GBT A2-035, Инструкция по установке и эксплуатации

Страница: 19 / 45

Page 18
OPERATION
The A2000 models are simple ON/OFF water heater/boilers. The units are turned ON and OFF by the
application or removal of 120 VAC power to the control panel. Normally, this 120 VAC power is provided
through an operating thermostat. Safety controls (such as a flow switch and manual reset water high limit
temperature switch) installed between the operating thermostat and the heater/boiler prevent power from
reaching the control panel if water flow is not present, or the outlet water temperature has been exceeded.
When 120 VAC power is applied to the heater/boiler control panel on a call for heat from the operating
thermostat, 24 VAC is applied to the Ignition Control Module via a transformer. The ICM provides spark to the
igniter, opens the pilot burner operating valve providing gas flow to the pilot burner, and looks for flame
verification through the spark igniter electronics. Once pilot flame is verified, the ICM opens the automatic main
burner valve(s), which provides gas flow to the main burner, which is ignited by the pilot burner.
If the pilot flame is not verified, the ICM will try to light the pilot burner two
more times (see CSD-1 Section below for control differences specific to
CSD-1 models). After the third try, the ICM will go into lock-out. The ICM
can be reset by removing power to the heater/boiler. The pilot burner
remains ON the entire time the main burner is ON. If pilot flame verification
is lost while the main burner valves are ON, the ICM will close the main
burner valves and try to re-establish pilot burner flame.
When the operating thermostat is satisfied, the 120 VAC is removed, and the
normally closed pilot valve and main burner valves close.
Operating Thermostat Setting: A separate operating temperature controller is required for proper operation of
this appliance. Failure to install a separate operating temperature controller will result in short cycling. Water
heaters are expected to operate at temperatures between 120 °F and 155 °F (49 to 68
o
C) Water boilers can
operate with return water temperature up to 190 °F (88
o
C) and a supply temperature up to 240
o
F (115
o
C).
Return water temperatures must be kept above 120 °F to prevent condensation. Refer to the DIAGRAMS
section for recommended piping for lower operating water temperatures. Frequent operation below 120°F (49
o
C) return water temperature will damage the heat exchanger and void the warranty .
Do not operate your A2000 heater/boiler with return water temperatures lower than
120
o
F (49
0
C). Consistent operation below these temperatures will cause heat
exchanger corrosion and void the warranty.
When the heater/boiler is used for potable water heating, use a
mixing valve or similar means to reduce the potable water
supply temperature to avoid scald injuries. The mixing valve
should be set at the lowest possible temperature that provides
useful service for the application. For potable water uses, 120
– 125
o
F (49 – 51
o
C) is recommended.
Water temperatures higher than 125
o
F
(51
o
C) can cause severe burns,
personal injury or loss of life. The
temperature at which injury occurs
varies with a persons age and the time of exposure. Never
allow small children to use a hot water tap or draw their
own bath water.
Water High Limit Switch: Every A2000 model is equipped with a manual reset, High Limit Switch on the hot
water outlet. For water heater models, the high limit has a factory stop of 200
o
F (93
o
C). For boiler models, the
factory stop is set at 240
o
F (115
o
C). The high limit switch must always be present and must never be by-
passed. If the High Limit Switch trips, it must be manually reset by pressing the red button, located on the front
cover of the High Limit Switch.
deg F deg C
> 170 > 77
160 71
150 65
140 60
130 54
120 49
Water Temperature - Scald Relationship
Water Time to Produce
Temperature 2nd & 3rd Degree
Burns on Adult Skin
Nearly Instantaneous
About 1/2 Second
About 1-1/2 Second
Less Than 5 Seconds
About 30 Seconds
More Than 5 Minutes
Ignition Control Module (ICM)