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To perform hydrostatic test:
1. Connect fill water supply. Fill heater with water.
Carefully fill the rest of the system, making sure
to eliminate any entrapped air by using high-point
vents. Close feed valve. Test at standard operating
pressure for at least 24 hours.
2. Make sure constant gauge pressure has been
maintained throughout test.
CAUTION: Damage due to internal condensation
A
may occur if the heater inlet water temperature does not
exceed 120°F (49°C) within 7 minutes of start-up.
3. Check for leaks. Repair any that are found.
Cold Water Operation
This heater is equipped with a proprietary condensate
evaporation system which will evaporate any condensate
that may begin to accumulate inside the primary heat
exchanger with water temperatures as low as 120°F
(49°C).
Heaters operated with an inlet temperature of less than
120°F (49°C) MUST have an approved low-temperature
operation system (Figs. 10 and 11) to prevent problems
with condensation. Inlet water temperatures below 120°F
(49°C) can excessively cool the products of combustion,
resulting in collection of condensate in the heat exchanger
area beyond the capacity of the condensate evaporation
system.
Failure to reach or exceed 120°F (49°C) may damage or
cause failure of the heat exchanger, combustion chamber,
or other parts within the combustion chamber. It can cause
operational problems, bad combustion, sooting, flue gas
leakage and reduced service life of the appliance and the
vent system.
A bypass allows part of the heater discharge water to be
mixed with the cooler water returning to the heater inlet to
increase the heater inlet temperature above 120°F (49°C).
This precautionary measure should prevent the products
of combustion from condensing beyond the ability of the
condensate management system employed in this heater
in most installations. Warranty claims will be denied for
damage or failures caused by condensation.
Cold Water Starts
Cold water starts, where the inlet water temperature
remains below 120°F (49°C) must have cold water start
protection. Known protection methods consist of mixing
heated outlet water with the inlet water using a bypass to
raise the inlet to 120°F (49°C) or higher. Once the system
is heated up and has return water temperatures of 120°F
(49°C) or higher, the mixing of outlet water with inlet water
is no longer needed and the bypass can be shut off. If the
bypass is not shut off as the system heats up, the outlet
temperature may continue to climb and trip the high limit,
thereby shutting down the heater. Thus an automatic valve
14
system, such as a three-way proportional valve to control
the bypass, should be used.
T & P GAUGE
BYPASS
SYSTEM
AB
SYSTEM
TEMP
PRESSURE
MAIN
SYSTEM
PUMP
SYSTEM
RETURN
Figure 9.
Cold Water Start
Cold Water Run
Cold water run differs from cold water start in that the
system water entering the heater remains below 120°F
(49°C) continuously. Typically, this is the case in water
source heat pump applications as well as some others.
An injector pump arrangement may be used to keep the
heater loop at or above 120°F (49°C). An injector pump
approach has the added value of being able to adjust
automatically to changes in the system water coming back
to the heater.
T & P GAUGE
SYSTEM
TEMP
SENSOR
MAIN
SYSTEM
PUMP
SYSTEM
RETURN
DIAMETER, NOT
TO EXCEED 12"
Figure 10. Cold Water Run
COLD WATER
HEATER
TEMP SENSOR
LOCATED IN
INLET HEADER
B
A
MAXIMUM 4
TIMES THE
SYSTEM
SYSTEM PIPE
RETURN
DIAMETER, NOT
TO EXCEED 12"
(305 mm)
HEATER
INJECTOR
PUMP TEMP
SENSOR
BOILER
PUMP
INJECTOR
PUMP
MAXIMUM 4
TIMES THE
SYSTEM
SYSTEM PIPE
RETURN
(305 mm)
F10677
F10678
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