GBT A2-035, Инструкция по установке и эксплуатации

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Page 19
Gas Pressure Regulator:
A gas pressure regulator is provided on all A2000 water heater/boilers. This regulator
is preset at 4 inches water column for natural gas or 10.5 inches water column for Propane gas. For
A2(H,B)035/050 models, the pressure may be adjusted using the adjustment screw located on the combination
gas valve (see Figure on page 16). For all other models, except 2-Stage, a Maxitrol gas pressure regulator is
provided. If a pressure adjustment is required, remove plug and turn screw clockwise to increase pressure,
counterclockwise to decrease pressure. One complete turn will change the pressure approximately ¼ inch of
water column. For 2-Stage models, see the Items Specific to 2-Stage Models below.
Operation of the A2000 heater/boiler at gas manifold pressures greater than 4.0” w.c.
for Natural Gas, and 10.5” w.c. for Propane Gas, will cause the unit to be over-fired,
which may cause premature heat exchanger failure, serious injury, or loss of life.
Flow Switch: A flow switch is required to be installed in the outlet water line, wired so that the heater/boiler will
not fire unless the minimum water flow through the heat exchanger is present. The minimum flow rate for each
model the flow that will provide a 100
o
F (55
o
C) temperature rise through the heat exchanger (see table in
INSTALLATION Section). The set point for the flow switch can be
changed using the adjustment screw located under the electrical house
cover of the switch. Rotate the screw clockwise to increase the flow
set point, counter-clockwise to decrease the flow set point. With the
heater/boiler firing (make sure 2-Stage models are firing on HIGH),
slowly close the manual valve in the water outlet piping, until the
temperature rise through the heat exchanger approaches 100 °F (or
lower based on specific installation or requirements). Adjust the switch
set point so that the switch opens at this flow rate. Slowly open the
water valve so that the switch closes, then repeat the process to
ensure the switch is set correctly.
Risk of electrical shock. Be careful not to touch live electrical parts or bare wires
inside the flow switch housing. The voltage to the flow switch is 120 VAC.
Water Pump: All A2000 models require forced circulation of the water through the heat exchanger. Selection
and installation method of the pump depends upon the design of the system and intended use (see DIAGRAMS
section for water pump location suggestions). The pump electrical power must be wired independently and
should be adequate for the amp rating of the pump motor. Refer to the INSTALLATION section for pressure
losses through the A2000 heat exchangers.
The maximum flow rate through the A2000 heat exchanger is
56 gpm due to velocity induced tube erosion. A list of acceptable water pumps and manufacturers for
the A2000 models is listed on the following page.
Water High Limit Switch –
Manual Reset
Maxitrol Gas Pressure Regulator