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Power vent water heater troubleshoot
Troubleshoot power vent water heater

Does not include troubleshoot for condensing type heaters
Basic power vent maintenance/ pdf
burner assemblypower vent water heaterTwo types of power vent water heaters
Vent illustrations pdf
Power vent water heater has one 2-3-4" vent pipe connected to water heater, and derives all incoming air from inside the home and releases combustion gas in the sealed vent installed either horizontally through a side wall, or vertically through roof.
Power direct vent
has two 2-3-4" pipes connected to water heater, one for intake and one for vent. Power direct vent derives all incoming air from outside the home through a sealed intake pipe and is vented through roof or side wall, with outside air supply coming from roof or side wall.

How power vent water heaters works
-The water heater must be plugged into and receiving 120 volts, range 115-125 volt, from a circuit without GFCI protection. Direct-plug only, no extension cords. The outlet can be surge protected using surge outlet or whole house surge protector, but not using a surge module or surge strip that will not provide reliable electrical connection. The outlet must have correct polarity and grounding. Lack of ground will cause flame sensor failure and other problems. Extension cords, incorrect voltage, low voltage, reversed polarity and GFCI cause various issues including short-cycling or continuous blower operation, or insufficient blower rotation. The 120 volt line powers the gas valve, blower and ignition.

-The gas valve controls the operation of heater, and issues error codes when operation encounters problem.
-The gas valve has a metal or metal-tipped probe on backside of valve that extends into the water. On mechanical gas valves, the thermostat probe contains 1) ECO energy cut off that trips when water inside tank reaches 188-199° depending of model of gas valve and 2) a thermistor. The thermistor is a heat sensitive variable resistor. A change in water temperature changes the thermistor resistance (measured in ohms). Newer electronic Honeywell and Intellivent gas valves simply have the thermister that connects to gas valve circuit board, and the change in resistance triggers energy cut off if the board malfunctions or actual temperatures inside tank exceed gas valve high limit. The TP valve should release water at 210° (the highest allowable temp for any water heater). TP valve code
-The gas control valve interprets change in resistance from thermister as a change in temperature and uses information to activate and deactivate call for heat. Water temperature around the thermostat probe can drop 15-25° before heat cycle begins. If water temps inside tank vary to widely or become erratic, the gas valve is out of calibration and needs to be replaced.

-When the heat cycle begins, the Honeywell and Intellivent electronic gas control valves run diagnostic checks to confirm exhaust and intake and ECO contacts are closed (ON), then starts the 120 volt blower prepurge cycle. The blower can run up to 30 seconds before ignition during the pre-purge cycle.
-The blower pulls air up from the combustion chamber into vent pipe and begins a cycle of releasing toxic combustion by-products, including NOx SO CO CO2 and acidic water vapor, into the atmosphere, where it creates an exciting new future for the planet. Alternative for some: Connect solar panels to electric water heater

-The vacuum safety switch (commonly called pressure switch, vacuum switch, air switch) is connected to blower via rubber tube. The rush of air through the vent pipe creates vacuum pressure. 'The vacuum switch is sensitive, so you can blow or suck a little on the tube and that will activate the switch.' 'If the vent pipe has blockage, then back pressure will prevent switch from closing.
-The vacuum switch closes a circuit that tells gas control valve that blower is operating at speed, and it is safe to activate burner. This ensures the blower can evacuate combustion gasses and support complete burning of fuel. Complete burning is essential to prevent explosion hazard caused by ignitable fuel gathering inside combustion chamber or vent pipe.
The efficiency of ordinary power vent water heater combustion is typically 59-61% (when new), with the remaining 39-41% of heat going up the flue pipe or lost in standby. The wasted heat going up vent pipe cannot be recaptured without risk of slowing proper venting on ordianry power vented heaters, causing lockout followed by re-trys before shutting down and issuing error code.
For higher efficiency, buy more expensive condensing heater with higher technology for recapturing heat ... except cost of heater and required maintenance of condensing heater will generally cost more overall, unless home has need for larger output of hot water. Review Polaris condensing heater

-Once the pressure switch indicates that blower is working, the gas valve's electronic control board will activate the hot surface igniter.
-The igniter is consumable and wears out ... If the igniter is not worn out, the wire connections are solid and undamaged, the igniter is not coated with carbon deposits (clean with emery cloth), and tests between 15.5 and 18.8 ohms, then the igniter will glow red with heat while gas is released down the burner tube (also called manifold tube), through the orifice and into the burner head. The igniter can be inspected through the viewport.

-If the gas pressure is good (if gas pressure is suspect, then observe operation of gas appliances when several are turned on at same time), and the orifice is clean and correctly sized, and hot surface igniter and burner head are clean (not sooted with black soot that indicates need for immediate service, including vent and air intake inspection, gas pressure check, incorrect orifice, gas leak at gas control, loose connection between manifold and burner and general combustion chamber cleaning) and burner is in good working order (reasonably quiet during combustion), and the igniter is correct distance away and positioned directly in front of a gas jet, then the gas will ignite (should ignite quickly) and gas will burn blue color with flicks of yellow and red as seen through the viewport (slow ignition, lazy yellow flame, noisy flame, or flame that lifts excessively off burner head indicate need for immediate service).
-When gas is ignited, if the flame sensor is correctly positioned, and not dirty (If  the flame sensor's metal is off color then change it out, or lightly clean with an abrasive cloth), then flame sensor confirms that flame is present and signals the gas valve to continue releasing gas.

-If  the flow of combustion and ventilation air is not blocked, and if there is adequate incoming air supply with enough oxygen to support combustion ... high elevation and high ambient air temps cause air molecules farther apart - thin air can starve gas appliances ... gas burning appliance requires the oxygen contained in 12.5 cubic feet of air (at sea level) for every 1000 BTU of heat generated, ... and if the igniter receives continuous power and glows red continuously during the entire heating cycle, then the burner remains on and water temperature inside tank begins to rise.
-Signs of insufficient air include yellow flame, sooted water heater parts ... and possible smell of burnt gas and carbon monoxide.
-When water temperature inside tank reaches set point, the gas control valve turns off gas to burner. Burner shuts off while blower continues running to evacuate remainder of combustion by-product (called the purge cycle or post purge), then shuts off. If the blower stays on, it is either a stuck pressure switch or bad gas control valve.

-If the water heater has pilot light instead of hot surface igniter, then the gas valve has a pilot tube in addition to the burner tube that connects to burner assembly. The gas valve releases gas into the pilot tube continually as long as thermocouple is functioning and correctly positioned in the pilot flame so it sends small electric current to gas control valve, signaling that pilot flame is on. If the pilot is out, or thermocouple is bad, then the gas valve receives no current, and will not release gas. If the pilot flame and thermocouple are working correctly, the ignition sequence can begin once blower operation is confirmed.

-If the blower is not operating, or running at lower speed because of a brownout or lack of voltage or malfunction, the vacuum switch does not receive enough vacuum pressure and will not close, and the ignition sequence will not take place. Plug blower directly into outlet to check function. Test electric power. Bring power from different outlet. Tap lightly on the switch to see if it closes. Avoid drywall, or construction sanding in same room, and avoid other dusty or dirty conditions that can clog pressure switch. You can NOT jump out (bypass using a wire) the pressure switch because gas valve requires the switch to have open (turned off) condition before the blower gets energized ... This is to prevent folks from bypassing the vacuum switch and causing other problems such as unburned fuel inside a hot vent pipe, creating explosion and fire risk.

-The blower has a built-in, automatic-resetting, thermal safety switch (also called vent over-temperature switch) that monitors temperature of the vent pipe. If temperature on vent pipe at the blower exceeds 160-180°, the thermal switch opens (shuts off) the circuit between gas valve and pressure switch, shutting down the heater. The gas valve thermostat turns off gas supply, blower turns off, the vacuum switch resets to open position. When vent pipe cools to 125°, the heat cycle begins again. Repeated failures in the ignition and heating sequence are recorded by the gas control valve. When errors exceed parameter, the gas control valve issues error code.

-The blower thermal safety switch  is designed to shut off heater if combustion gas reaches 160-180°. This prevents water temperature inside tank from reaching the 188-199° ECO limit of gas control thermostat. If temperature of water inside tank exceeds high limit set point, the ECO trips off, and gas control valve turns off all gas. Older style gas control valve may require replacement. Newer gas control valves can be reset (with exceptions) once repairs have been made to correct cause of overheating. If the thermostat comes out of calibration, and is no longer performing or reading correct temperatures, it requires replacement of gas control valve.

-If the gas valve thermostat is operating correctly and within calibration tolerances, then when temperature inside tank reaches the set point, for example 120°F ±5-10°, the gas control valve turns off gas to burner, and a moment later turns off blower. The water heater goes into standby mode, and the electronic gas control monitors conditions until water temperature drops below thermostat set point again.
Power vent Back to 14 things for troubleshoot gas water heater
12) power vent water heater blower
Blower draws air into combustion chamber and then pushes combustion by-product through the vent pipe where it exits on roof or sidewall of home or structure.
Check blower assembly: Turn off power to water heater. Remove vent from top of blower. Disconnect pressure tube going to pressure switch, and attach a manometer to the pressure tap. Turn on power to the blower. Pressure should be 1.3" w.c. to 1.4" w.c. at normal altitude (3000 ft).

How it works: "When the thermostat senses a need for hot water, the control valve tests for 1) closed blower thermal temp switch, and 2) open pressure switch. If test fails, then gas control locks out and issues error code.
If test is passed, a valve is opened which allows gas to flow to the closed solenoid valve located inside the gas control valve. As gas pressure builds up within the solenoid, the gas pressure switch closes and 24 VAC flows to the blower relay. The blower relay contacts close and send 120 VAC to the blower which turns on. Air flow from the blower closes the air pressure switch sending 24 VAC to the solenoid valve. The solenoid valve opens and allows gas to flow to the burner which is lit by the pilot or igniter"

Blower power consumption: less than 5 amps @ 120 volt. 120 volt x 5 amp = 600 watts running with 1200 watts start-up. 
Buy
Manometer

Resources:
Power vent water heater issues
Anode covered by power vent
How to test gas pressure on gas water heater
How to clean burner
power vent blowerBlower

Blower is connected to gas control valve with a wire (called the control cable).
The gas control uses a firing sequence to activate the blower and start moving air upwards just before the burner fires up.

Blower, control cable, gas control valve, and pressure switch are part of troubleshooting. Eliminate the obvious: Check the blower first, cable next, and gas control valve last.
Make sure blower is aligned on top of heater and the opening is not obstructed by gasket and gasket is not damaged.
Other issues: excessive vent length, vent blockage, high vent temperature, bad wiring inside junction box,

Buy blower:
Water heater blowers at Amazon


Blower troubleshoot
Test pressure switch
Power vent troubleshoot
Troubleshoot power vent hot surface ignition
How to check blower motor
Check blower motor
Example flue pipe chart, gives general rule of thumb for venting a power-vent water heater.

Rely on instruction manual for your specific model for the correct vent installation.
 
water heater blowers Blowers: Fasco, AO Smith, Bradford White, Rheem power vent water heater exhaust draft-induced blowers
Buy blower:

Water heater blowers at Amazon
Other types blowers
Fasco multi-purpose blowers
AO Smith multi-purpose motors and blowers
Furnace blowers
water heater pressure switchTroubleshoot Pressure switch / same as vacuum switch
The vacuum switch measures the vacuum created by the blower and verifies the blower is operating at speed. This ensures the blower can evacuate combustion gasses and support complete burning of fuel so no unburned fuel is inside the vent pipe.
You cannot jumper the the vacuum switch before the heating sequence ... ''At the beginning of a heating cycle the gas control will check if the air pressure switch circuit is open (off) before the control energizes the blower motor. The gas control will check the air pressure switch circuit a second time to insure it is closed (on) after the blower is energized. The gas control monitors circuit during the heating cycle to insure the circuit remains closed. If this circuit opens (even for a split second) ; the control will close the gas valve immediately to insure safe operation.''
You can bypass or jumper around the pressure switch immediately after the inducer starts.
The gas control monitors the pressure switch circuit to make sure the pressure switch contacts are not jumpered before ignition, and that blower is running during heat cycle, and that the vent is not obstructed.

Generally, to check if blower is good and pressure switch is bad, you bypass the pressure switch and connect blower directly to 120 volt outlet, running a pigtail to the blower or plugging blower directly into outlet.
At beginning of a call for heat, the vacuum switch is OPEN. The vacuum switch must close, and complete a circuit that notifies gas control that blower is operating correctly.
Switch can fail to open if there is a vent obstruction or vent is too long. Correct venting.
"In troubleshooting pressure switches, you usually just jumper across it so it looks like a solid wire to the control.  Do this only when the unit is trying to fire up, so it is in the correct sequence. ~~ If you get no continuity however,  then contacts in the switch are shot and the switch should be replaced. Jumpering across it will let you know if that is what's keeping the heater from firing up. Do NOT leave the jumper in place as you're disabling a safety device." Source
"Because one of the two air chambers of vacuum switch is vented to the atmosphere through the vent port, the ambient air pressure is critical. Ambient air pressure can push or pull on the diaphragm through the vent port. If the ambient air pressure is extremely high (positive) or low (negative) it may cause erratic pressure switch operation."

Pressure switches fail when a few drops of water condense in the small tube that connects to the switch, or some other internal problem with contacts happens.  Using a volt meter on the switch while gently blowing /sucking on the tube will confirm it's operation... or lack of operation.

There are different types of pressure switches manufactured for various uses. Power vent pressure switches are all NO normally open (off) with fall in pressure, and close (on) with rise in pressure.
To test: With power off, and wires removed from contacts, test across pressure switch contacts for continuity. Test should show no continuity. If test shows continuity, then replace switch.
Test again while sucking on rubber tube, and pressure switch should show continuity.
Use 3" vent instead of 2" ... long runs of 2” vent may cause the pressure switch to remain closed. 2" pipe causes more back pressure.
Pressure switch troubleshoot
Intellivent pressure switch troubleshoot and testing/ pdf
Test pressure switch
Intellivent wiring
Pressure switch replacement
Bradford White pressure switch replacement
Check pressure switch
Construction, operation, and testing for pressure switch .pdf

The Vacuum line can be clogged
Check pressure switch and vacuum line
"How to check the vacuum line
Requires the use of a magnahelic gauge.
1. Place inline “T” fitting between vacuum switch and vacuum line from the blower motor.
2. Turn heater on and adjust so water heater turns on. Blower motor turns on..
3. Check  pressure on the magnahelic gauge. If gauge shows 0.6 to 1.5 inches water column, then blower motor is inducing the proper draft and vacuum lines are not obstructed.
4. If gauge does not read between 0.6 and 1.5 inches water column -
a. Move the inline “T” fitting and place it between the blower motor and the vacuum tube at the top of the heater.
b. Check the pressure on the magnahelic gauge. If the gauge shows 0.6 and 1.5 inches water column, then the blower motor is inducing the proper draft and vacuum lines are obstructed. Replace the heater.
 c. If the gauge does not read between 0.6 and 1.5 inches water column, then the blower motor is not inducing the proper draft. Replace the blower motor."  Resource: Power vent troubleshoot / pdf
Buy: magnahelic gauge
water heater pressure switch Pressure switch/ Vacuum switch for water heaters
There are 3 major water heater manufacturers, AO Smith, Bradford White, Rheem, that make all the other brands from Kenmore, Craftmaster, Whirlpool, American, Reliant (AO Smith) to Reliance (Rheem)
Buy water heater pressure switch:
Rheem water heater pressure switch
Bradford White pressure switch
AO Smith pressure switch
Outlet polarity120 volt single-phase, Polarity, Ground
Power vent is connected to 120 (115-125) volt outlet. No electricity, no hot water. 5.2 FLA (full load amps) approximate.
Dedicated line recommended to reduce noise and surge on electric wire.
The outlet polarity must be correct, and water heater must be grounded.
Power vent heater is a polarity sensitive appliance and will not operate if the power supply polarity is reversed.
Poor ground can prevent flame. Water heater’s burner must be grounded for flame sensing current to be established and verify ignition.
GFCI circuit can cause short cycling. If outlet is not dedicated or has GFCI, or line has other loads such as florescent lighting, these factors can cause short cycling.
Unplug cord. Test for continuity between ground prong on plug and manifold tube on gas valve.
Test for continuity between ground prong and blower assembly mounting screw.
Connect water heater to different outlet. Test outlet polarity with circuit analyzer
Buy:
Circuit analyzer

Power vent circuitIntellivent gas control circuit
Vent temperature limit switch monitors the flue gas temperature in blower assembly. If temperature exceeds set point, the limit switch opens and turns off circuit that is routed from gas control valve through the limit switch and pressure switch. This signals to gas control valve to shut down gas flow to burner and water heater stops heating water.

Defective vent temperature limit switch; this is a normally closed switch that opens its contacts on a rise in temperature. Turn off power and disconnect wires to the vent temperature switch.

With the switch at room temperature (77 °F), check for continuity between the two wiring terminals on switch with an ohm meter. If switch contacts are open (no continuity) at room, or below 160°F - replace the switch.

power vent flue restrictorAt top of heater is a flue restrictor plate that is located on vent pipe under the power vent assembly. If restrictor is missing or dislodged, the flow of combustion gas will increase causing more hot gas to reach limit switch. If heat exceeds 160°F limit, the limit switch opens and burner shuts down.

Missing flue baffle can create turbulence inside combustion chamber, that can sweep gas away from burner causing ignition failure, and short cycling where water heater turns off for a few moments and then cycles on again several times before shutting down.
Turbulence can also be caused by improper or missing seal around combustion chamber access door

Resources:
Intellivent wiring
Read about replacing rubber seal
"Use 3 inch vent when in doubt. We have not seen any problems with pressure switch failing to open when using 3 inch vent.• Minimize the vent length when using 2 inch vent. It appears the units fail when the total equivalent vent run is close to the maximum distance outlined in use and care manual. Use long sweep 90 degree elbows if you must use 2 inch PVC vent. Those fittings offer less resistance (back pressure) to the gases being discharged.''

Do not mix 2" and 3" vent pipes.
Typical vent table... use product manual
Minimum distance of vent pipe from window   
Larger image with more information
Minimum distance of vent pipe from window
Side-wall vent pipe must be 4 feet away from windows and doors. And 3 feet away from inside corners.


Consult product manual and local codes for specific vent installation.

Power direct-vent clearances
Venting a gas water heater
Conditions where outdoor air supply is needed
Condensation:
''Formation of condensation in the venting system of Power Vented water heaters is dependent upon installation conditions including, but not limited to:
ambient temperature and humidity of installation location;
ambient temperature and humidity of venting space;
vent distance and slope; and product usage.in order to effectively control condensate from adversely affecting the mechanical components of the water heater several methods may be employed:
1. For horizontal installations the vent pipe can be installed with a downward slope (not less than 1/8 inches (3 cm)) and away from the blower.
2. In order to prevent condensate from draining back into the blower (vertical or horizontal runs), an optional condensate kit is available as a service part (Condensate kit, p/n 238-45875-00). A factory supplied exhaust adapter with drain outlet mounts directly to the blower outlet and is secured with two hose clamps, one to the blower and the other to the vent pipe. Tubing is provided to drain any accumulated condensate away from the water heater and to a suitable drain. The kit comes with instructions for installation.''
Water leak?
A. Water at the blower assembly is water vapor that condensed out of combustion products ... caused by a problem in the vent.
B. Condensation  on pipes in humid weather or pipe connections may be leaking.
C. Anode rod fitting may be leaking (anode is located under the Blower Assembly). Replace anode rode
D. Small amounts of water from temperature-pressure relief valve, possibly caused by thermal expansion or high water pressure. Gently lift and then lower release handle.
E. TP valve leaking at the tank fitting, could indicate rusted tank. Re-install with 6+ wraps teflon tape. How to troubleshoot and replace TP valve
F. Water from a drain valve may be due to the valve being slightly opened. Install hose cap.
G. Drain valve leaking at tank, could indicate rusted tank. Re-install with 6+ wraps teflon tape. How to replace drain valve
H. Combustion products contain water vapor that will condense on cooler surfaces. Drop can drip onto the burner or run on the floor. This is common at start-up and when incoming water is cold.
I. Water in the water heater bottom or on the floor can be caused by condensation, loose connections, or TP valve. Inspection all possible water sources.
Leaking water heater
Steve writes about short cycling:
When my power vent is turned on, the Intelli-Vent activates & the burner ignites normally it burns for about 5 min & stops. After a few ignite attempts, the green led and A & B Yellow leds light up. Problem sticker states “max no. of ignites have been reached & system is in blackout.” This has been ongoing for a few weeks.
Is the vent pipe partially blocked... so the exhaust doesn’t vent properly & the burner is turned off?
Any suggestions to fix it?

Answer for error with A and B light / ignition failure or short-cycling
-Unplug heater to reset gas control valve.

-Low gas pressure can cause . 
-Observe operation of other gas appliances when heater is working. Low gas pressure should affect all appliances.
-Water in gas line and clogging can reduce gas pressure at individual appliance including water heater. Use only black pipe or yellow approved flexible gas line. Galvanized pipe will flake off pieces that can enter gas valve. Connect pipes so no joint compound or teflon tape can get into gas line and enter gas control valve. Install 3" sediment trap on gas line.
-Undersized gas line to heater can affect flow of gas. Check installation manual and BTU rating of heater. In some cases a full 3/4" (or 1") gas line should be run within so many feet of heater before reducing to 1/2" (or 3/4)
-Improper size yellow flex line can constrict gas flow. Check back of package to see BTU rating for each diameter of flex and compare with BTU rating of heater. Use black pipe connection directly to heater instead of flex line.

-Low voltage on 120 volt outlet.
-Min 115, max 125.
-Use dedicated outlet with correct polarity with no other inductive loads or interference on the line.

-Hot surface igniter
-Igniter wears out over time. Measure ohms  If multimeter shows 18.8 ohm resistance at room temperature, then replace ignitor
-If igniter or ceramic is cracked or damaged, replace igniter
-If igniter resistance is than less than 15.5. replace igniter
-If resistance is within range, and igniter is not damaged, then gently clean with very fine steel wool or very fine sandpaper. Do not touch. Oil from fingers can cause damage when igniter is hot.

-Misaligned igniter.
-Just as pilot light keep burner going, the igniter must remain hot throughout the heating cycle to ensure gas flame burns continually.
-If igniter is not sitting in the flow of gas, the heater can 'misfire' and start short cycling.
-Igniter must sit directly in front of a gas port on the burner and be correct distance away.

-Improper vent
-Check installation manual to ensure correct size vent. Vent diameter that is too large or small can cause short cycling.
-Do not exceed maximum overall length, horizontal runs, or number of elbows.
-If heater worked before, then vent installation is probably correct. Check for obstruction at vent termination. Inadequate venting would cause gas to burn lazy yellow color instead of crisp blue with flicks of yellow and red.

-Inadequate air supply... use correct size vent shows in the installation manual, check air intake, get more air to unit ... except if short cycling was caused by lack of air, then it would restart pretty quick when air was naturally replenished during shut down ... and flame would be yellow instead of crisp blue when turned on.

Other causes might include following:
-Rubber pressure tube/ vacuum line clogged or kinked.... check tube ... except why would it start running at all?
-Faulty pressure switch.... replace pressure switch
-Loose or dirty wire connections.... pull off and clean.
-Blower motor overheating, getting hot and slowing down ... replace blower motor

-Dirty combustion parts, faulty flame sensor, bad alignment of flame sensor ... clean burner, manifold tube etc.
-Bad or dirty flame sensor. Remember the flame sensor must operate continuously to keep ignition going since the unit does not have pilot light.
-Faulty or failing gas control valve.

-Overheating... the vent temperature reaches 180 degree F,  thermal switch trips off the blower. Put hand near vent to heel approximate temp, or use a thermal heat gun to measure. This indicates faulty intellivent gas control valve thermostat.

Flame sensor
-When gas is ignited ... if the flame sensor is correctly positioned, and not dirty (If  the flame sensor's metal is off color then change it out, or lightly clean with an abrasive cloth), then flame sensor confirms that flame is present and signals the gas valve to continue releasing gas.
Flame sensor for Honeywell power vent
Flame rod sensor
Location of flame sensor and igniter vary by model and brand of water heater.
Sand carbon deposits off igniter.
Avoid touching igniter
Larger image
Hot surface igniter troubleshoot
Hot surface ignition basics
Troubleshoot hot surface ignition
Hot surface igniter troubleshoot
Power vent hot surface ignition

Tip of flame sensor must be directly in front of burner port.
Use a nickel to set 7/64 gap.
Natural gas flame sensor will be bent, while propane will be straight.
Larger image
Intellivent troubleshoot Manual
Power vent surface ignition
Flame sensor for Intellivent power vent

The lower lip or edge of low NOx burner extends out further than standard burner. Flame sensor gap and elevation are measured from lower lip on low NOx burners .... and from top lip on standard burners.
Specifications here are for standard recovery residential power vent and power direct vent 40 and 50 gallon models.
Flame sensor chart
Power vent Venting for power vent models
Read product manual for venting specifications
Use correct size vent that shows in the installation manual. Too large or too small and the power vent can malfunction.
Example power vent manual p17
Minimum vent distance from window
Power vent tables
Power vent troubleshoot
Typical power vent manual
Typical power vent manual2
Typical service manual
Bradford White power vent service manual
Gas venting specs
Conditions where outdoor air supply is needed
Venting multiple heaters
Soot on gas burner
Soot on top of heater also implies danger of improper vent and backdraft.
Improper location of vent on roof, and incorrect clearances, or windy location can stop vent gas from leaving vent pipe. If vent gas cannot escape at top of pipe, it can be entering house at the vent hood. Soot on top of heater is evidence. If pilot goes out, the improper draft can be blowing out pilot light.
Soot on top of heater can be caused by backdraft where vent gasses are being blown back onto water heater because of shared vent pipe with furnace or other gas appliance. Read next section.
Negative inside air pressure, Negative pressure
Backdraft Is your furnace causing water heater to malfunction? Furnace, kitchen-bath bent fans etc can affect vent draft on water heater. Called negative pressure.
Is there evidence of rusting etc on top of heater, next to the draft hood? Is the furnace room particularly cold or wet? This is evidence of backdraft.
Here is a simple, but telling test. When the water heater first fires up, a little heat will spill from the draft hood. It should only spill for a second or two under normal circumstances. So, with the furnace off, turn the temperature on your heater up to cause it to fire up (you might make a mark on the thermostat dial so it can be put back to the same place). Quickly, put the back of your hand to the draft hood to feel any heat spilling out. Count the seconds. Return the heater to normal. Now wait a bit and fire up the furnace. Feel for any spillage at the water heater draft hood with the water heater off. Count seconds. Now fire up the water heater (furnace running) and check for spillage again.
If furnace and water heater both vent into same chimney, the draft might not work properly. Water heater should have dedicated vent. For example the chimney vent pipe is is eight inch, but the two vents (from furnace and water heater) going to it are both four inch. That bigger vent might be oversized and hard to warm properly for good drafting.
If the furnace is power vent, and fan or vent will overpower natural draft. Having the furnace and water heater vents combined will cause problems. Likely the
right fix is to run two, separate three inch vents. Resource: Venting combustion byproduct .... issues: vent in disrepair, other vents in house drawing air
Water on top of heater. Rusted vent pipe. White condensate on pipes.
Inadequate draft, or improperly installed vent pipe can cause condensation inside pipe that will rust and cause white condensate.
Missing roof cap will cause water on top of heater that will rust out the water heater.

Elbows slow venting, can cause backdraft if vent pipe is not large enough, or serves too many gas appliances..
Resources:
Gas venting specs
Direct vent clearances
Conditions where outdoor vent is required
 
Vent Gas Odor
Lack of air supply
  -Clean air intake screen, open window
  Ventilating tight-house/ pdf
Improper vent
  -Read product manual for vent requirement
Downdraft
Poor combustion
  -Clean combustion parts, service unit
CO poisoning
If joints fall apart, or vent is improperly installed, hot gases enter home posing risk of odorless CO poisoning. Symptoms: headache that goes away when outside in fresh air. Unconsciousness.
Remove affected people from home and lay on sides, not on back. Call emergency help.
call plumber. Attach vent pipe sections with 3 screws and then cover joints with aluminum tape.
Buy:

Vent tape
Carbon monoxide detector
Water leak issues
A. Water at the blower assembly is water vapor which has condensed out of the combustion products.  This is caused by a problem in the vent.
B.  Condensation may be seen on pipes in humid weather or pipe connections may be leaking.
C.  The anode rod fitting may be leaking (anode is located under the Blower Assembly).
D.  Small  amounts  of  water  from  temperature-pressure  relief  valve may be due to thermal expansion or high water pressure in your area.
E.  The temperature-pressure relief valve may be leaking at the tank fitting.
F.  Water from a drain valve may be due to the valve being slightly opened.
G.  The drain valve may be leaking at the tank fitting.
H.  Combustion products contain water vapor which can condense on the cooler surfaces of the tank.  Droplets form and drip onto the burner or run on the floor. This is common at the time of start-up after installation and when incoming water is cold.
Water inside bottom of combustion chamber or on the floor may be from condensation & loose connections, or the relief valve. DO NOT replace the water heater until a full inspection of all possible water sources is made and necessary corrective steps taken.

Resources: Power vent troubleshoot/ pdf
Bradford White power vent service manual


Honeywell
WV4460E power vent  gas valve resource

Range Low 90° - very hot 160°
Average bath 110°F, typical water heater temp 120°
ECO limit 199° F, ECO trips, gas valve fails
Average bath 110°F
ECO limit 199° F
TP release water at 210°
Buy
Example Honeywell gas control valve at Amazon
Reliance NG at Amazon
Replacement instructions
How to replace water heater gas valve

Resources flue damper:
Adjust temperature/ error codes flue damper
How to light Honeywell gas valve
Dampered Fury gas troubleshooting codes
Induced draft troubleshoot codes

Resources for power vent
Error codes, maintenance, install, troubleshoot
Error codes
Error codes2
Example power vent install manual
Example power vent install manual
Example power direct vent install manual

Adjust temperature & Error codes
AO Smith service handbook/ hot surface ignition
Bradford White thru wall power vent service/ with pilot and hot surface igniter
Bradford White power-vent service manual 2/ with pilot and hot surface igniter
Bradford power-direct-vent service manual
Condensing thru wall power vent service
Test gas control/ from BW service manual
Sequence of operation/ w electronic control
How to clean burner
Install, maintain troubleshoot w electronic control
Power direct vent parts

Safety
Water heater safety precautions
Water heater precautions/ pdf
Gas-water-heater-Safety-Precautions
Gas valve safety
Thermal expansion
Insulation blanket


White Rodgers intellivent
For power vent models Range Low 80° to Hot 150° Error C flashes at 160°

Buy
Buy Intellivent gas control at Amazon
White Rodgers/ Rheem Intellivent gas control
AO Smith intellivent
AO Smith Intellivent at Amazon
AO Smith White Rodgers at Amazon

Replacement instructions
How to replace water heater gas valve

Resources:
How to light water heater
Typical installation manual
Sample installation manual
Example install manual
Ultra low nox power vent manual
Error codes and adjust temp on Intelli-vent
AO Smith Intellivent troubleshoot and FV test
Troubleshoot Intellivent/ pdf
FVIR intellivent troubleshoot .pdf
Intellivent service manual TC-048 R6
Sequence of operation and service brief
Intellivent wiring
Power direct vent troubleshoot

How to reset intellivent
For resetting controller:
Method A... After the unit has been off for at least a minute, plug it in, turn on switch; within a few seconds, depress both arrow buttons on controller, and hold them until the left light begins to blink.  Release them, and within a few seconds, push those arrow buttons in the following sequence:  L/R/L/L/R/L/R/R.  This should reset the controller.
Method B... after FV event on AO Smith
1. Turn off power to water heater for 10 seconds.
2. Restore power to water heater.
3. Within 10 seconds of restoring power, press the two temperature adjust buttons simultaneously until the left (green) “Vacation” LED begins to blink (approx. 5 second delay). Once the Vacation LED begins to blink, release both buttons.
4. Again, within 10 seconds, press both temperature adjust buttons simultaneously until
Vacation LED is on steady (approx. 5 second delay).
5. Release two buttons, the  microcomputer will clear the FVS lock-out and normal
operation will then be restored.
gas valve setting
White Rodgers
Larger image
Buy
Gas control valve thermostats at Amazon
Gas water heater thermostats at Amazon
Rheem gas control valve at Amazon
Gas control valve at Amazon
Camco White Rodgers at Amazon
Gas water heater timer fits this valve
Replacement instructions
How to replace water heater gas valve
Resources
Service manual
Service manual 2
Service manual 3
Operation and safety
How to light water heater/pdf
General troubleshoot manual /pdf
White Rodgers gas control valve replacement pdf
Power vent water heater issues
Magnet testing
Test thermocouple
Gas valve testing
How to light gas water heater
White Rodgers NG replace, install, set temp
Install, operate and service manual


Robert Shaw 120Volt input gas control valve Wiper Control and Gas Valve assembly Triangle pointed upward is 120 degrees F Replacement for Rheem power vent/
Buy
Rheem wiper SP20123A thermostat KIT
Wiper SP20123B valve/ no thermostat


Resources
Larger image 
Error Codes and troubleshoot
Guardian power vent Robert Shaw error code
Check the blower motor, gas control etc
Rheem parts list
American power flex parts
General manual with lighting instructions
Replace water heater gas control and FV
Check pressure switch, blower, gas control
Sequence of operation
How to light water heater
To reset: turn the red control knob on and off 6 times within 30 seconds to reset the board.

White Rogers thermostat

Buy
Camco White Rodgers at Amazon

Resources
Troubleshooting/ pdf
How to light gas water heater
How to replace water heater gas valve


Remove gas valve
Buy
Buy universal gas control wrench
Honeywell Smart Valve AO Smith
Honeywell Smart Valve
Larger image

Resources:
Temperature settings and features
Smart valve error codes
Service manual
Service manual 2
Install smart valve & troubleshoot
Light commercial power vent/ install maintain, service
Low NOX
Ruud/ direct vent install, maintain, service
Ultra low nox install, maintain, error
Ultra low nox install, maintain, error
Low-nox-burner-parts.pdf
Low-nox-Training_Manual.pdf
Ultra-low-nox-power-vent-manual.pdf
Venting resources
Installation manuals above all show venting specifications
Power vent venting
High wind vent cap
Sidewall Power direct vent
Residential-code-for venting gas appliances.pdf
AO Smith Vertex high efficiency
ULTRA HIGH EFFICIENCY POWER VENT service
Manufactured homes
American direct vent install, maintain, service
AO smith direct vent install, maintain, service
14 things needed for gas water heater & .pdf resources
What you need for operation of gas water heater.
General troubleshoot
1) Basic parts and operation
2) Adequate incoming air supply ... issues: closed doors, tightly insulated house, very hot attic.
3) Adequate air supply getting to burner... issues: dirty vent screen, dirty environment, maintenance.
4) Thermal cutoff  ... TCO ... issues: failed part, maintenance, vent.

5) Flammable vapor lockout .... issues: exposure to vapors, bad FV sensor, failed FV system,
6) Fuel supply to gas valve thermostat ... natural gas and propane are different ... issues: wrong gas, low pressure, moisture in pipe, undersized gas meter, supply line too small for BTU rating.
7) Gas valve thermostat regulates fuel supply ... issues: not enough gas, failed thermostat, failed gas control valve.

8) Fuel supply from thermostat to burner ... issues: maintenance, thermocouple-thermopile, gas control valve.
9) Clean and replace burner ... issue: periodic maintenance requires burner inspection, cleaning, and possible replacement

10) Functioning thermopile-thermocouple-pilot light ... issues: misalignment, failure of part.
11) Ignition of fuel supply by pilot light or hot surface igniter ... issues: pilot light, piezo igniter, electrode.

12) Power vent water heater troubleshoot ... issues: pressure switch, blower, blower sequence from gas control, outlet polarity
13) Venting combustion byproduct .... issues: vent in disrepair, other vents in house drawing air

14) Misc troubleshoot manuals
15) How to install gas water heater
16) How to maintain water heater

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Buy water heaters from my associate links:

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Resources:
How to install gas water heater
How to install electric water heater
Troubleshoot gas water heater
Troubleshoot electric water heater
Point of use water heaters
Resources:
Troubleshoot Gas valves with manuals
Icon gas valve

How to replace water heater element Waste King disposal
How to wire tankless electric


Install point of use water heater
Titan tankless

Contactors/ relays
Type 1 and type 2 surge protection surge protection
Programmable timers

Woods timers
surge protection
Anode rods anode rods
Recirculation system

Tankless recirculation
Point of use water heater
Install and troubleshoot garbage disposal Waste King disposal
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Electronic parts

Industrial supplies

Tools and home improvement

Home and garden

Hayward pool
Pentair pool

Southwire electric
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Tools

DEWALT
Black and Decker
Stanley
SKIL
Makita
Porter-Cable
Bosch

Irwin Hand tools
Klein hand tools
Fluke electrical testing
Dremel hobby tools

Campbell Hausfeld air powered
Tekton automotive

Powerbuilt automotive
Saws and saw blades
box timers Resource:
Compare box timers
DPDT timers
Intermatic
Control water heater w/ Z-wave
Intermatic control centers Resource:
Intermatic control centers: and parts
Digital control centers and parts
Tork control centers and parts
Subpanels
All control centers and parts
Enclosures
programmable timer Resource:
Programmable timers
Countdown timers
Off delay timers
On delay timers
Timer modules
Din rail
Twin & one-shot
Plug-in timers
Woods
Intermatic
Tork
Low voltage power packs Recirculation systems
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