30
BULLETIN 15
CONDENSATION
SYMPTOMS
The water heater appears to be releasing water while the main burner is on or water
is found surrounding the heater shortly after the water heater has been used. This
bulletin explains why
fl
ue gases condense and how you can differentiate between
condensation and leaking.
CAUSES
Condensate is the result of air borne water vapor being chilled below the dew point.
The dew point is the temperature at which water vapor turns into liquid. Low incoming
water temperatures cool the piping and the heat transfer surfaces of the water heater.
When the main burner comes on, the hot
fl
ue gases turn into condensate upon contact
with these surfaces. The typical home water heater will produce about one-half gallon
of water vapor during every hour of operation. Condensate is often mistaken for
leaking.
Newer heaters will condensate more than older heaters because modern water heaters
are much more ef
fi
cient than their predecessors. The newer heaters utilize as much of
the energy out of the main burner
fl
ame as possible. This lowers the
fl
ue gas and tank
storage temperature and closer to the dew point temperature.
DIAGNOSIS
To distinguish between a condensating water heater and a leaking water heater:
1. Wipe up any water under the heater.
2. Turn the knob on the thermostat to the pilot position.
3. Wait 8 hours, check for water accumulation under the heater.
4. Condensation should stop when the entire tank water is heated above
approximately 115 degrees.
• If no water is under the heater, the water heater was condensating.
• If water is under the heater, check further for a loose
fi
tting. If all
fi
ttings are
tight and the tank is leaking, replace the water heater. Leaking heaters cannot
be “repaired”.
