Aprilaire 800 Series Troubleshooting Manual page 3

d. Check condensate pump function by engaging the float.
12. If Humidifier is OFF:
a. Remove the canister door and override the interlock switch with a small c-clamp.
b. Verify internal wiring per Appendix A.
c. Turn ON; ensure the On/Off green LED is lit. Humidifier will not produce steam unless
there is a call for humidity.
Using Lights to Troubleshoot
1. On/Off Green Light not on, humidifier is Off and/or power is not supplied. If humidifier will not
power up when On/Off button is depressed:
a. Check reset switch on transformer. If it is tripped, reset it (75 VA transformer only).
b. Check the breaker at the power supply to the humidifier.
c. Verify humidifier is properly wired to line voltage.
d. Check LED (D8) on circuit board (4" from the bottom of the board) is glowing green, if
not illuminated and power is supplied to the humidifier check for 24V at the transformer
terminals by removing the connector at P4 and inserting a volt meter into the connector
on the transformer.
i.
ii.
iii. Transformer Part Numbers:
e. If control board LED is on, but On/Off Light will not energize when On/Off switch is
depressed. Replace Membrane switch (Part Number 5532).
2. Yellow Steam Light: humidifier has been operating for 168 hours but has not reached full
capacity. The humidifier is making steam and is working to get to full capacity, boiling action
concentrates minerals in the canister (the more minerals in solution, the higher the amperage and
therefore output). To help speed this up:
a. Set the furnace to constant fan or use the blower activation feature on the Model 62
control. This allow the humidifier to run as needed to provide humidity.
b. Increase the humidity setting on the control (do not over humidify the home as damage
can occur from condensation).
c. If available, plumb to softened water. Sodium does not precipitate out of solution easily,
this allows the water conductivity to rise quickly compared to Calcium in hard water.
Expect to see more drain cycles as a result.
d. Wire humidifier to 240VAC.
NOTE: Canisters should be changed every season. If the canister has not been changed,
capacity will be significantly reduced or inoperable.
If 24V is present but LED does not light, replace circuit board (Part Number
5530). If there is voltage other than 24V, remove power to the humidifier at the
circuit breaker and move the jumper wire to the correct terminal on the PCB.
If 24V is not present then check input power to the transformer by checking
voltage between L1 and L2/N on connector P5.
If input power is correct, replace transformer, if no input power to the transformer,
check line power wiring.
1) Model 800 and Model 801 (40VA): 5529.
2) Model 865 and Model 866 (75VA): 5306.
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