Rheem Guardian PowerVent Installation guide

Guardian PowerVent Training Manual SVC900; Rev 1
Page 1
Guardian PowerVent Training Manual
Flammable Vapor Ignition resistant (FVIR) compliant PowerVent water
heater manufactured after 1 January 2006
Table of Contents
INTRODUCTION ............................................................................................................................... 3
SAFETY............................................................................................................................................ 3
COMPONENTS OF AGUARDIAN POWERVENT WATER HEATER .................................................. 5
DEFINITIONS ................................................................................................................................... 9
LOCKOUTS .................................................................................................................................... 10
SEQUENCE OF OPERATIONS ......................................................................................................... 11
TIMING AND SETTINGS ................................................................................................................ 17
DIAGNOSTIC FLASH CODES ......................................................................................................... 17
HOW TO INTERPRET THE FLASH CODES..................................................................................... 18
HOW TO CHECK THE VACUUM SWITCH..................................................................................... 22
HOW TO CHECK THE THERMISTOR (TEMPERATURE SENSOR) ................................................. 22
HOW TO CHECK THE ECO (ENERGY CUT-OFF) ........................................................................ 23
HOW TO CHECK THE GAS CONTROL VALVE.............................................................................. 23
HOW TO CHECK THE VENT OVER TEMPERATURE SAFETY SWITCH......................................... 24
HOW TO CHECK THE IGNITOR.................................................................................................... 24
HOW TO CHECK THE ELECTRONIC GAS CONTROL .................................................................... 25
HOW TO CHECK THE FLAMMABLE VAPOR SENSOR ................................................................... 26
CONNECTION DIAGRAM ............................................................................................................... 26
TROUBLESHOOTING TABLE ......................................................................................................... 28
HOW TO REMOVE THE GUARDIAN POWERVENT INNER ACCESS DOOR.................................... 31
HOW TO REMOVE THE GUARDIAN POWERVENT PILOT IGNITER ASSEMBLY ........................... 33
HOW TO REMOVE THE GUARDIAN POWERVENT GAS CONTROL .............................................. 35
HOW TO REPLACE THE GUARDIAN POWERVENT VENT OVER TEMP SWITCH ......................... 37
HOW TO REPLACE THE GUARDIAN POWERVENT VACUUM SWITCH......................................... 39
HOW TO REPLACE THE GUARDIAN POWERVENT ELECTRONIC CONTROL MODULE ............... 40
HOW TO REPLACE THE GUARDIAN POWERVENT FLAMMABLE VAPOR (FV) SENSOR.............. 42
RESET PROCEDURES FOR INVENSYS CONTROL .......................................................................... 44
WHITE RODGERS GAS VALVE ..................................................................................................... 45
RESET PROCEDURES FOR WHITE RODGERS CONTROL.............................................................. 52
Index of Tables
Table 1 – Time and Temperature to Produce a Scald..................................................................... 3
Table 2 – Sequence of Operations ................................................................................................ 16
Table 3 – Timings and Settings .................................................................................................... 17
Table 4 – Diagnostic Flash Codes ................................................................................................ 18
Table 5 – FV Sensor Values ......................................................................................................... 26

Guardian PowerVent Training Manual SVC900; Rev 1
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Table 6 – Venting the Guardian PowerVent................................................................................. 27
Table 7 – Guardian PowerVent Troubleshooting Table............................................................... 30
Index of Figures
Figure 1 – Components of Guardian PowerVent Burner Assembly............................................... 7
Figure 2 – Components of a Guardian PowerVent Water Heater .................................................. 8
Figure 3 – Wiring Harness Connection Diagram ......................................................................... 10
Figure 4 – Flash Code LED .......................................................................................................... 17
Figure 5 – Blower Motor .............................................................................................................. 21
Figure 6 – Vacuum Switch ........................................................................................................... 22
Figure 7 – Thermistor and ECO Check ........................................................................................ 23
Figure 8 – FV Wiper Gas Control................................................................................................. 23
Figure 9 – Vent Over Temperature Safety Switch........................................................................ 24
Figure 10 – Ignitor Assembly ....................................................................................................... 25
Figure 11 – Gas Valve Connections ............................................................................................. 25
Figure 12 – Flammable Vapor Sensor Check............................................................................... 26
Figure 13 – Connection Diagram.................................................................................................. 26
Figure 14 – Invensys Reset Procedure.......................................................................................... 44
Figure 15 – White Rodgers Control Gas Valve ............................................................................ 45
Figure 16 – White Rodgers Connection Diagram......................................................................... 51
Before inspecting, diagnosing, repairing or operating any water heater, be sure
to examine all of the safety and warning labels on the tank. Follow the
instruction on these warning labels. Read and understand the Use and Care
Manual that was shipped with the water heater. Failure to do so can result in
unsafe operation of the water heater resulting in property damage, bodily injury,
or death. Should you have any problems reading or following the instructions in the Use and
Care Manual, seek the help of a licensed and qualified professional.
NOTICE: This unit is equipped with a Flammable Vapor Sensor. Venting installation of
this flammable vapor ignition resistant water heater involves the use of PVC glue. PVC
glue emits flammable vapors. Do not apply power until enough time has passed to allow the
vapors from the PVC primer and cement to dissipate. Installation in locations with ambient
air over 100 degrees F may lock out the controls.
Copyright 2008, Rheem Manufacturing Company, Water Heater Division.

Guardian PowerVent Training Manual SVC900; Rev 1
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INTRODUCTION
This is a training manual not a job site service manual, nor a parts manual. The intent of this
manual is to train users of PowerVent water heaters. This manual does not assume any particular
user liability, skill level, experience or expertise. The terms and component parts used in this
manual are current manufactured items or vendor provided items used in Rheem PowerVent gas
water heaters, whether natural or liquid petroleum (L.P.). Exercise care when installing and
repairing gas water heaters. Finally, we encourage all users to exercise good common sense and
check your local plumbing, electrical and gas building codes.
SAFETY
FLAMMABLE LIQUIDS AND VAPORS Gasoline, as well as other flammable material and
liquids (adhesives, solvents, etc.), and
vapors they produce are extremely
dangerous. DO NOT handle, use or
store gasoline or other flammable or
combustible materials anywhere near or
in the vicinity of a water heater. The
spark ignition and burner assembly in
the water heater controls can ignite
these vapors. Failure to do so can result
in property damage, bodily injury or
death.
WATER TEMPERATURE ADJUSTMENT
Safety and energy conservation
are factors to be considered when
selecting the water temperature
setting on the thermostat. Water
temperatures above 1250F can
cause severe burns or death from
scalding. The chart shown here
may be used as a guide in
determining the proper water
temperature for your home.
Table 1 – Time and Temperature to Produce a Scald

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There is a hot water scalding potential if the thermostat is set too high. The temperature of the
water in the heater is regulated by the adjustable thermostat located
inside the control enclosure.
Be sure to read and follow the warnings outlined on the warning
label. This label is located on the water heater.
To comply with safety regulations the thermostat was set at 680F
before the water heater was shipped from the factory. Households
with small children, disabled, or elderly persons may require a
1200F or lower thermostat setting to prevent contact with HOT
water and potential scalding.
ELECTRICAL SHOCK - Troubleshooting and repairing a PowerVent water heater can expose
you to electrical shock. Some of the diagnostic procedures require the presence of 120 volt AC
electricity. Use extreme caution when performing these procedures. When replacing an
unserviceable component, turn off all power to the water heater and check for the presence of
power with a multimeter or test lamp. The pilot electrode and ignition cable carry more than
10,000 volts of electrical energy. Use extreme caution when diagnosing the PowerVent.
AUXILIARY CATCH PANS - The water heater should not be located in an area where leakage
of the tank or connections will result in damage to the area adjacent to it or to lower floors of the
structure. When such areas cannot be avoided, it is recommended that a suitable catch pan,
adequately drained, be installed under the water heater. The pan must not restrict combustion air
flow around the bottom of the heater. Auxiliary catch pans must conform to local codes.
18 INCH WATER HEATER STANDS
Because of natural air movement in a room or other enclosed space, flammable vapors can be
carried some distance from where liquids which give off flammable vapors are to be used or
stored. The open flame of the water heater’s pilot or main burner can ignite these vapors and
create a shut down condition of the water heater which will not allow the water heater to ignite
until examined by a Qualified Service Technician. If local codes require the use of a stand kit to

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raise the water heater 18” above the floor, please contact the store where the water heater was
purchased, or any water heater distributor. These kits must comply with local codes.
The 2002 National Fuel Gas Code reads as follows:
8.1.10 Installation in residential garages
8.1.10.1 Gas utilization equipment in residential garages and in adjacent spaces that open
to the garage and are not part of the living space of a dwelling unit shall be installed so
that all burners and burner ignition devices are located not less than 18 in. (460mm)
above the floor unless listed as flammable vapor ignition resistant.
The 2003 International Fuel Gas Code has also been changed to reflect the exception:
305.3 Elevation of Ignition Source:
Exception: Elevation of ignition sources are not required for appliances that are listed as
flammable vapor resistant and for installation without elevation.
Residential Guardian PowerVent Certification Standards
The Guardian PowerVent meets the following manufacturing, certification, energy efficiency
and Low NOx standards:
•ANSI Z21.10.1-2004 – manufacturing and flammable vapor resistance standard
•CSA 4.1a-2000 – Certification standard for North America
•National Appliance Energy Conservation Act – Energy efficiency standard
•South Coast Air Quality Management District – Low NOx emissions standard
COMPONENTS OF AGUARDIAN POWERVENT WATER HEATER
Anode Rod – Rod made of a magnesium alloy that aids in the cathodic protection of the inner
tank through the control of electrolysis. An anode rod can be made of any material that is more
negative than the steel of the tank.
Anti-Siphon Hole – A small hole located in the dip tube approximately six inches from the top.
The anti-siphon hole is designed to prevent the siphoning of water through the cold water line in
the event of a loss of water.
Blower Motor Assembly – Electric motor that mechanically induces the proper draft for venting
combustible gases. Also actuates the vacuum safety switch.
Burner Assembly – Metal fluted burner plate, igniter, pilot supply tube, main burner supply
tube and door with gasket that disperses the main gas supply for ignition. The burner assembly
provides the flame and heat to the water heater. There is a different burner assembly for propane
gas and natural gas.
Burner Access Door – Metal door with burner assembly attached. Provides pathway for igniter
wire, pilot and main supply gas tube and sight glass window. Connects to combustion chamber
with Torx #20screws.
Burner Door Access Gasket – Gasket used to seal the inner door to the combustion chamber to
prevent the escape of flammable vapors.
Burner Supply Tube – Supply tube that carries the most gas to the burner plate.

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Cold Water Inlet – Supply pipe that delivers cold water from the main supply to the water
heater.
Combustion Air Inlet Openings – Air pathway on the outer jacket with small holes. The holes
are designed to trap lint, dust and oil that would naturally accumulate inside the combustion
chamber. Aids in a cleaner main burner flame pattern.
Dip Tube – Non-metallic tube extending from the cold water inlet to a predetermined area of the
tank near the bottom of the tank that feeds water into the system. The length of the dip tube will
vary from product to product.
Drain Valve – Valve used to drain the hot water when performing periodic cleaning or replacing
a part.
Flue – Device that carries the combustion air from the combustion chamber and discharges it the
venting.
Flue Baffle – Device that retards air movement through the flue. Keeps the heated combustion
gases in the flue longer for maximum heat dispersion to the tank water.
Flame Arrestor Plate - Perforated metal plate inside the combustion chamber. If a flammable
vapor event occurs, this plate allows the vapors to burn (much like a candle) on the surface of the
plate. This prevents the ignition of flammable vapors outside the water heater.
Floor Shield – Metal plate between the arrestor plate and the tank bottom of the water heater.
This plate protects the flame arrestor from falling debris and prevents it from accumulating on
the arrestor plate.
Foam Insulation – Insulation between the steel tank and the outer jacket that helps prevent heat
loss to the ambient atmosphere.
Flammable Vapor Sensor – The sensor located just below the outer door to the combustion
chamber that continuously monitors for the presence of flammable vapors. This is a one time use
sensor.
Gas Control Valve – Integrated electronic control module and gas valve that takes the
unregulated main supply gas and regulates the gas for use by the water heater. Also contains the
electronic control module for the operation of the product. The control is responsive to flame
properties, sensing the presence or absence of flame, and in the event of ignition failure or unin-
tentional flame or flame extinguishments, forces the safety shutdown. The gas control valve also
contains the thermostat that controls the temperature of the water, the high limit safety switch
and the flammable vapor sensor controls.
High Limit (ECO) Switch – (Energy Cut Off) - Safety device located on the thermostat that
shunts all power to the control module if the temperature of the water in the tank becomes
excessive. The ECO will trip off at approximately 200 degrees Fahrenheit.
Hot Water Outlet – Supply pipe that delivers the hot water to the faucets.
Inner Tank – Steel tank with a porcelain enamel (glass) lining that stores the hot water.
Outer Jacket – Thin metal outer shell of the water heater.
Pilot / Igniter Assembly – The sparking device designed to ignite the pilot and main burner
when the thermostat demands heat. Sometimes referred to as the spark ignitor.
Pilot Supply Tube – Supply tube that carries the pilot gas to the pilot hood and ignitor.
Sight Glass – Glass window on the inner door allowing visual inspection of the combustion
chamber.
Shut off Plate – Combustion air inlet plate located on the bottom of the combustion chamber. It
allows combustion air into the chamber. When the thermal release device trips, this plate will
close and suffocate any flames inside the combustion chamber.

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Thermal Release Device – (TRD) Mechanism that detects and trips in the presence of high heat
inside the combustion chamber. This higher than normal heat could mean a flammable vapor
incident or the creation of carbon monoxide.
Temperature and Pressure Relief Valve – Safety device that vents extreme pressure and
exceedingly hot water outside the tank to prevent tank rupture and explosion. Commonly called
the T&P valve, it is designed to operate at approximately 150 PSI or 2100F.
Vacuum Switch – Safety device that will allow power to the gas control module. Senses the
presence of vacuum from the blower motor to verify proper venting before it opens the gas
valve.
Figure 1 – Components of
Guardian PowerVent
Burner Assembly
Propane Natural

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Figure 2 – Components of a Guardian PowerVent Water Heater

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DEFINITIONS
•Automatic Restart Time - The period of time between a lockout and the automatic action
to initiate another ignition period. (60 minutes)
•Flame-Establishing Period - The period of time between initialization of gas flow and
proof of the supervised flame. (also called flame rectification)
•Flame Failure Response time - The period of time between loss of the supervised flame
and the action to shut off the gas supply. (The time it takes for the flame rectification
circuit to realize there is no flame and the control module shutting off the gas valve.)
•Ignition Attempts - Number of attempts in a single call for heat to ignite the gas before
locking out. The number of attempts will be zeroed if there is proof of flame for more
than 10 seconds. (3 ignition attempts)
•Ignition Activation Period - The period of time between energizing the gas valve and
deactivation of the ignition source during a trial for ignition period.
•Ignition Recycles - Number of attempts in a single call for heat to initiate gas flow if
proof of flame has been established and is then lost. (3 ignition attempts)
•Lockout - The automatic action to end an ignition sequence. Reinitiating another ignition
sequence may require a manual operation (reset).
•Pilot Flame Establishing Period - The period if time between initiation of pilot gas flow
and proof of the supervised pilot flame.
•Purge time - The period of time intended to allow for the dissipation of any unburned gas
or residual products of combustion.
oPre-purge Time - The purge time which occurs at the beginning of heat cycle
prior to initiating ignition.
oInter-purge Time - The purge time that takes place between the end of trial for
ignition period and reactivation of the ignition source on the multi-try system.
oPost-purge Time - The purge time which occurs at the end of a heat cycle.
•Recycle Time - The period to time between shut-off of the gas supply following loss of
the supervised ignition source or the supervised main burner flame and the reactivation of
the ignition source.
•Set Point - A selectable temperature set by the user. Temperature selection is made by
rotating the red knob on the face of the gas control valve.
•Temperature Differential - The temperature difference between when the thermostat is
satisfied and a call for heat. Usually expressed in +/- from temperature setting.
•Trial for Ignition Period - The period of time between energizing and de-energizing the
gas valve, if proof of supervised flame is not established.
•Valve Sequence Period - The sum of all trial for ignition periods prior to lockout, if proof
of the supervised flame is not established.

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LOCKOUTS
Internal Lockout - As the control performs its various control checks of the microprocessor’s
function and feedback circuitry it detects a fault condition. The control will respond by de-
energizing all outputs and entering a lockout. The control will lockout if a failure is detected
within the control or it recognizes flame when none should be present. The LED will be turned
Steady On and all other inputs will be turned off. The control must be manually reset by cycling
the line voltage.
External Lockout - The control will lockout if it failed to ignite gas after the specified number of
ignition attempts (3) or detected improper states of safety switch (ECO or vent over temp
switch). The green led will flash a code to indicate the type of failure. (See LED chart). The
blower motor will be turned on if flame is detected and all other outputs will be turned off. The
control must be manually reset by cycling the line voltage.
LFL Lockout (Lower Flammability Limit)
The control shall lockout if it senses the LFL
Fault signals from the sensor. The control shall
respond to LFL fault in the following manner:
•The main valve, pilot valve and spark
igniter shall be de-activated.
•The LED error code for the “Flammable
Vapor present” Condition shall be
displayed.
•The inducer blower shall be energized
for the Post-purge time at the beginning
of lockout.
•The control shall remain in lockout until
external LFL Lockout Reset is resolved.
Once the control detects Lower Flame Limit
(LFL) Fault signal, the control will de-energize
main valve, pilot valve and spark igniter, and
enter the LFL lockout. The inducer blower
shall be energized for the Post-purge time of 30
seconds at the beginning of lockout. The
control shall output the corresponding error
code to diagnostic LED.
If the LFL senses a miswired condition, such as
a shunt or plug, the control shall output the
corresponding code to diagnostic LED.
Figure 3 – Wiring Harness Connection Diagram

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SEQUENCE OF OPERATIONS
All voltage inputs are 120V. Neither a surge protector nor GFI circuit is recommended or
required. All electrical connectors are Molex and fit one way. The word ‘control’ in this
sequence will normally refer to the electronic control module on the gas valve. The control
constantly monitors the water temperature via the thermistor so that the water temperature is
within the user-selected temperature range. Control monitors the inputs for any fault conditions
and presence of flammable vapors. If “Call for Heat” has not initiated for more then 6 hours, the
control will automatically decrease the differential by 5°F. If the temperature is still not less than
the set temperature minus differential, the control continues in Stand-by mode.
Tank is cold and full of
water.
Gas supply is connected.
Gas valve is set to ON
position.
Unit is plugged into a 3-
prong plug. Unit is polarity
sensitive.
Fill tank.
Connect gas.
Turn valve ON.
Must be plugged
into a 3-prong
wall socket. Socket must be
wired polarity correct. Black
wire to brass screw; white
wire to silver screw.
Turn temperature dial down
to LOWEST position.
Turn rocker switch to ON
position.
Rocker switch controls all
power inputs to blower
motor, gas valve, and control
module in gas valve. You
will always have 120V at the
red #3 wire.
At power ON and a demand
for heat, the control performs
a self-test diagnostic routine.
If the self-check fails, the
control locks out with a solid
ON LED light.

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Turn temperature dial to
temperature selection.
Initiates a “call for heat”.
120V power is passed from
the red #3 wire – thru the
control – to the yellow #5
wire and to the blower
motor. This is the only
source of AC power for the
blower motor.
The white triangle next to
WARM is the 120-degree
setting.
Temperature is sensed
electronically by the
Thermistor in the sensing
bulb. It is the two white
wires at the RED Molex
connector.
(See Fig 3 on page 10.)
(1st Safety)
Control checks for OPEN
vacuum switch.
You will have 120V at the
blue #8-vacuum switch
wire.
Note: The over-temp switch
in the blower is wired in
series. If the vent temp
exceeds 1800F, then the
over-temp switch will
activate. LED will flash 3/3.
In normal operation, the
switch is OPEN at beginning
of call for heat. If no blower
motor, then check:
120V power at the #5 yellow
wire
Vacuum switch tubing
Vacuum switch
Vent over-temperature
switch is not activated
If vacuum switch has failed
in the closed position, the
control attempts to open the
switch by cycling (turning
off blower, then on) the
blower motor. After 5 cycles
(attempts), the control will
lockout. LED code is 3/1.

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(2nd Safety)
Control turns on blower
motor. This creates enough
venting to close the vacuum
safety switch.
Blower is in pre-purge stage
for about 15 seconds.
You will have 120V at the
yellow (#5-blower motor)
wire. If you hear spark, then
there is 120V power at the
yellow #5 location.
In normal operation, the
control checks for a closed
vacuum switch within 12
seconds before starting the
pre-purge time. The vacuum
switch measures the vacuum
created by the blower and
verifies the blower is
operating at speed. The
control attempts to close the
switch by cycling (turning
off blower, then on) the
blower motor. After 5 cycles
(attempts), the control will
lockout. LED flashed 3/3.
Ignition attempt
Spark ignitor begins to
spark. (Orange wire)
120V voltage opens pilot
vein of gas valve.
You will have 120V at the
yellow #7 pilot valve wire.
Listen for spark ignitor.
Visually verify spark at the
pilot electrode.
Check to make sure the
valve is turned ON.
Check for voltage to the pilot
valve yellow #7 wire
connection.
Visually verify pilot flame is
present.
(3rd Safety)
Flame is rectified.
Pilot lights.
After pilot flame has been
recognized (rectified), the
spark will stop
Main valve is energized.
Note: There is always a
flame rectification circuit
check while the main burner
is operating. When the main
burner fails, the unit will
recycle and attempt ignition.

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Main valve on gas valve
opens.
You will have 120V at the
blue #6 main valve wire.
The “trial for ignition” will
last for 75 seconds. If the
control is not able to
establish a pilot flame, it will
initiate the inter-purge. This
is a 30 second purge without
spark or gas to clear the
combustion chamber. Then
the unit will retry for
ignition. The unit will try 3
times total for ignition. If
ignition fails, it will initiate a
post-purge (30 seconds) to
clear the combustion
chamber; then go into
lockout. LED flashes 1/1.
Main burner ignition.
The flame rectification
circuit is constantly “ON”
during pilot and main
burner. If the control
module thinks flame is
suppose to be present, then
the circuit constantly
‘looks’ for the presence of
flame.
Check for 120V power to the
main valve (blue wire) side
of the gas valve.
If the unit rectifies flame for
at least 10 seconds, the
internal counter resets to
zero.
If the flame is established
and then lost, the control will
turn off the main and pilot
valve, execute an inter-purge
(30 seconds) and then start a
new trial for ignition
sequence.
Water heats to thermostat
setting.
(4th Safety)
Blower motor thermal
safety switch is monitoring
venting temperatures.
Flammable Vapor (FV)
sensor is monitoring.
ECO is monitoring water
temperature.
Blower motor thermal safety
switch set to 180°F with
automatic reset.
FV Sensor is monitoring
local environment for
presence of flammable
vapors

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Page 15
Water is heated. Thermostat
and control module shuts
off all power to the unit.
Unit is in stand-by mode.
(The electronic control
checks to see if the water
temp is close to the set
point. If so, it will attempt
to turn the main burner on.
For instance, if the set point
is 1200, then after 6 hours,
the control module will
adjust the set point back to
1150to see if it can fire off
the main burner.)
In stand-by mode, the
control module constantly
monitors the water
temperature via the
thermistor to ensure the
water inside the tank is
within the user-selected
range.
In addition, the control will
monitor the inputs to look
for any other fault conditions
such as a control health,
false flame or faulty
switches.
Unit is in Stand-by mode Unit monitors control health
and the local environment
for flammable vapors as long
as there is 120 VAC to the
water heater.
False sensing
The blower will turn on
immediately if flame is
sensed when no flame
should be present.
Flame with gas valve off -
If there is proof of flame for
10 seconds with the gas
valve off, the control will go
into lockout. The blower
motor will run during
lockout if there is proof of
flame. If there is proof of
flame for less than 10
seconds, the unit will post-
purge. LED flashes 4/3.

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Page 16
ECO High Limit:(>2000F)
The high limit switch opens
after flame is established.
That means the water in the
tank got over 2000F.
The pilot valve, main valve,
and spark ignition are turned
off, but the blower will
remain on. LED flashes 4/2.
The ECO has a one-time use.
Table 2 – Sequence of Operations
N O T E S

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TIMING AND SETTINGS
Unless otherwise noted, all nominal functional timings are to be accurate to ±1 second or 5%,
whichever is greater, over the specified operating temperature and voltage ranges
Timing/ Setting Nominal
Temperature differentials (factory pre-set) 15
Temperature set point range 950- 1580
Flame Establishing Period 2 Seconds
Flame Failure Response Time 2 Seconds
Recycle Time 15 Seconds
Lockout Time 285 + pre-purge time in Seconds
Vacuum switch short cycle 9 Seconds
Vacuum switch long cycle 12 Seconds
Pre-purge time (factory pre-set) 15Seconds
Inter-purge Time 30 Seconds
Post-purge Time (factory pre-set) 30 Seconds
Ignition Activation Period 75 Seconds
Trial for Ignition Period 75 Seconds
Valve Sequence Period 225 Seconds
Automatic Restart Time 60 minutes
Number of ignition trials 3 times / trails
Table 3 – Timings and Settings
DIAGNOSTIC FLASH CODES
Another new feature of the Guardian PowerVent is the LED diagnostics system built into the
control module. When the unit faults, the LED will flash a
certain number of times. A flashing green LED diagnostic code
indicates that a sequence of events has forced a lockout
condition and is in a lockout state. Number of flashes indicates
the type of failure. The flash code or number of flashes will
occur followed by a pause before it repeats. Any power
interruption of more than 2 seconds – with the reapplication of
power, will re-set the controls. If a fault condition existed prior
to the reset, the fault condition will clear with the exception of
the FV sensor codes. If the fault condition still exists after the
application of power, the control will indicate the appropriate
fault.
Figure 4 – Flash Code LED
A green LED is provided to indicate system status.
When a fault occurs within the water heater, the control will output a code using an LED.

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The LED will have a variety of status conditions:
•ON is defined as constantly on with no blinking patterns.
•Slow Blink is defined as a one blink per second.
•Fast blink is defined as five blinks per second.
•There will be a 1 second period between primary and secondary pattern when LED will
be off. (blink-one second-blink)
•After the secondary pattern completes, there will be a 3 second period when LED will be
off before patterns repeat. (blink-one second-blink - - three seconds - - blink-one second-
blink)
System condition Primary pattern Secondary pattern
Stand-by mode Slow blink None
Call for heat present Fast blink None
Internal control failure/ miswiring ON Solid None
Ignition failure 1 blink 1 blink
Flammable vapors present 2 blinks 1 blink
Flammable Vapor Detector failure/ miswiring 2 blinks 3 blinks
Vacuum switch fails to open 3 blinks 1 blink
Vacuum switch fails to close 3 blinks 3 blinks
Line/ neutral polarity failure 4 blinks 1 blinks
ECO failure 4 blinks 2 blink
False flame 4 blinks 3 blinks
Vacation mode active 5 blinks None
Table 4 – Diagnostic Flash Codes
HOW TO INTERPRET THE FLASH CODES
Solid ON – If the green LED is constantly on, then there is a problem with the internal controls
(computer chip) of the gas valve. It can also mean the thermistor/ECO is disconnected. Ensure
all connections to the valve are tight and correct. Cycle the power to attempt to reset the control.
Slow Flash - Flashing LED indicates normal operation of the controls. This also indicates the
unit is in Stand-By mode and the water inside the tank is hot. There is always a slow flash when
power is applied. If there is no LED, then check for unit plugged in. Check for power at the wall
plug or other source of 120VAC. Verify 120VAC power at the red #4 wire.
Fast Flash – A fast flash indicates there is a call for heat. You should hear the blower motor
running at a minimum.
One (1) Flash / One (1) Flash – Ignition Failure. This means there was no flame rectification of
the pilot. Maximum ignition attempts made. This failure occurs when the control does not see
proper ignition (flame rectification) given the allotted attempts and ignition cycles. (3)
Remember, flame rectification is required before the unit will continue and open the main valve
of the gas valve. The flame rectification circuit proves the presence of pilot flame at the pilot and

Guardian PowerVent Training Manual SVC900; Rev 1
Page 19
ignitor. The control will lockout if it failed to ignite gas after three (3) ignition attempts. Here is
how it works:
1. Verify control valve is ON.
2. Verify there is gas to the valve.
3. Verify minimum gas pressure.
4. Check for 120V voltage to the pilot valve (yellow wire) connection at the gas valve. If
voltage is present, replace control valve.
5. If voltage is not present then check for 120V at terminal #7 (yellow wire) and at #5
(yellow wire). If power at #5, but not at #7, then replace control.
6. If power at #7, check yellow wire and Molex connector to valve. Listen for the spark
ignitor. If you do not hear spark, verify 120V at the red #4 wire on the control. Replace
the control module.
7. If you hear spark, using insulated pliers, remove the orange cable from the control and
reset heater. When you hear spark again, slowly move the orange wire terminal back to
the control and verify spark with at least 1/8 inch gap. If there is no spark, replace the
control.
8. If there is spark, but not at the ignitor, the check for proper spark gap between electrode
and pilot hood. Replace ignitor.
9. If there is spark, then check for a pilot flame first. If there is no pilot flame, then check
power to the pilot side (yellow wire) of the gas valve.
10. Check for gas and gas pressure.
Two (2) Flash / One (1) Flash – The FV sensor has detected a flammable vapor. There is no
recovery from this fault code. The electronic control module and sensor must be replaced.
Two (2) Flashes / Three (3) Flashes – The FV sensor has malfunctioned is miswired. There is
no recovery from this fault code. The electronic control module and sensor must be replaced.
Three (3) Flashes / One (1) Flash – The vacuum switch has failed to open. The control insures
that the vacuum switch is open before it turns on the blower. If the control cannot force the
switch to open by cycling the blower, it will indicate this failure. The vacuum switch is a safety
device. Vacuum switch is normally open. The control checks to ensure the vacuum switch can
open (safety position) before it starts its sequence. If the switch is closed and cannot be opened,
the code will flash. Vacuum switch is closed and cannot be opened.
1. Turn heater off and remove wires to vacuum switch.
2. Measure continuity thru the switch.
3. If there is continuity, then replace switch.
Three (3) Flashes / Three (3) Flashes - Vacuum switch fails to close. When the blower is
turned on, the control insures it that the vacuum switch is closed before continuing with the
ignition sequence. If it cannot force the switch to close by cycling the blower, it will indicate this
failure. The vacuum switch may also fail or fault during main burner. If this happens, then you
will get a flash code of four. If blower motor is operating at speed and there are no vacuum
restrictions, a closed vacuum switch will allow 120V power to pass between the red (inbound)
wire and the blue (outbound) wire. Blocked venting will be a primary cause of this failure. If