Specifications

INTERNAL CONTROLLER - FEATURES OF OPERATIONS
The internal controller within the humidifier cabinet responds to external inputs (e.g., humidistat and airflow proving switch) and
internal inputs (e.g., water level probe inside the steam chamber) to provide:
• Relative humidity (RH) control
– Model 1150: With an on-off demand signal, the controller
maintains RH within 5% to 7% of set point.
– Model 1160 and 1180: With a modulating demand signal,
the humidifier maintains RH within 2% to 4% of set
point. Modulating demand signal options include a 0–10
VDC humidistat signal (humidistat provided), or a signal
by others (0–10 VDC or 4–20 mA).
• Automatic water level control and safety shut-down
If there is insufficient water, an electronic water level
probe sends a signal to the controller to add water or to
turn off the heaters. (See Figure 5.)
• Operating time monitoring
The controller accumulates humidifier run time to activate
end-of-season draining, water cool-down, and auto draining.
• Automatic preheating
– Model 1160 and 1180: During normal operation, in the
case of a re-fill cycle or a period of no demand for
humidity, the controller will recognize that the tank has
cooled down. The heaters will energize for an
appropriate amount of time to bring water close to
boiling temperature. Preheat only occurs when there is
a demand for humidity.
• Automatic end-of-season draining
If the humidifier doesn’t receive a humidity demand signal
for 72 hours, the chamber automatically drains.
• Periodic drain and flush
To reduce mineral buildup in the chamber, the humidifier
automatically drains at intervals based on operating time,
output capacity, and water type. At the end of the drain
cycle, the supply water is brought on to briefly flush the
chamber.
• Chamber water cooling before draining
To ensure that water is at or below 140°F (60°C) before
discharging to the plumbing system, the humidifier remains
idle for a defined period of time before draining.
• Ensuring duct airflow
The humidifier will not make steam unless the HVAC
system blower is on and the airflow proving switch verifies
there is airflow in the duct.
OVERVIEW OF HUMIDIFIER OPERATION
The humidifier monitors and controls water levels electronically
using a three-rod probe. The humidifier responds with the above
actions when the water level reaches each probe rod.
VLC-OM-030
FIGURE 5 – Electronic Water Level Probe
Fill valve closes
Fill valve opens
Low-water cutoff
7