John Wood Commercial - 300-400K BTU - Manual (Page 13)

13
4. When installing multiple water heaters in the same gas supply
system it is recommended that individual positive lock-up gas
pressure regulators be installed at each unit.
power supply
The water heaters covered in this manual require a 120 VAC,
1Ø (single phase), 60Hz, 15 amp power supply and must also
be electrically grounded in accordance with local codes or, in the
absence of local codes, with the National Electrical Code, ANSI/
NFPA 70 or the Canadian Electrical Code, CSA C22.1.
power fluctuations and electrical noise
The water heater’s control system requires a source of stable
clean electricity for proper operation. Connecting the water heater
to a branch circuit that is subject to fluctuations in voltage level or
electrical line noise such as EMI (electro magnetic interference)
or rFI (radio frequency interference) may cause erratic control
system operation and malfunction.
A high quality power supply filter/suppressor such as the kleen
Line model SELF/T-10 Series SC-L or equivalent must be
installed if the above conditions exist. Call the technical support
phone number listed on the back cover of this manual for more
information.
note:
Malfunctions caused by the power supply and the costs
to install power supply filters are not covered under the limited
warranty.
dedicated power wiring and breakers
Dedicated power supply wires, ground wiring and dedicated
circuit breakers often prevent electrical line noise and should be
considered when installing the water heater.
polarity sensitiVe
The control system on the water heaters covered in this manual
is polarity sensitive; electronic flame sensing requires correct
polarity. The control system is programmed to monitor the
incoming power supply. If the Hot and Neutral wires in the 120
VAC power supply are reversed, the control system will declare
a Fault condition and lock out, heating operation will be disabled
until the power supply is correctly wired. The control system will
display the “AC reversed” Fault message on the LCD.
See Electrical Wiring on page 38 for installation instructions.
table 3
MODEL
*MANIFOLD PrESSurE †MINIMuM SuPPLy PrESSurE ‡MAXIMuM SuPPLy PrESSurE
NATurAL gAS
PRoPANE GAS
NATurAL gAS
PRoPANE GAS
NATurAL gAS
PRoPANE GAS
AJWSH130300 4” W. C. (1.0 kPa) 10” W. C. (2.49 kPa) 5.2” W. C. (1.29 kPa) 11” W. C. (2.74 kPa) 10” W. C. (2.49 kPa) 12” W. C. (2.99 kPa)
AJWSH130400 N/A 10” W. C. (2.49 kPa) 5.2” W. C. (1.29 kPa) 11” W. C. (2.74 kPa) 10” W. C. (2.49 kPa) 12” W. C. (2.99 kPa)
* Manifold gas pressure; reading can only be taken while gas is flowing. reading taken should be ± 0.3” W. C. of the listed value. These water heaters are certified for
use without modification for altitudes up to 10,000 feet. For elevations above 10,000 feet (3,048 meters) see High Altitude Installations on page 51.
† Minimum supply gas pressure; readings are taken while gas is not flowing (static pressure) AND while gas is flowing (dynamic pressure). Supply pressure must never
fall below the minimum values. Supply gas pressures should be measured with all gas fired appliances connected to a common main firing at full capacity. If supply
pressure drops more than 1.5” W. C. as gas begins to flow the supply gas system (gas line/regulator) may be restricted or undersized. See Table 4 and the Supply
gas regulator requirements below. See Supply gas Line Installation on page 36 and Supply gas regulator on page 13 for sizing and installation instructions
also.
‡ Maximum supply gas pressure; reading are taken while gas is not flowing (static pressure) AND while gas is flowing (dynamic pressure). Supply pressure must never
exceed this maximum value.
supply gas line
The high efficiency water heaters covered in this manual require
an adequate volume of fuel gas for proper operation. A lack of
fuel gas volume can lead to ignition failure, rough starting and
rough operation. Increasing the supply gas pressure DoES
NoT
necessarily increase the volume of gas supplied to the
water heater and must remain below the maximum supply gas
pressures shown in Table 3.
The minimum supply gas line sizes shown in Table 4 must be
observed on all installations to help insure an adequate volume
of fuel gas is provided. Do NoT use flexible gas piping.
Supply gas lines serving more than one appliance may require
larger sizes than what is shown in Table 4. See gas Line Sizing
on page 36.
minimum supply gas line siZe
table 4
MODEL *NATurAL gAS
PRoPANE GAS
AJWSH130300
1 1/4” NPT 1 1/4” NPT
AJWSH130400
1 1/4” NPT 1 1/4” NPT
Depending on the installed equivalent length, and/or the number of appliances
connected, the supply gas line size may have to be increased beyond the
minimum required sizes shown in this table - see gas Line Sizing on page 36.
supply gas regulator
The maximum allowable gas supply pressure for this water
heater is 10.0” W. C. (2.49 kPa) for natural gas and 12.0” W.
C. (2.99 kPa) for propane gas. Install a positive lock-up gas
pressure regulator in the gas supply line if inlet gas pressure can
exceed these pressures at any time.
If a positive lock-up regulator is required follow these instructions:
1. Positive lock-up gas pressure regulators must be rated at or
above the input btu/hr rating of the water heater they supply.
2. Positive lock-up gas pressure regulator(s) should be installed
no closer than 3 feet (1 meter) and no farther than 8 feet (2.4
meters) from the water heater’s inlet gas connection.
3. After installing the positive lock-up gas pressure regulator(s)
an initial nominal supply pressure setting of 7.0” W.C. while
the water heater is operating is recommended and will
generally provide good water heater operation. Some addition
adjustment maybe required later to maintain a steady gas
supply pressure.
installation reQuirements
gas pressure reQuirements