 / 48

19
DIGITAL TANK THERMOSTAT INSTALLATION
1. Mount the thermostat on the storage tank jacket when or at
a suitable location close to the storage tank, see Figure 10.
2. Install three conductor low voltage wiring between the
thermostat’s terminal strip and the HPWH unit’s terminal
strip as shown in the Digital Tank Thermostat Wiring on page
37 . Use standard 18 AWG thermostat wire or equivalent.
TEMPERATURE SENSOR INSTALLATION
The HPWH unit is shipped from the factory with a Digital Tank
Thermostat that includes a Temperature Sensor and a Sensor
Well. To install the Sensor Well:
1. Coat the Temperature Sensor and the inside of the Sensor
Well with heat transfer compound (paste) such as Honeywell
P/N 107408 or equivalent.
2. Secure the Temperature Sensor inside the Sensor Well with
the supplied clip or with an appropriate stop.
3. Check the condition of the anode rod(s) on existing storage
tanks and replace if depleted.
4. Install the sensor well in the storage tank’s designated
temperature control opening. Typically a 3/4” female NPT
fitting in the lower portion of the storage tank.
5. DO NOT install Sensor Well or temperature sensor in the
upper half of the storage tank.
6. Do not install Sensor Well near the cold water supply
connection to the storage tank to prevent short cycling.
7. Install two conductor low voltage wiring between the
Temperature Sensor and Digital Tank Thermostat terminal
strip as shown in the Digital Tank Thermostat Wiring on page
37 . Wiring can be installed up to 650 feet using 24 AWG
thermostat wire or equivalent.
REMOTE TEMPERATURE
SENSOR AND SENSOR WELL
HPWH
BACKUP
WATER
HEATER
DIGITAL TANK
THERMOSTAT
STORAGE
TANK
Figure 10
AIR FLOW AND DUCTING
GENERAL GUIDELINES
Review Locating The Water Heater on page 10, and this
section prior to connecting ductwork to the HPWH. See Features
And Components on page 8 to locate components.
Do not duct air from a garage or other
space where potentially harmful fumes
from solvents, chemicals or exhaust
from automobiles are present into any
other space in the building structure.
Gas and carbon monoxide detectors
are available.
Breathing carbon monoxide can cause brain damage or
death. Always read and understand instruction manual.
Breathing Hazard - Carbon Monoxide Gas
The supply (outlet) air from a HPWH installed in a garage or a
unit drawing return (inlet) air from a garage or any area where
solvents or other chemicals that emit potentially harmful fumes
are stored or automobiles are located must never be ducted to
any other space inside the building structure. This would include
all occupied and unoccupied spaces such as attics or basements.
Potentially harmful fumes and vapors could be introduced into
occupied spaces. See Unit Placement on page 16.
DUCT SIZING
Supply and return air ducting must be sized properly to insure
adequate airflow. Table 6, Table 7 and Table 8 on page 21
provide requirements for the total equivalent supply and return
duct lengths allowed. These tables are based on the most
common duct material options available today. Exceeding those
maximum lengths will adversely affect the operation of the heat
pump.
DUCT INSULATION
The cooled air from the HPWH may be below room dew point.
Insulate the supply duct to prevent dripping from moisture
condensing on the duct.
It is not necessary to insulate return ducts unless the air in the
return duct is lower than the room air. Also consider insulating all
ductwork to reduce blower noise from the unit.
MAKE DUCT CONNECTIONS
Install all ductwork to and from unit in accordance with all
applicable codes. Duct construction must allow unit to operate
within the limits of the unit external static pressure as in the
HPWH unit’s performance and specification sheets. See Table
1 on page 9 also.
Use flexible connections to minimize duct-to-duct alignment
problems and noise transmission.
Install ductwork, accessory grilles, and plenums so that they do
not restrict access to filter and so they prevent dirt, dust, and
debris from settling in unit.
BUILDING AIR PRESSURE
When installing ducting to or from an alternate location (other
than the installed space) both the supply (outlet) and return
(inlet) air may need to be ducted to prevent positive or negative
building air pressure conditions within the installed space.