Start Up Conditions
DRAFT HOOD OPERATION
Check draft hood operation by performing a worst case
depressurization of the building. With all doors and windows
closed, and with all air handling equipment and exhaust fans
operating, such furnaces, clothes dryers, range hoods and
bathroom fans, a match flame should still be drawn into the
draft hood of the water heater with its burner firing. If the
flame is not drawn toward the draft hood, shut off the water
heater and make necessary air supply changes to correct.
CONDENSATION
Whenever the water heater is filled with cold water, a certain
amount of condensation will form while the burner is on. A
water heater may appear to be leaking when in fact the water
is condensation. This usually happens when:
a. When a new water heater is filled with cold water for the
first time.
b. When gas burns and water vapor is produced in water
heaters, particularly high efficiency models where flue
temperatures are lower.
c. When you use large amounts of hot water in a short time
and the refill water 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.
Excessive condensation can cause pilot outage due to water
running down the flue tube onto the main burner and putting
out the pilot.
Because of the suddenness and amount of water, condensa-
tion 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 condensation 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 fired water heater to oper-
ate properly as well as to carry away products of combustion
and water vapor.
SMOKE/ODOR
It is not uncommon to experience a small amount of smoke
and odor 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 flow 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 heat-
ed, it expands (thermal expansion) and closed systems do not
allow for the expansion of heated water.
The water within the water heater tank expands as it is heated
and increases the pressure of the water system. If the relieving
point of the water heater’s temperature-pressure relief valve is
reached, the valve will relieve the excess pressure.
The tem-
perature-pressure relief valve is not intended for the constant
relief of thermal expansion.
This is an unacceptable condition
and must be corrected.
It is recommended that any devices installed which could cre-
ate a closed system have a by-pass and/or the system have an
expansion tank to relieve the pressure built by thermal expan-
sion in the water system. Expansion tanks are available for
ordering through a local plumbing contractor. Contact the
local water supplier and/or plumbing inspector for assistance
in controlling these situations.
STRANGE SOUNDS
Possible noises due to expansion and contraction of some
metal parts during periods of heat-up and cool-down do not
represent harmful or dangerous conditions.
Condensation causes sizzling and popping with the burner
area during heating and cooling periods and should be con-
sidered normal. See “Condensation” in this section.
Operational Conditions
SMELLY WATER
In each water heater there is installed at least on anode rod
(see parts section) for corrosion protection of the tank. Certain
water conditions will cause a reaction between this rod and
the water. The most common complaint associated with the
anode rod is one of a “rotten egg smell”. This odor is derived
from hydrogen sulfide gas dissolved in the water. The smell is
the result of four factors which must all be present for the odor
to develop:
a. a concentration of sulfate in the supply water.
b. little or no dissolved oxygen in the water.
c. a sulfate reducing bacteria within the water heater. (This
harmless bacteria is non-toxic to humans.)
d. an excess of active hydrogen in the tank. This is caused
by the corrosion protective action of the anode.
Smelly water may be eliminated or reduced in some water
heater models by replacing the anode(s) with one of less active
material, and then chlorinating the water heater tank and all
hot water lines. Contact the local water heater supplier for fur-
ther information concerning an Anode Replacement Kit
#9000029 and this Chlorination Treatment.
For Your Information
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