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period of 0-240 seconds set by programmable
parameter DRN 1). For setting of this blow down time,
refer to the GHMC Display Manual, form #274.
Figure #25
HIGH WATER LEVEL AND
OVERFLOW PROTECTION
During this time water will be drained from the top
portion of the tank and blow down the drain until the
timed cycle is complete.
The fill valve is disabled following the above
sequence until water level in the tank drops below float
"B" (due to evaporation). At that time the above
sequence is repeated. If the water level ever falls
below float "G" the burner(s) will shut down to prevent
any damage to the unit.
.
SEQUENCE OF OPERATION
Provided the necessary power, water, gas and
vent connections are completed, the' unit is started by
the activation of the on/off switch located on the front
panel.
When the operating humidistat and safety controls
are closed, the ignition module will energize the igniter.
The hot surface igniter then heats up, and after about
seven seconds, the gas valve is energized. The
burner will then be lit and the igniter will stop glowing.
If the burner flame is not sensed by the flame sensor
within 4 seconds, the gas valve will shut off and this
cycle will be repeated a maximum of three times.
When the humidity in the space matches the setting of
the operating controller, the burners will shut down and
the unit will remain idle until the next call for humidity.
SLOWDOWN CALIBRATION
The gas humidifier will periodically "blowdown" or
skim water from the tan k to reduce the concentration
of total dissolved solids that accumUlate during long
term operation. Gas Humidifiers are shipped factory
set at maximum blowdown (approximately 20% of
output). This setting ensures that scale build-up will
be minimized for all water conditions. The amount of
blowdown is field adjustable. Two parameters will help
determine the proper blowdown setting of the
Gas-Fired Humidifier
• Water hardness
• Silica content
Water Hardness
Inspection Interval
Blowdown Potentiometer Setting
0..
(located on the electrical panel behind the locked door)
:I:
All GHB and GHP Models
(!)
"C
,
c
<4 grains
Annual
Between low & midpoint
<U
CD
f
:I:
4-10 grains
Semi-Annual
Between midpoint and maximum
(!)
.
>10 grains
Bi-monthly
Maximum
.
Water
Inspection
Blowdown DRN1 Setting
Hardness
Interval
GHMC 100
GHMC 200
GHMC 300
GHMC 400
•
U
<4 grains
5 to 10
:i
15 to 19
23 to 28
33 to 38
:I:
(!)
·
4-10 grains
Semi-Ann ua/
10 to 14
19 to 23
28 to 32
38 to 42
!
.............
•
Bi-monthly
14+
23+
*Refer to GHMC instruction manual for programming instructions.
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