Low Water Flow/Pressure - Bosch C 950 ES Installation Manual

Troubleshooting
and check all taps for water flow. There should be no
water flowing. Any continuous flow of water, small or
large, indicates a crossover and must be corrected.
Consult a professional plumber for help in correcting a
crossover. Failing single lever faucet mixing valves are
common causes of plumbing crossovers.
8. Ensure the temperature sensor is making contact and
firmly mounted on the hot water pipe.
7.5

Low water flow/pressure

1. Too many hot water applications are being used
simultaneously or too much flow is demanded. The
water heater will effectively support two 2.0-2.5 GPM
shower heads simultaneously
applications. Greater draws will result in a water
pressure drop and reduced flow at taps.
2. Ensure that gas pressure is in accordance with
specifications in chapter
pressure reading is needed to proceed further. Contact
your original installer or a local certified gas technician
to obtain this reading. If gas pressure is inadequate, the
water heater will close its motorized water valve,
reducing the hot water flow rate in an attempt to reach
the selected output temperature.
3. If selected temperature on the unit is set too high for the
demanded flow rate, the water heater will close its
motorized water valve, reducing the hot water flow rate
in an attempt to reach the selected output temperature.
Lowering the selected temperature will allow the
motorized water valve to open up for increased water
flow rate.
4. Clean inlet filter screen per chapter
5. Inspect the water path for obstructions. Make sure all
showerheads, faucet aerators and whole house filters
are clear of debris.
7.6 Hot water temperature fluctuates
at tap
1. Hot water is very hot out of the water heater, requiring
mixing in cold water in order to attain a useable hot
water temperature. The addition of too much cold will
overpower hot water flow from the tankless water
heater.
If this slows the flow through the tankless water heater
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.bosch-climate.us 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
48
or multiple sink
3.14 , page 35 . A gas
6.1 , page 41 .
6.1 , page 41 for inlet filter cleaning
chapter
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.
7.7 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
10 .
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 Section
24 Combustion Air Requirements.
4. Cross contamination. Ensure that intake and exhaust
terminations maintain required clearances as stated in
chapter 3.3 , page 10 . 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
adjustment. This will result in unstable burner flames
and noise. Ensure gas pressure is in accordance with
specifications in Section
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
2
CO adjustments must be done by a certified gas
2
technician with a calibrated combustion gas analyzer.
3.3 , page
3.4 , page
) to be out of
2
3.14 , page 35 Measuring
6.5 , page 43 .
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