Armstrong 6100 - Page 12

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High Limit Humidistat
Remove the jumper tab from ground and in of high limit/pressure switch connections and wire the high
limitstatbetweentheseterminals.RefertoFigure10-1(theoverallwiringdiagram)formoreinform
ation. A duct mounted high limit humidistat is recommended to prevent over-saturation of the duct air.
Useanon-offcontrollerthatopensonfault(highhumidity).Humidistatshouldbesetforamaximum
of90%RH.Locatethehighlimithumidistatapproximately3m(10feet)downstreamofthedispersion
manifold.If3m(10feet)isnotavailable,consultthefactory.Note: High limit humidistat will be wired in
series with duct pressure switch, if used, see Figure 10-1.
Airflow/Pressure Switch
An airflow switch is recommended to deactivate the humidifier when there is insufficient air flow in a
duct system. A duct pressure switch is preferred as an airflow sensor. The pressure switch should
openoninsufficientairflow(opensonfault).Airflowswitchshouldbemountedinsupplyairduct
upstream of humidifier dispersion. Remove the jumper tab from ground and in of high limit/pressure
switchconnectionsandwiretheairflowsensorbetweentheseterminals.SeeFigure10-1(theoverall
wiringdiagram)formoreinformation.Completeinstallationandwiringinstructionsarecontainedinthe
duct pressure switch package.
State light will flash green if either high limit or air pressure switches are open.
Modulating High Limit Humidistat/Sensor
AmodulatinghighlimithumidistatmaybeusedonapplicationssuchasVariableAirVolume(VAV)
or in situations where the duct RH required to maintain the room set point is near saturation. The
modulating high limit alleviates the humidifier from operating in on/off if working near the high limit set
point. See Figure 10-1 or Figure 11-2 for wiring.
Alarm Circuit
Theterminals3&4(normallyopenrelayexternalalarm)areconnectionsforaclassIINECalarm
circuit(switchclosureonly,1amp.maximum@24Vdcor0.5amp.@125Vac).Theswitchwillclose
if the unit encounters an error or when service life has expired it will not engage if high humidity/sail
switch circuit is open.