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Page 2
2008-10-01
1. PRINCIPLE OF OPERATION
A. Combustion System
(1) The combustion system is based on a fully modulating forced draft combustion air
blower, a negative pressure regulated gas valve, and a 100% premix burner. On a
call for humidity, the combustion air blower starts and creates a negative pressure
across an orifice located at the air inlet.
(2) The blower is energized to purge the system, then the hot surface igniter is activated.
During this time the electronic ignition module does a diagnostic check of safety
systems including the air-proving switch, which senses the negative pressure at the
air inlet orifice. After the function of the safety systems has been verified, the gas
valve will open and the gas/air mixture is ignited by the hot surface igniter.
(3) If a flame is sensed by the flame sensor, the gas valve remains open and
combustion continues. If a flame is not sensed, the above sequence is repeated to a
maximum of three times after which the ignition module will lock out. The gas valve
maintains a constant ratio air to gas independent of blower speed or external
conditions. This air and fuel is thoroughly mixed in the blower and then forced
through the burner ports where ignition occurs.
(4) Hot products of combustion are forced through a baffle inside the heat exchanger
and then vented outside. The heat exchanger has a large flat surface to minimize
scale build-up and promote scale shedding to the bottom of the tank. This self-
cleaning action helps to maintain the efficiency of the heat exchanger while the
smooth surfaces allow for easy cleaning when necessary.
(5) The GS 100 has a single removable combustion chamber/heat exchanger. The
combustion system is duplicated on larger units with multiple chambers inside a
common tank.
Table 1. Technical Data
UNIT TYPE
SPECIFICATION GS 100 GS 200 GS 300 GS 400
GS 500
GS 600
Rated Capacity: lbs/hr* 25-105 25-210 25-315 25-420
25-525
25-630
Rated Capacity: kg/hr* 11-48 11-95 11-143 11-191
11-238
11-286
Input BTU/hr max 140,000 280,000 420,000 560,000
700,000
840,000
Input kJ/hr max 41 82 124 165
206
247
Flue Emissions Low CO (< 10 ppm) and Low (NOx <40 ppm)
GSTC/GSP Rated Amps 1.1 1.9 2.7 3.5
4.3
5.2
Voltage/Phase 208-240/1 Standard
GSTC Outdoor Rated Amps 3.2 4.0 6.9 7.7
10.6
11.5
Voltage/Phase 208-240/1 Standard
GSTC/GSP Rated Amps 2.1 3.7 5.3 6.8
8.4
10
Voltage/Phase 120/1 Standard
GSTC Outdoor Rated Amps 6.3 7.4 13.7 15.2
21.0
22.6
Voltage/Phase 120/1 Standard