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2. Water flow through the heater is higher
than the capacity of the AquaStar to heat it
If the AquaStar flow restrictor has been removed,
the flow through the heater might be higher than
its capacity to heat it. Reduce the flow to a range
within which the heater can maintain temperature.
See flow chart on Page 18. AquaStar water heat-
ers have a (removable) flow restrictor to assure
that the maximum volume flowing through the
heater remains in the range that the heater can
2. Gas pressure too low
Very low gas pressure may be caused by low
delivered gas pressure, by a jammed gas regu-
lator or by undersized gas lines. If the gas lines
are undersized, there may still be the specified
static gas line pressure. However, when the wa-
ter valve opens, the pressure will drop sharply,
causing the pilot flame to go out. Have a gas
service person confirm the gas pressure both
statically and at maximum Btu input. Specifica-
tions for your heater are on page 3.
3. Burners are not shutting down immedi-
ately when hot water is turned off
If burners don't shut off
immediately
when hot
water is turned off, the heater will overheat and
the ECO will shut off the gas. Replace all three
parts in the water valve assembly (parts #21107,
34542, 32570. (See Letter R, Fig 2, page 6).
WATER IS TOO HOT
1. Temperature setting is too high
Unlike storage tank heaters which need to be set
at a higher temperature than is needed in order
to stretch the volume of hot water by mixing in
cold water, an AquaStar can be set for the exact
temperature needed and give endless hot water
without need for mixing in cold water. We rec-
ommend setting the temperature selector dial on
#4 or #5. For more information, see section on
Setting Water Temperature, Page 12.
2. Inlet water temperature is too high (as with
preheated water)
Note: Only the Model "S" AquaStar should be
used if the inlet water is preheated.
3. Thermostat is not functioning properly
(See #1 under PILOT LIGHT GOES OUT DUR-
ING OR AFTER HOT WATER USE)
WATER IS NOT HOT ENOUGH
1. Temperature dial is set too low
Change the setting.
heat to a suitable temperature, regardless of how
many faucets are being used. This is to ensure
that the flow is never higher than what the heater
can heat to a suitable temperature. The AquaStar
model 80 flow restrictor is set for a maximum of
2.2 gallons per minute. Note: In private well in-
stallations, the high and low cycling control of your
water pump may be set too low or the pressure
tank may be water logged.
3. BTU input is too low due to insufficient gas
pressure
It is extremely important for a tankless water
heater to have the right size gas line to ob-
tain the correct gas pressure.
See specifications for correct gas pressures on
page 3. Unlike storage tank water heaters, the
burners of a tankless water heater must be very
powerful to heat water instantaneously since they
do this only at the time hot water is actually being
used. It is
imperative
that the gas pressure re-
quirement be met exactly. Insufficient gas pres-
sure will directly affect the water temperature.
Static gas pressure in the line can be measured
at the pressure test nipple located on the
AquaStar manual shut-off valve (Letter L, Fig 2,
Page 6). Manifold pressure may be tested at the
manifold presure test nipple (Letter G).
4. BTU input is too low due to insufficient gas
supply
Make sure your main gas line is fully opened. If
using LP gas, minimum size of the propane tank
should be 100 pounds for best results.