American Water Heater 40 Gallon 38000 BTU Direct Vent Natural Gas Water Heater DVG6240S38NOV user manual

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CERTIFIED GAS 
SUPPLY FLEX PIPE 
(PROPERLY SIZED 
FOR THE HEATER 
INPUT RATE)
SEDIMENT 
TRAPGAS 
CONTROL 
VA LV E GROUND 
JOINT 
UNION 
(OPTIONAL)
CAP
3” 
MIN.
Figure 13 
BLACK PIPE
SEDIMENT 
TRAPGAS 
CONTROL 
VA LV E GROUND 
JOINT 
UNION 
(OPTIONAL)
CAP
  3”  MIN.
Figure 14 
 SEDIMENT  TRAP
• Contaminants in gas lines can 
cause fire or explosion.
• Clean all gas piping before 
installation.
• Install sediment trap in accor-
dance with NFPA54.Fire and Explosion Hazard
WARNING
 
A sediment trap should be installed as close to the inlet of 
the water heater as practical at the time of water heater 
installation. The sediment trap should be either a tee fi tting 
with a capped nipple in the bottom outlet or other device 
recognized as an effective sediment trap. If a tee fi tting is 
used, it should be installed in conformance with one of the 
methods of installation shown in Figure 13 & Figure 14.
Contaminants in the gas lines may cause improper 
operation of the gas control valve/thermostat that may 
result in fi re or explosion. Before attaching the gas line be 
sure that all gas pipe is clean on the inside. To trap any 
dirt or foreign material in the gas supply line, a sediment 
trap (sometimes called a dirt leg) must be incorporated in 
the piping. The sediment trap must be readily accessible. 
Install in accordance with the “Gas Piping” section. Refer 
to the current edition of the  
“National Fuel Gas Code” 
(ANSI Z223.1/NFPA 54) .
 HIGH  ALTITUDE  INSTALLATIONS
Installations above  7,700’ . require replacement of the 
burner orifi ce in accordance with the current edition of 
the  
“National Fuel Gas Code” (ANSI Z223.1/NFPA 54). 
Failure to replace the orifi ce could result in improper and 
ineffi cient operation of the appliance, producing carbon 
monoxide gas in excess of safe limits, which could result 
in serious personal injury or death. Contact your gas 
supplier for any specifi c changes which may be required 
in your area.
Breathing carbon monoxide can cause brain damage or death.
Always read and understand instruction manual.
• High altitude orifice must be 
installed for operation above 
7,700 ft.
• Contact a qualified installer or 
service agency.
Breathing Hazard - Carbon Monoxide Gas
WARNING
    
						

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 VENTING
This direct vent water heater uses a sealed venting 
system to supply fresh combustion air to the heater and 
to exhaust the products of combustion (fl ue gases) to the 
outdoors. The venting is a “pipe in a pipe” system. The 
inner (3”) piping carries out the exhaust fl ue gases while 
the outer (6”) piping carries in fresh combustion air. The 
corrugated end of the vent piping connects to the top of 
the water heater and the opposite end connects to the vent 
termination hood which will be mounted on the exterior wall 
(see Figure 16). Figure 16 shows the hot exhaust gas exit 
and the location of the combustion air intake.
Figure 19 thru Figure 26 show how to assemble and 
connect the venting system.
Figure 28 thru Figure 30 show various installation options.
DO NOT STORE OR USE GASOLINE OR OTHER 
FLAMMABLE VAPO RS AND LIQUIDS IN THE VICINITY 
OF THE VENT TERMINATION HOOD.
NEVER OPERATE THE WATER HEATER UNLESS IT IS 
VENTED TO THE  OUTDOORS AND  HAS ADEQUATE AIR 
SUPPLY TO AVOID RISKS OF IMPROPER OPERATION, 
FIRE, EXPLOSION OR ASPHYXIATION.
DO NOT OBSTRUCT THE FLOW OF COMBUSTION AND 
VENTILATING AIR. ADEQUATE AIR  FOR  COMBUSTION 
AND VENTILATION MUST BE PROVIDED FOR SAFE 
OPERATION.
 
**Minimum 12 in.
Minimum 12 in.
above grade or
anticipated snow
level
Minimum 12 in.
under veranda, porch,
deck or balcony
(see footnote 1)
Minimum
3 ft.
above if within
10 ft.
horizontally to
a mechanical air
supply inlet
Minimum 9 in. to a non mechanical air supply inlet
into building or combustion air inlet to another appliance Minimum 12 in.
from soffit *Minimum 9 in. to
 a window or door
 that may be opened
**Minimum
18 in.
from outside
corner
1. Permitted only if veranda, porch, deck or balcony is fully opened on a minimum of two sides beneath the floor.
2. A vent shall not terminate above a sidewalk or paved driveway that is located between two single family dwellings and serves both dwellings. AREA WHERE TERMINAL IS NOT PERMITTED VENT TERMINAL AIR SUPPLY INLETMinimum
3 ft.
clearance to a 
service regulator
vent outlet** Or as required by local authorities.
Figure 15 
Breathing carbon monoxide can cause brain damage or death.
Always read and understand instruction manual.
• Install vent system In accordance with codes.
• Do not operate water heater if flood damaged.
• Install water heater in accordance with the 
instruction manual.
• Do not operate if soot buildup is present.
• Do not obstruct water heater air intake.
• Do not place chemical vapor emitting products near 
water heater or vent terminal hood.
• Gas and carbon monoxide detectors are available.
• Never operate the heater unless it is vented to the 
outdoors and has adequate air supply to avoid risks 
of improper operation, fire, explosion or asphyxia-
tion.
• Analyze the entire vent system to make sure that 
condensate will not become trapped in a section of 
vent pipe and therefore reduce the open cross 
sectional area of the vent.
• Chemical corrosion of flue and vent system can 
cause serious injury or death.
Breathing Hazard - Carbon Monoxide Gas
WARNING
 VENT TERMINAL CLEARANCES
The vent system must terminate so that proper clearances 
are maintained as cited in local codes or the current edition 
of the  
“National Fuel Gas Code”, ANSI Z223.1/NFPA 
54 as follows: 
						

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FRESH 
COMBUSTION 
AIR IN
HOT 
EXHAUST 
GAS OUT
SCREW
Figure 16 
Be sure venting is properly connected to prevent escape 
of dangerous flue gases which could cause deadly 
asphyxiation.
 DV TERMINATION SAFETY COVER
When the heater is in operation the vent termination hood 
will be hot (see Figure 16).
A Safety cover (see Figure 17) is available to prevent 
accidental contact with the vent terminal. Contact your 
Customer Service Department for ordering information.
Figure 17 
Alternatively, a wire mesh or louvered fencing guard can 
be built around the termination as shown in Figure 18.
Figure 18 
 VENT  CONNECTIONS
After the location for the vent terminal has been selected 
as outlined in Figure 6 & Figure 15, use the following 
illustrations for installation:
 LOCATING CLEARANCE HOLE FOR VENT
Cut a clearance hole, approximately  7”  in diameter, through 
the exterior wall for the vent assembly. The recommended 
height is  64”  for  40 gal.  models,  73”  for  50 gal.  models 
and  74”  for  50 gal.  Hi-Input models, as measured from 
the hole center to bottom of water heater. Where the 
wall is combustible and the wall thickness is over  14” ,  1”  
clearance to combustible surfaces around the vent terminal 
is needed. The fi rst  14”  is zero clearance (see Figure 21).
 STANDARD  VENT  ARRANGEMENT
* If the horizontal length of the venting is less than  30”  
the restricter plate must be installed (see Figure 22, Figure 
28 thru Figure 30).
• Do not use the restricter plate in an offset installation 
(see Figure 26).
• Do not use the restricter plate the horizontal length of 
the venting is greater than  30” .
Note: The length of “unstretched” corrugated tube could 
cause the length of the vent run to exceed the minimum. In 
this case cut off a piece of the corrugated tube to achieve 
the  17”  minimum vent length.    
						

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 VENT  ASSEMBLY
The vent piping and the vent termination hood are to be 
connected as shown in Figure 20.
Maintain vent clearances to combustibles as shown in 
Figure 21.
Depending on your access to where the vent termination 
passes through the wall, you may wish to connect the 
piping and vent termination hood together fi rst.
Inside the vent piping there are springs that hold the two 
corrugated pipes in position. When the pipes are stretched 
to the required length, the springs will remain properly 
spaced.
To connect the vent piping to the vent termination hood, 
fi rst slide the inner (3”) corrugated pipe over the inner vent 
termination pipe. Continue this action until the locking 
clip on the corrugated pipe snaps into position in the 
corresponding groove (see Figure 19). Secure corrugated 
pipe with screw (supplied) inserted through hole opposite 
the locking clip.
Repeat this process with the outer (6”) corrugated pipe and 
lock it into position on the outer pipe on the vent termination 
(see Figure 19). Secure corrugated pipe with screw 
(supplied) inserted through hole opposite the locking clip.
Note: To reduce the friction between the corrugated pipe 
and the O-rings, it is recommended to dampen the O-rings 
with water.
The completed connection is shown in Figure 20.
INNER 
CORRUGATED PIPEINNER VENT 
TERMINATION PIPEOUTER VENT 
TERMINATION PIPE
O-RING OUTER 
CORRUGATED 
PIPE
LOCKING CLIP 
GROOVE LOCKING 
CLIP
Figure 19 
SCREW
Figure 20 
 SECURING VENT TERMINATION ASSEMBLY TO 
THE EXTERIOR WALL
Some models are supplied with trim plates which may 
be used to cover the holes in the wall (see Figure 1 and 
Figure 21). Slide one trim plate (if supplied) over the outer 
corrugated tube, then insert the outer corrugated tube 
through the clearance hole from exterior wall. Secure 
the trim plate to the exterior wall, then secure the vent 
terminal to the exterior wall with 4 screw anchors (included) 
appropriate for the type of wall construction. Caulk the 
junction of the vent terminal base plate and the exterior 
wall with exterior type sealant (not included). Slide the trim 
plate (inside) over the outer corrugated tube and fasten the 
trim plate to the interior wall. Caulk the junction of the outer 
corrugated tube and the trim plate (inside) with suitable 
sealant. The vent termination hood attaches to the vent 
piping as shown in Figure 20.
TRIM PLATE 
(INSIDE)TRIM PLATE 
(OUTSIDE)
APPLY 
SEALANT SPRING
CUTAWAY TO 
SHOW SPRING 
PLACEMENT
APPLY 
SEALANT
  14”  ZERO 
CLEARANCE  1”  
CLEARANCE
Figure 21 
 VENT RESTRICTER PLATE
The vent restricter plate (see Figure 22) is required for 
short horizontal runs on low vent installations (see Figure 
29) and high vent installations (see Figure 30).
For short horizontal vent runs (see Figure 29) place the 
restricter plate over the fl  ue tube reducer before connecting 
the inner corrugated tube to the fl ue tube reducer. DO 
NOT use the restricter plate if the horizontal run is greater 
than  30” .
For high vertical runs use the restricter plate only when 
the vertical run of the venting above the heater is greater 
than  48”  (see Figure 30).
UPPER AIR 
INLET BOX FLUE TUBE 
REDUCER
RESTRICTER 
PLATE
Figure 22 
 UNCOMPRESSING THE CORRUGATED TUBING
1.  Pull the inner corrugated tube towards the water heater 
and leave some length over the water heater’s center 
for bending (see Figure 23).
2.  Pull the outer corrugated tube toward the water heater 
and leave it  2”  shorter than the inner corrugated tube.
3.  Make sure there are two springs evenly spaced at the 
bend in the tube.
4.  Use metal hangers to keep venting level or with a 
slope upward from the heater to terminal.     
						

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INNER 
CORRUGATED 
PIPEOUTER 
CORRUGATED PIPE
RESTRICTER 
PLATEFLUE TUBE 
REDUCER
APPLY 
SILICONE
Figure 23 
 VENT CONNECTION TO THE WATER HEATER
Bend both the corrugated pipes toward the fl ue connection 
on the water heater. Pull and connect the inner corrugated 
pipe to the water heater’s fl ue tube reducer with hi-temp 
red silicone (included) and gear clamp. Make sure this 
connection is tight and leak proof (see Figure 24).
*The sealant between the inner corrugated pipe and water 
heater’s fl ue tube reducer must be hi-temp red silicone 
or other material suitable for  600°F  continuous service.
Note: If you are using the vent restricter plate, the inner 
vent pipe is to go over the side legs and down the stops.
SMOOTH, 
EASY CURVE
GEAR 
CLAMP
CUTAWAY TO 
SHOW DETAILS
RESTRICTER 
PLATE STOP
Figure 24 
Apply hi-temp red silicone (included) around the collar on 
air manifold box. Pull the outer corrugated pipe all the way 
on to collar and secure with the gear clamp. Pull the free 
end of the corrugated pipe past the gear clamp and secure 
with one sheet metal screw (see Figure 25).
GEAR 
CLAMP
APPLY 
SILICONE 
TO AIRBOX 
BEFORE 
ATTACHING 
PIPING
SECURE 
WITH A 
SHEET METAL 
SCREW
SMOOTH, 
EASY CURVE
Figure 25 
 OFFSET  VENT  ARRANGEMENT
Where a straight vent arrangement is impossible, a 
horizontal 90° maximum bend can be made. Use the 
water heater casing outer diameter as a template to form 
the corrugated tube.
SMOOTH, 
EASY CURVE
90° 
MAXIMUM 
BEND
Figure 26 
Figure 27 
Note: To ensure good exhaust gas fl ow, bend vent piping 
using a smooth, easy curve as shown in Figure 24 thru 
Figure 26. Do not use reverse or compound curves as 
shown in Figure 27.       
						

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ABOVE 
ANTICIPATED 
SNOW 
LEVEL OR 
  12”  ABOVE 
GRADE
A
B
Low Vent installation
7
6
8
1
C
519
Figure 28 
DIM. 4038 5040 5047
A 80”  MAX.
B 9”  MIN.
C 
(RECOMMENDED)  63.63”  73.00”  74.00” 
C 
(MINIMUM)  60.75  69.50  70.50 
D 14.25”  MIN.
NOTE: Dimension “C” is the height above to fl oor to the center of the 
termination hole through the exterior wall.
D
4
Minimum Vent installation
C
ABOVE 
ANTICIPATED 
SNOW 
LEVEL OR 
  12”  ABOVE 
GRADE3
  9” 
Figure 29 
 
12”  MIN. 
BELOW 
SOFFIT
  72”  
MAX.
6
2
High Vent installation
51
1
  17”  
MIN.
Figure 30 
NOTES: (applies to Figure 28 thru Figure 30)
1.  In any installation the total of dimension “A” plus 
dimension “B” must not exceed  89” .
2.  This heater can be installed with  0”  clearance to a wall.
3.  Minimum vent pipe clearance to combustibles is  1”  
(see Figure 21).
4.  Minimum distance from center of heater to wall is 
  14.25” .
5.  Dimension “A” includes wall thickness.
6.  Hole diameter in wall is  7” .
7.  Venting must slope up away from the heater a 
minimum of  0.25” per foot  of length to prevent 
condensation from collecting and to provide 
suffi cient draft.
8.  Distance above horizontal at full extension is  2” .
9.  Use support stays to hold the venting to avoid sags 
or valleys.    
						

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 INSTALLATION  CHECKLIST
Note: Use and complete this checklist before lighting the 
heater. Correct any conditions that do not meet these 
instructions.
 Water Heater Location
  Centrally located with the water piping system. 
Located as close to gas piping and vent pipe system 
as possible.
  Located indoors and in a vertical position. Protected 
from freezing temperatures.
  Proper clearances from combustible surfaces 
maintained and not installed directly on a carpeted 
floor.
  Provisions made to protect the area from water 
damage. Metal drain pan installed and piped to an 
adequate drain.
  Installation area free of corrosive elements, flammable 
material and flammable vapo r emitting products.
  Sufficient room to service the water heater.
 Gas Supply and Piping
  Gas supply is the same type as listed on the water 
heater data plate.
  Gas line equipped with shut-off valve, union and 
sediment trap.
  Adequate pipe size and of approved material.
  Approved pipe joint compound or tape used.
  Chloride-free soap and water solution or other 
approved means used to check all connections and 
fittings for possible gas leaks.
 Vent Pipe System
  Evenly stretched out between water heater and vent 
termination hood.
  Smooth bend with adequate support to prevent 
sagging,  0.25” per foot .
  Inside pipe (3”) and outside pipe (6”) securely 
fastened to vent termination hood.
  Vent restricter plate installed on heater flue outlet as 
applicable.
  Inside pipe (3”) and outside pipe (6”) securely fastened 
to water heater with silicone and gear clamps.
  Not obstructed in any way. Vent Termination Hood
  Securely fastened to exterior wall.
  Above anticipated snow level or  12”  above grade.
  Proper clearances from windows, doors, corners, 
other vent openings etc.
  Area around vent termination hood clear and 
unobstructed.
  No flammable vapo r emitting products stored nearby.
  Safety covers in place (when applicable).
 Water System Piping
  Temperature-Pressure relief valve properly installed 
with a discharge line run to an open drain and 
protected from freezing.
  All piping properly installed and free of leaks.
  Heater completely filled with water.
  Closed system pressure build-up precautions installed.
  Mixing valve installed (when applicable).
After all actions on checklist are checked/
completed, read the Lighting Instructions and 
proceed with lighting the heater. 
						

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LIGHTING INSTRUCTIONS
1.  Turn the gas control/temperature knob counterclockwise        to the OFF position. The status light will stop 
blinking and stay on for a short time after the water heater is turned off. See Figure ‘A’.
329352-000
TO TURN OFF GAS TO APPLIANCE
1.  STOP! It is imperative that you read all safety warnings before lighting the pilot.
2.  Turn the gas control/temperature knob counterclockwise        to the OFF position.
3.  Wait ten (10) minutes to clear out any gas. If you then smell gas,  STOP! Follow “ B” in the safety 
information above on this label. If you do not smell gas, go to  the next step.
4.  Turn the gas control/temperature knob clockwise        to “PILOT”. See Figure ‘B’.
5.  Press the gas control/temperature knob all the way in and hold it in. The knob should travel in about 1/4 inch if 
it is set to PILOT correctly. While holding the gas control/temperature knob in, click the igniter button 
continuously (about once a second) for up to 90 seconds or until status light begins to blink. The pilot flame 
should envelop the thermopile. See Figure ‘D’.
6.  When the status light starts blinking, release the gas control/temperature knob. Set the gas 
control/temperature knob to the desired setting. See Figure ‘C’.
  • If the status light does not start blinking within 90 seconds, repeat steps 2 through 5 up to THREE (3) times, 
waiting 10 minutes between lighting attempts.
  • The circuitry in this advanced gas valve requires that you wait 10 minutes between lighting attempts.
  • If the status light turns a solid color, release the gas control/temperature knob and repeat steps 2 through 5 
(waiting 10 minutes before attempting to relight the pilot). If the status light does not start blinking after 
three lighting attempts, turn the gas control/temperature knob to the OFF position and call a qualified 
service technician or your gas supplier.
DANGER: Hotter water increases the risk of scald injury. Consult the instruction manual before 
changing the temperature setting.
  Refer to the Lighting Instructions in the Installation Manual for more detailed troubleshooting information.
DANGER:
FIGURE  D
Main Burner
Thermopile Pilot FlameFIGURE  A
OFF POSITIONFIGURE  B
PILOT POSITIONFIGURE  C
ON POSITION
120°F
Mark120°F
Mark
CONTROL KNOB
120°F
Mark
GAS CONTROL
Gas Control & 
Temperature Knob
Status
Light
Igniter
Button
LIGHTING INSTRUCTIONS
A.  This appliance has a pilot which is lit by a piezoelectric spark gas ignition system. Do not open the inner door 
of the appliance and try to light the pilot by hand.
B.  BEFORE LIGHTING smell all around the appliance area for gas. Be sure to smell next to the floor because 
some gas is heavier than air and will settle on the floor.
WHAT TO DO IF YOU SMELL GAS
  • Do not try to light any appliance.
  • Do not touch any electric switch; do not use any phone in your building.
  • Immediately call your gas supplier from a neighbors phone. Follow the gas suppliers instructions.
  • If you cannot reach your gas supplier, call the fire department.
C.  Use only your hand to push in or turn the gas control knob. Never use tools. If the knob will not push in or 
turn by hand, dont try to repair it, call a qualified service technician. Force or attempted repair may result in a 
fire or explosion.
D.  Do not use this appliance if any part has been under water. Immediately contact a qualified installer or service 
agency to replace a flooded water heater. Do not attempt to repair the unit! It must be replaced!
BEFORE LIGHTING: ENTIRE SYSTEM MUST BE FILLED 
WITH WATER AND AIR PURGED FROM ALL LINESFLAMMABLE
WARNING: If you do not follow these instructions exactly, a fire or explosion may 
result causing property damage, personal injury or loss of life.
FOR YOUR SAFETY READ BEFORE LIGHTING
  
						

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TEMPERATURE REGULATION
 TEMPERATURE  REGULATION
 
 Temperature  Adjustment
Valves for reducing the point-of-use temperature by mixing 
cold and hot water are available (see Figure 8). Also 
available are inexpensive devices that attach to faucets to 
limit hot water temperatures. Contact a licensed plumber 
or the local plumbing authority.
Note: During low demand periods, a lower thermostat 
setting will reduce energy losses and may satisfy your 
normal hot water needs. If hot water use is expected to 
be more than normal, a higher thermostat setting may be 
required to meet the increased demand. When leaving 
your home for extended periods (e.g., vacations etc.) turn 
the temperature dial to its lowest setting. This will maintain 
the water at low temperatures with minimum energy losses 
and prevent the tank from freezing during cold weather.
GAS CONTROL VALVE/THERMOSTAT 
SETTINGS
GAS CONTROL/
TEMPERATURE KNOB
STATUS 
LIGHT
IGNITER120°F 
MARK130°F 
MARK155°F 
MARK 150°F 
MARK 140°F 
MARK
91°F 
MARK
 
Figure 31 
The thermostat is adjusted to the “OFF” position when 
it is shipped from the factory. Water temperature can be 
regulated by moving the temperature dial to the preferred 
setting. The preferred starting point is  120°F  at the “HOT” 
setting. Align the knob with the desired water temperature 
as shown in Figure 31. There is a hot water scald potential 
if the thermostat is set too high.
Note: Temperatures shown on the gas control valve/
thermostat are approximates. The actual temperature of 
the heated water may vary.
Important: Adjusting the thermostat past the  120°F  mark 
on the temperature dial will increase the risk of scald injury. 
Hot water can produce fi rst degree burns within:
Water 
Temperature 
  °F Time for 1st
Degree Burns
(Less Severe Burns)Time for Permanent 
Burns 2nd & 3rd 
Degree (Most 
Severe Burns)
  110  (normal shower temp.)
  116 (pain threshold)
  116  35 minutes 45 minutes
  122  1 minute 5 minutes
  131  5 seconds 25 seconds
  140  2 seconds 5 seconds
  149  1 second 2 seconds
  154 instantaneous 1 seconds
(U.S. Government Memorandum, C.P.S.C., Peter L. Armstrong, 
Sept. 15,1978)
Table 2
Should overheating occur or the gas supply fail to shut off, 
turn “OFF” the manual gas shut-off valve to the appliance 
(see Figure 1, item 18).
   OPERATING THE TEMPERATURE CONTROL 
SYSTEM
 Water  Temperature  Adjustment
The water temperature setting can be adjusted from  91°F  
to  155°F . Turn the Gas Control Valve/Temperature Knob 
to the desired setting/temperature.
Note: The temperatures indicated are approximates. The 
actual temperature of the heated water may vary.
 Operating Modes And Settings
Standard Mode - The controller adjusts the water heater 
to maintain the temperature set by the user.
Setting for vacation - The “LOW” position sets the controller 
at approximately  91°F . This setting is recommended for 
times when the water heater will not be in use for an 
extended period of time. It effectively turns the controller 
temperature setting down to a temperature that prevents 
the water in the water heater from freezing while still 
conserving energy.  
						

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FOR YOUR INFORMATION
 EXTERNAL  DAMAGE
Do not operate the water heater until it has been fully 
checked out by a qualifi ed technician, if the water heater:
• Has been exposed to fi re or damage.
• Displays evidence of sooting.
• Produces steam or unusually hot water.
If the water heater has been fl ooded it must be replaced.
 START UP CONDITIONS
NEVER OPERATE THE HEATER WITHOUT FIRST 
BEING CERTAIN IT IS FILLED WITH WATER AND A 
TEMPERATURE AND PRESSURE RELIEF VALVE IS 
INSTALLED IN THE RELIEF VALVE OPENING OF THE 
HEATER. DO NOT ATTEMPT TO OPERATE HEATER 
WITH COLD WATER INLET VALVE CLOSED.
   Condensate
Whenever the water heater is fi lled with cold water, some 
condensate will form while the burner is on. A water 
heater may appear to be leaking when in fact the water is 
condensate. This usually happens when:
a.  A new water heater is fi lled with cold water for the 
fi rst time.
b.  Burning gas produces water vapo r in water heaters, 
particularly high efficiency models where flue 
temperatures are lower.
c.  Large amounts of hot water are used in a short time 
and the refi ll water in the tank is very cold.
Moisture from the products of combustion condense on 
the cooler tank surfaces and form drops of water which 
may fall onto the burner or other hot surfaces to produce 
a “sizzling” or “frying” noise.
Because of the suddenness and amount of water, 
condensate water may be diagnosed as a “tank leak”. 
After the water in the tank warms up (about 1-2 hours), 
the condition should disappear.
Do not assume the water heater is leaking until there has 
been enough time for the water in the tank to warm up.
An undersized water heater will cause more condensation. 
The water heater must be sized properly to meet the 
family’s demands for hot water including dishwashers, 
washing machines and shower heads.
Excessive condensate may be noticed during the 
winter and early spring months when incoming water 
temperatures are at their lowest.
Good venting is essential for a gas fi red water heater 
to operate properly as well as to carry away products of 
combustion and water vapo r.
 Smoke/Odo r
It is not uncommon to experience a small amount of smoke 
and odo r during the initial start-up. This is due to burning off 
of oil from metal parts, and will disappear in a short while.
 THERMAL  EXPANSION
Water supply systems may, because of such events as 
high line pressure, frequent cut-offs, the effects of water 
hammer among others, have installed devices such 
as pressure reducing valves, check valves, back fl ow 
preventers, etc. to control these types of problems. When 
these devices are not equipped with an internal by-pass, 
and no other measures are taken, the devices cause the 
water system to be closed. As water is heated, it expands 
(thermal expansion) and closed systems do not allow for 
the expansion of heated water.
As water is heated, it expands (thermal expansion). As the 
volume of water increases, there will be a corresponding 
increase in water pressure due to thermal expansion. 
Thermal expansion can cause premature tank failure 
(leakage). This type of failure is not covered under the 
limited warranty. Thermal expansion can also cause 
intermittent temperature-pressure relief valve operation: 
water discharged from the valve due to excessive pressure 
build up. The temperature-pressure relief valve is not 
intended for the constant relief of thermal expansion. This 
condition is not covered under the limited warranty.
A properly-sized thermal expansion tank should be 
installed on all closed systems to control the harmful 
effects of thermal expansion. Contact a plumbing service 
agency or your retail supplier regarding the installation of 
a thermal expansion tank.