John Wood Commercial - 300-400K BTU - Manual (Page 56)

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• Excessive manifold gas pressure - see Table 3 on page
13 and Manifold gas Pressure Adjustment on page 50.
• Vent (exhaust) gas recirculation at the vent and intake air
pipe terminations on Direct Vent installations - see Direct
Vent Installation on page 22.
• Excessive equivalent lengths of intake air and/or vent
(exhaust) piping installed - see Venting requirements on
page 21.
• Debris clogging/blocking the intake air screen(s) - see
Figure 17 on page 23 and Figure 22 on page 25.
• Debris clogging/blocking the Main burner - see Figure 2 on
page 7.
momentary ignition
Burn Hazard
Do not reach into the burner housing or
combustion chamber if the water heater
is still hot.
•
Allow the water heater to cool and always use
gloves when handling the main burner.
•
•
The combustion chamber and burner sleeve
and housing become very hot during operation.
CAUTION
If the Main burner ignites momentarily but does not sustain
ignition allow the water heater to try to ignite up to two more
times until control system locks out and the Ignition Failure Fault
message is displayed on the control system's LCD. If the water
heater is experiencing rough starts - see rough Starting, rough
Operation on this page. For momentary ignition problems without
rough starting check the following:
• Incorrect manifold gas pressure - see Table 3 on page 13
and Manifold gas Pressure Adjustment on page 50.
• undersized supply gas line (low volume of supply gas) - see
Supply gas Line on page 13.
• Supply gas regulator is not installed per installation
requirements (erratic gas supply volume/pressures) - see
Supply gas regulator on page 13.
• See the list of possible causes and things to check and
repair for the Ignition Failure Fault message on page 58.
• Debris clogging/blocking the intake air screen(s) - see
Figure 17 on page 23 and Figure 22 on page 25.
• Debris clogging/blocking the Main burner - see Figure 2 on
page 7.
not enough or no hot water
• No power to the water heater, check breaker, fuses and the
water heater on/off switch.
• Hot water supply valve(s) to fixtures closed.
• Operating Set Point is set too low, Differential setting is set
too high. See Control System Operation on page 41.
• upper and/or Lower Probe Offset settings are causing the
heating cycles to terminate prematurely - see Temperatures
Menu (cont) on page 45.
• Ensure there is not any external supervisory control (using
the enable/disable circuit) disabling heating operation. See
Enable/Disable Circuit on page 38.
• The heating capacity of the water heater has been
exceeded, the water heater is unable to meet demand.
operational problems
Read and understand this instruction
manual and the safety messages
herein before installing, operating or
servicing this water heater.
Failure to follow these instructions and
safety messages could result in death
or serious injury.
This manual must remain with the
water heater.
This section of the manual is intended to be an aid in correcting
common operational problems, it is not all inclusive. The installer
may be able to observe and correct certain problems which
might arise when the water heater is first put into operation or
when it is re-fired after a prolonged shutdown. However, only
qualified service agents, as defined in Qualifications on page
6, using appropriate test equipment, should perform any
service procedures on the water heater.
note:
Call the technical support phone number listed on the
back cover of this manual for further technical assistance or to
locate a qualified service agent in your area.
installation errors
Operational problems on new installations are often the result of
installation requirements that have been overlooked rather than
failed components. IE: A "Low gas Pressure" Fault condition
is most often caused by low supply gas pressure rather than a
defective Low gas Pressure switch. rough starting and rough
operation are often caused by undersized supply gas lines and/
or the absence of a supply gas regulator at the water heater.
Prior to performing any operational checks inspect the water
heater installation to ensure all installation requirements and
instructions have been maintained and followed. See the
Installation Checklist on page 54
note:
Costs to correct installation errors are not covered under
the limited warranty.
rough starting, rough operation
Fire and Explosion Hazard
Turn off gas lines during installation.
Contact a qualified installer or service
agency for installation and service.
Excessive gas pressure to gas valve can
cause serious injury or death.
Do not use water heater with any gas
other than the gas shown on the rating
label.
• undersized supply gas line (low volume of supply gas) - see
Supply gas Line on page 13.
• Supply gas regulator is not installed per installation
requirements (erratic gas supply volume/pressures) - see
Supply gas regulator on page 13.
• Excessive supply gas pressure - see Table 3 on page 13
and Supply gas Pressure Adjustment on page 50.