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below its activation point, it will shut off the burners. The
end result is nothing but cold water coming out of the
outlet.
Consult www.boschheatingandcooling.com for a detailed
service bulletin on overcoming temperature fluctuations.
2. Unbalanced pressure in water lines. Any restriction in the
water heater, such as a clogged inlet filter screen, can result
in unequal pressures between the cold and hot water lines.
In such cases, when mixing in the higher pressure cold
water at the tap, the lower pressure hot water can be
overpowered. This will shut down the burners because the
hot water flow rate fell below the minimum flow rate
required for activation. Verify inlet filter screen is clean and
clear of debris. See chapter 7.1, page 56 for inlet filter
cleaning instructions.
3. Heater deactivated by temperature balancing valves. If the
outlet water temperature is set too high, the heater can
produce temperatures that are too hot. A temperature
balance shower valve will automatically mix in cold water to
reduce the hot water temperature. In the event of any
temperature instability at a fixture using a temperature
balancing valve, refer to the valve manufacturer for
instructions on internal adjustment setting. An adjustment
should be made to minimize the amount of cold water the
valve is adding. Additionally, the temperature setting on the
heater can be lowered to prevent the temperature balance
valve from mixing in too much cold.
4. Inlet water pressure is erratic due to fluctuating supply
water pressure. For installation on a private well system
with the use of a pressure tank, the lowest pressure range
setting recommended is 40 - 60 psi (2.75 - 4.15 bar).
Consult your installer or local plumber for effective ways to
maintain constant water pressure to the appliance when on
a well system.
8.7
Noisy burner/heater during operation
1. Sealed combustion leak. Make sure combustion cover is
securely fastened. Ensure the exhaust vent adaptor is
properly sealed with supplied gasket. Leaky seals create
improper combustion resulting in noise.
2. Improper venting. Venting that is unsealed, the wrong
material, too big in diameter or too long in run will result in
unstable burner flames and noise. Ensure venting is in
accordance with specifications in chapter 4.3, page 15.
3. Lack of adequate combustion air. Drawing combustion air
from a room area of inadequate size will result in unstable
burner flames and noise. Improper piping of combustion air
to the outside or insufficient space will result in unstable
burner flames and noise. Ensure adequate combustion air
is provided from the unit in accordance with specifications
in chapter 4.4, page 38 Combustion Air Requirements.
C 950/C 1050 (Pro TL 175 C/199 C) – 6 720 805 440 (2019/10)
4. Cross contamination. Ensure that intake and exhaust
terminations maintain required clearances as stated in
chapter 4.3, page 15. Cross contamination between intake
and exhaust may cause unstable burner flames and noise.
5. Lack of gas pressure. Inadequate gas pressure will cause
the fuel-to-air mixture (CO
will result in unstable burner flames and noise. Ensure gas
pressure is in accordance with specifications in
chapter 4.14, page 49 Measuring Gas Pressure. A gas
pressure reading is needed to proceed further. Contact
your original installer or a local certified gas technician to
obtain this reading.
6. Verify proper CO
readings per chapter 7.5, page 59. CO
2
adjustments must be done by a certified gas technician
with a calibrated combustion gas analyzer.
Troubleshooting
) to be out of adjustment. This
2
2
65
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