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air supply for gas water heater
Image of Bradford white air intake
Bradford White water heaters
to 10 things for troubleshooting water heater
1) Incoming air supply
Water heater must have enough air to support combustion.
Well-insulated house or closed doors can prevent adequate air from reaching water heater.
Very hot attic will cause oxygen molecules to spread too far apart to support combustion.
AO Smith and 3-legged water heaters have air intake located on bottom of heater (install heater on 3 bricks to elevate space under heater), Bradford White (pictured) has air intake on side.
Do not install gas water heater in small contained area, use louvered doors, do not pile belongings around water heater. Get fresh air to water heater and see if problem is resolved.
|"UNCONFINED SPACE is space whose volume
is not less than 50 cubic feet per 1,000 Btu per hour (4.8 cubic meters
per kW) of the aggregate input rating of all appliances installed in
that space. Rooms communicating directly with the space in which the
appliances are installed, through openings not furnished with doors,
are considered a part of the unconfined space.|
In unconfined spaces in buildings, infiltration may be adequate to provide air for combustion, ventilation and dilution of flue gases.
However, in buildings of tight construction (for example, weather stripping, heavily insulated, caulked, vapor barrier, etc.), additional air may need to be provided.
"CONFINED SPACE is a space whose volume is less than 50 cubic feet per 1,000 Btu per hour (4.8 cm per kW) of the aggregate input rating of all appliances installed in that space.
confined space shall be provided with two permanent openings communicating directly with an additional room(s) of sufficient volume so that the combined volume of all spaces meets the criteria for an unconfined space. The total input of all gas utilization equipment installed in the combined space shall be considered in making this
determination. Each opening shall have a minimum free area of one square inch per 1,000 Btu per hour (22 cm2/kW) of the total input rating of all gas utilization equipment in the confined space, but not less than 100 square inches (645 cm2). One opening shall commence within 12 inches (31 cm) of the top and one commencing within 12 inches (31 cm) of the bottom of the enclosures."
|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.
AO Smith air intake on bottom of heater shown
to 10 things for troubleshooting water heater
2) Air supply getting to burner
Air intake must be clean. If intake is blocked, the combustion flame is yellow and lazy instead of crisp and blue. Water heater might not stay lit.
See manual for location of air intake.
Do not install water heater in dusty environment.
Avoid dusty environment that will clog air intake, cause unburned fuel, and create fire hazard.
Some FV designs can trip if the air intake is clogged.
Avoid dust and dirt. Dirty, dusty environments pose hazards for all gas appliances. Water heater air intake will clog, and shut down burner or cause FV lockout. FV lockout
Location of AO Smith/ American/ Kenmore/Whirlpool 3-legged water heater with arrestor screen that will clog with dust.
If screen is clogged or restricted, the unit might go into lockout. First sign of trouble might water heater that will not light, Reset TCO thermal cut off located on front of unit and check color of flame. Lazy yellow flame indicates poor incoming air supply, or poor venting.
Get adequate fresh air to unit and clean vent screen located on bottom of AO Smith products.
If water heater will not light, then do steps above and continue troubleshoot using 14 steps listed below.
Inspect and Clean air intake on AO Smith, State, American, Reliance, Whirlpool water heaters using feather duster or compressed air.
Set 3-legged water heater on bricks so air intake is easily accessed.
Flame trap inspection mirror at Amazon
Check the vent
Reset TCO thermal cut off
Larger image Bradford White air intake
Bradford White, Rheem, Richmond, Ruud, GE heaters require removal of combustion parts to clean arrestor screen located inside unit.
How to clean combustion chamber
How to troubleshoot FV lockout
should burn clear blue
Lazy yellow flame indicates one or more of following:
a) Poor incoming air supply, covered this page
b) Inadequate venting. Troubleshoot vent
c) Dirty combustion parts. Clean combustion chamber
d) Low gas pressure. Check gas pressure and thermostat
Very hot attic causes oxygen molecules to spread too far apart to support pilot light.
Increase ventilation to water heater
Attic ventilation/ pilot outage pdf
Exposure to corrosive environments such as pool chemicals, process chemicals, bleach can damage burner parts.
Air is drawn into water heater, and if air contains trace amounts of chemical, or chemicals are burned in the flame, this will damage water heaters over time, and shorten life of water heater.
"Chemical vapor corrosion of the flue and vent system may occur if air for combustion contains certain chemical vapors. Spray can propellants, cleaning solvents, refrigerator and air conditioner refrigerants, swimming pool chemicals, calcium and sodium chloride, waxes, bleach and process chemicals are typical compounds which are potentially corrosive."
Remove chemicals from same room as water heater.
-Chemicals that will corrode water heater parts and vent pipe include: 'Spray propellants, cleaning solvents, refrigerants, swimming pool chemicals, calcium and sodium chloride, household bleach, waxes and process chemicals ... all these chemicals are corrosive at very low levels with no odor."
Chemicals can damage burner parts
Do not expose water heater to stored chemicals, swimming pool chemicals, laundry equipment
Remove chemicals from same room as water heater.
-Chemicals corrode water heater parts and vent pipe. 'Spray propellants, cleaning solvents, refrigerants, swimming pool chemicals, calcium and sodium chloride, household bleach, waxes and process chemicals are corrosive at very low levels with no odor."
Poor venting can damage parts
When there is inadequate draw, the water vapor cools and condenses on inside wall of vent pipe. This condensation water is acidic (pH 3-5) and corrosive. It will corrode steel metals and other materials.
Improper venting causes water to drip down vent into combustion chamber of gas water heater. Parts inside combustion chamber rust. Holes develop in bottom of water heater. Inspect combustion chamber for rust and water.
Avoid corrosive atmospheres / pdf
Read Bradford White Pdf pg2-8
Read Rheem pdf
Avoid corrosive atmospheres
|14 things needed for gas water heater & .pdf resources|
|What you need for
operation of gas water heater.
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
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