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MANUAL CAPACITY ADJUSTMENT
The NHB humidifier is rated in lbs/hr of steam
output capacity. Set to 100%, it will operate at full
output until the humidistat has sensed that the
humidity has reached setpoint. Then it will stop the
humidifier by breaking control circuit 8-10.
If the humidifier is oversized, the humidistat will be
quickly satisfied and stop the humidifier. As humidity
level drops the humidistat calls again. It is quickly
satisfied and stops again. The resultant short-cycling
is easily overcome.
A manual capacity adjustment potentiometer
(“pot”) is provided on the NHB main pc board for that
purpose. It is marked “Sx%” and is adjustable from 20
to 100% of rating.
The NHP humidifier, utilizing modulation control,
does not have the same problems of oversizing. It
reacts to the modulation signal and varies its capacity
automatically. However, if you wish to turn down the
capacity, the NHP has the same manual capacity
adjustment potentiometer (“pot”) that the NHB has.
OTHER POTENTIOMETERS
Do not adjust any other potentiometers (“pots”) on
the pc board(s). They are factory-set and not meant to
be user-set.
DETECTING WATER SUPPLY DEFICIENCY
Knowing how long it normally takes to fill each size
steam cylinder, each humidifier’s pc board is factory
configured to an acceptable maximum filling time
(using jumpers). If it is filling too slowly, when the time
expires the electronics stops the humidifier. To
indicate this, the green light goes out and the yellow
light goes on.
REMOTE INDICATION
Every NHB/NHP comes factory wired to provide
24 VAC (100 mA max.) at 61-20 on the control
terminal strip. The user can connect an indicator
externally to 61-20. It will automatically be activated
any time the yellow light is on. It will therefore be
activated whenever the humidifier shuts off due to
excess current or water deficiency. It is also normal
for it to be activated on start-up.
DOUBLE UNIT OPERATION
Turn both switches on. If there is a demand for
humidity, the green status lamp will indicate that the
circuit is operating.
On the NHP, the optional output indication meter
will steadily increase until the meter reads maximum
output. Maximum output depends on the manual
capacity setting of the unit and/or the continuous
control demand.
The NHB/NHP has built in diagnostic capabilities
and will shutdown for the following reasons:
-
No current (similar to NHMC Error Message 5).
-
Excess current (similar to NHMC Error Message 1).
-
Change cylinder/end of life (similar to NHMC Error
Message). NHB will shutdown on this fault.
In all cases, when an error is detected, there will
be 24 VAC potential (100 mA max.) available at
terminals 20 and 61 of the internal external white
terminal strip.
BLOWER PACK OPERATION
Blower packs are equipped with a control
thermostat mounted on the steam distributor. As soon
as humidifier generates steam, the contact is closed
and the fan is started. When steam is no longer being
generated, the fan cuts out with a delay.
If blower packs get overheated (malfunction of the
air circulation), the manual reset safety thermostat
interrupts the steam generation. To reset, switch off
the humidifier and wait until the steam distributor cools
down. Then remove left-hand side intake air filter and,
using a screwdriver, press the reset button (marked
with a red dot) inside the blower packs.
Units are equipped with speed select switch. The
switch is located on the right-hand side of the blower,
inside the blower pack. To access the switch, remove
right-hand side intake air filter.
To avoid condensation on the cabinet parts, run
blower pack on high speed when humidifier delivers 75
lbs/hr or 100 lbs/hr of steam.
MAINTENANCE
WARNING! The plumbing and electrical
compartments contain high voltage components and
wiring. The access door(s) is equipped with a lock.
Access should be limited to authorized personnel only.
WHEN TO REPLACE THE STEAM
CYLINDER
The steam cylinder is disposable and must be
replaced at end of cylinder life. Cylinder life is
-10-