Aprilaire 800 Series - Operating Modes

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6. Turn the furnace blower to constant fan.
7. Turn the steam humidifier On. If humidifier fails to turn On, verify power at the input power
terminal block
8. The canister will fill to the high water pin and begin to heat water to make steam.
9. If the humidifier does not begin to fill within 15 seconds:
a. Ensure the two electrode wires and high water pin (yellow wire) on the top of the canister
are attached and fully seated.
b. Remove the high water pin wire from the high water pin on the canister
i. If the humidifier begins filling, reinstall the high water pin, turn the humidifier Off
to allow it to fully drain, and then replace the canister (Part Number 80).
ii. If the humidifier does not begin to fill in five seconds, shut the humidifier Off and
remove the humidistat jumper installed in step 4:
1) Verify that the saddle valve is open.
2) Remove the yellow high water pin wire from the top of the canister. Place
one of the electrical access panel door screws into the red connector at
the end of the high water pin wire. WARNING – care should be taken
when performing this step as the screw is has live electricity.
3) Turn the humidifier on.
4) Touch the screw to the copper ground lug on the electrical panel for 5
seconds, the Service light should illuminate red.
5) If the Service light does not turn on remove power at the circuit breaker
and replace the current sensing board (Part Number 5530).
c. Verify fill valve operation by removing the yellow fill valve leads at the bottom of the PCB
and energizing the fill valve coil with 24VAC. If valve does not audibly click open, replace
fill valve.
10. Monitor amperage during filling and operation.
a. Amperage will increase as water level increases and as temperature in the canister rises.
When water starts to touch the electrodes, the amperage should increase slowly from 0
to approximately 5 amps. As the water in the canister heats, amperage should continue
to increase though less rapidly.
b. If canister is used, and there is no increase in amperage as the canister fills, drain the
humidifier and replace the canister.
11. Check for water outside of the canister.
a. Drain valve/canister joint – Replace drain valve O-ring (Part Number 5258).
b. Fill lines - Verify spring clamps and fill valve compression fittings are tight.
12. Check for steam leaks at the canister/steam hose joint.