Humidifiers
www.carnes.com G-5
Humidifiers | Displays & Internal Controls
The Control humidistat, which provides the Control
Demand, is normally the humidistat in the room being
humidified. It is either installed in the room itself or the
return air duct. The High-Limit humidistat, which provides
the Hi-Limit Demand, is a safe-guard humidistat installed
in the supply duct roughly 10-15 feet past the distribution
tube. This humidistat is usually set to a high level (80-
90%), and will shut down the humidifier if the humidity
gets too high in the supply duct. Without a High-Limit
humidistat properly installed, the supply duct could reach
a humidity level where any steam entering the duct would
readily condense.
Both Control humidistats and High-Limit humidistats
are wired in the same way, only Control humidistats
are wired to port J16 of the circuit board and High-Limit
humidistats are wired to port J17. Both ports have the
same number of pins and connection layout.
When using an on/off humidistat, the percentage
should be either 100% or below 20%. In this case the
control is either calling for full output or no output. On-Off
humidistats are dry-contact switches. They will have two
wires; each connected to pins 2 and 4 (in no particular
order/polarity).
For a proportional humidistat, any percentage value is
possible between 0% and 100%. In this case the humid-
ifier can be modified to output any fraction of its max
output. If the proportional control falls to 20% or below,
the humidifier is shut off. The input signal of a proportional
humidistat must be of the 0-10V DC variety. Proportional
humidistats will have three wires, with ‘power’ going to
pin 1, ‘signal’ to pin 3, and ‘ground’ to pin 4.
In lieu of a humidistat, a DDC signal from a building
management system may also be used. Here, the ‘signal’
should be connected to pin 3, and ‘ground’ to pin 4. In
this case, ‘power’ can be ignored. A DDC signal must be
of a 0-10V DC variety, though a 4-20 mA control signal
can be converted to a 0-10V signal by adding a 470 Ohm
resistor between the ‘signal’ (pin 3) and ‘ground’ (pin 4).
“COMPONENT ACTIVITY” PAGE
The Component Activity page lists all internal compo-
nents that can switch on and off during operation. This
includes the Fill Valve, Drain Valve, Contactor, and High
Water Sensor. Each orange button in the component
list is accompanied by a colored indicator representing
whether or not the component is currently ‘on’. Green
indicates that the component is ‘on’, whereas gray
indicates the component is ‘off’. The Fill Valve is on
when the unit is either filling or draining the cylinder.
The Drain Valve is on when the humidifier is draining
the cylinder. The Contactor is on when the humidifier is
producing steam. The High Water Sensor is on when
the humidifier has identified a high water situation. When
The other item present on this screen is the
Communication button. The Communication button has
a rotating indicator that represents whether the True
Touchscreen controller on the circuit board is properly
communicating with the microcontroller. If this icon is not
rotating and has a red ‘X’ through it, the information on
the screen is invalid and you should contact the factory.
“SETPOINTS” PAGE
The Setpoints page displays the setpoints (the target
steam output of the humidifier) associated with the unit.
There are three different setpoints, but only one setpoint
is active at any given time. Each setpoint is accompanied
by the current value of the setpoint to the right, and an
indicator that represents its status. For all setpoints, the
following colors represent the status of the setpoints:
Gray – The setpoint is inactive because it is not
currently necessary.
Green – The setpoint is active, and the humidifier is
producing steam at or above the setpoint value.
Yellow – The setpoint is active, but the humidifier is
producing steam below the setpoint value.
Yellow/Black X – The setpoint is inactive because it is
being overridden by a setpoint with a higher priority.
The three different types of setpoint are as follows: The
Max Setpoint is the user-specified setpoint active when
no external controls or internal reduction is taking place.
The Max Setpoint is always modifiable via the “Max
Output Adjust” within the settings menu. The Controlled
Setpoint is the setpoint when a humidistat (Control or
High Limit), reduces the target output of the humidifier
due to changing room requirements. The Reduced
Setpoint is active when the unit requires a reduction in
output due to a high water situation.
The setpoints have the following priorities: The Reduced
Setpoint has the highest priority and always overrides the
Controlled Setpoint and the Max Setpoint when active.
The Controlled Setpoint has the next highest priority, and
always overrides the Max Setpoint. It should be noted
that the Reduced Setpoint is always lower than or equal
to the Max Setpoint (or Controlled Setpoint, if active),
and the Controlled Setpoint is always lower or equal to
the Max Setpoint.
in a high water situation, the fill valve is disabled for 5
minutes. At the end of 5 minutes the high water sensor
light will go out, the fill valve will open, if there is a call for
more humidity, and unit will continue normal operation.
High water sensors can be cumulative depending on the
condition of the water.
