InSTallaTIon InSTRUCTIonS
(ConTInUeD)
aUToMaTIC DIGITal ConTRol anD aCCeSSoRy wIRInG (MoDel 800)
The control circuit operates on 24VAC .
The ADHC (Automatic Digital Humidifier Control) Model 62 must be mounted in the return air duct at least 6” upstream of any fresh air intake
ducts or sources of moisture and at least 12” upstream of the steam dispersion tube if it is mounted in the return . Follow instructions provided
with the control . Connect “H” terminals on ADHC to “HUMIDISTAT” terminals on humidifier circuit board . The “H” terminals on the Model 62
provide a dry contact switch to energize the humidifier .
If the application requires a wall-mounted humidistat in the conditioned space, use Manual Humidistat Part #4655, Digital Manual Humidistat
Part #65, Automatic Digital Modulating Humidistat Part #63 or any Aprilaire thermostat with integrated humidifier control functionality . Use
Blower Activation Relay Part #4851 with Aprilaire Manual and Digital Manual Humidistats in order to allow the humidifier to turn on the HVAC
system blower when humidity is required .
If protection from over-humidification is desired, install optional high humidity limit switch Part #4594 at least 4 feet downstream of the
dispersion tube . If airflow verification is desired, install optional airflow proving switch Part #4592 in duct . The high humidity limit switch and the
airflow proving switch are wired in series with the ADHC (humidistat) circuit . See
figure 17
.
24 VAC from HVAC
Equipment “R” & “C”
Communication with
Aprilaire 8570 Thermostat
Outdoor Temperature Sensor
Heat Signal from HVAC Equipment
Fan Signal from Thermostat
Fan Signal to HVAC Equipment
MODEL 62 DIGITAL HUMIDIFIER CONTROL
24V TERMINALS
OPTIONAL:
AIR FLOW PROVING SWITCH #4592
Connect 1/4" plastic tubing from H (High) side
of proving switch to the airflow sensing probe
located 1.5 duct diameters downstream of
blower. Leave L (Low) side open to amosphere.
OPTIONAL:
HIGH HUMIDITY LIMIT SWITCH #4594
Switch breaks C to NC connection when
measured RH is above setpoint RH.
H Gf
R C A B ODT
G
W
H
FA
N P
ACK
HUMIDIS
TAT
C NO NC
C
NO
NC
fIGURe 17 – Steam Humidifier accessory wiring
90-1544
20
