Armstrong 6100 - Page 25

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Humidifier runs continuously, %RH is well under set-point.
1.Verifyhumidistat/RHsensoriswiredcorrectlyanddipswitches(S2&S3,SeeFig.10-1,11-1 
 and11-1)onthePCboardaresetcorrectlyforthehumidistatsignal.
2.Checkhumidistatdemandsignalatlowvoltageterminalstrip.Itshouldbecloseorat100%.
3. If humidifier is a three phase model, verify all three phases of power are present and equal.
4. Check amperage draw on all high voltage power lines with a clamp on amp meter. They should be
same or very close to amperage rating on the humidifier’s nameplate if the humidistat demand is
 100%.
5. Turn off power. Disconnect heating elements and check resistances - see Tables on Pages 35 and
 37.Ifanopencircuitorabnormallyhighresistanceismeasured,theheatingelement(s)is
defective. Also, check to see if heating element leads have shorted to ground.
6. If heating elements are OK, check voltages at secondary side of the power module and contactor.
If no or low voltage, check primary fusing.
7. If fuses are OK, check voltage to contactor coil.
 (a)Ifvoltageis24-28VACatcontactorcoil,checkcoilresistance.Itshouldbeapproximately 
8W? with wires disconnected. If resistance is OK, check voltage drops across the contactor.
 (b)Ifnovoltagetocontactorcoil,checkcontinuityofwiresfromPCboardtocontactor.If  
continuity is OK, PC board is likely defective.
8. Checkvoltagesignaltopowermodule.ThevoltageacrossTAB8-1andTAB8-2(lowvoltagesignal
  topowermodule)shouldbe12Vdcat100%power.
 (a) Ifnoorlowvoltage,thePCboardislikelydefective.
 (b) IfvoltageisOK,butgreen“LOAD”LEDonthepowermoduleisnoton,powermoduleis 
defective.
9. If green “SIGNAL” LED on power module is on, check voltage drops across power module.
10. If supply voltage and amperage draws are correct and elements appear OK, unit is probably
 undersized(notenoughcapacityfortheapplication).Checksizingorconsultfactory.
Humidifier does not drain when manual drain.
1. Disconnect and check resistance of drain valve coil. Resistance should be approximately
10W(8.3W HC-6500/6700).
2. Make sure drain line is pitched and sized correctly. Check for blockage or obstructions in the drain
line. An air gap or funnel must be used as described in Drain Line Section. - See Figure 8-3.
3. If humidifier does not drain at specified interval or when service is to be performed and drain
valve and piping appear OK, there is blockage of the tank drain screen or the PC board may be
defective.