GBT A2-035, Installation & Operating Instructions Manual

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Relief Valve Operation: Each boiler/water heater is equipped with an ASME approved pressure relief valve,
with a standard setting of 125 psi (862 kPa). The outlet of the relief valve must be piped to a drain or other
suitable safe place in accordance with local codes. When the heater/boiler is connected to a storage tank, a
separate temperature/pressure relief valve must be provided on the tank.
Items Specific To CSD-1 Models:
A2000 models equipped with ASME CSD-1 gas train and controls (model
numbers start with “A2C”) include a factory installed water flow switch in the water hot water outlet, and an
operating thermostat (240
o
F (115
o
C) maximum setting) in the cold water inlet. CSD-1 models are also
equipped with an Ignition Control Module (ICM) that waits five minutes before trying to re-light the pilot burner.
The CSD-1 ICM will not lock out on flame failure; it will continually try to re-light the pilot burner every five
minutes.
Items Specific to 2-Stage Models: Natural Gas A2000 models equipped with a 2-Stage gas valve (model
numbers starting with “A2T” or “A2X”) include an electronic temperature controller with its temperature sensor
installed in the inlet water line. 24 VAC power for the automatic gas control valve, from the ICM, passes through
electronic temperature controller, to either the LOW or HIGH terminal of the 2-Stage gas valve. The 2-Stage
gas valve is factory set to provide 4 inches w.c. gas pressure in HIGH fire mode, and 2.0 inches w.c. in the LOW
fire mode (approximately 70% of nameplate input).
The electronic controller is factory set with both stages in Heating Mode, with Stage 2 set for HIGH fire, and
Stage 1 set for LOW fire. The factory temperature and differential settings are provided in the table below.
When the control is in heating mode, the differential is below the set point.
The relay will de-energize as the temperature rises to the set point.
To change the settings, press the SET button. The screen will display
o
F or
o
C, press the ▲ or ▼ key to change the mode. Press the SET button again to
display the Stage 1 (S1) set point. Press the
▲
or
▼
key to change the set
point, then press SET. The S1 differential will not be displayed. Press the
▲
or
▼
key to change the differential, then press SET. The heating (H1) or
cooling mode (C1) will be displayed. Press SET to keep the control in heating
mode. Press SET again to display the Stage 2 (S1) set point. After setting the
desired temperature, press SET again to display the S2 differential. Press set
again to display heating (H2) or cooling (C2) mode. Press SET to keep control
in heating mode.
Programming is now complete. Programming mode will end if no keys are
pressed for 30 seconds. Any changes will be saved. Settings are stored in
non-volatile memory and will not be lost with power failure.
2-Stage Controller - Factory Set Points
Stage 1 (Low Fire OFF) Set Point 180
o
F
Stage 1 Differential 45
o
F
Stage 2 (High Fire OFF) Set Point 135
o
F
Stage 2 Differential
95
o
F
Low Fire Range: 135
o
F to 180
o
F
High Fire Range: 40
o
F to 135
o
F
Electronic 2-Stage
Temperature Controller
Electronic 2-Stage Temp
Controller – Heating Mode