Aprilaire model 800 specifications Problem Possible cause Action, Drain valve, or plugged

TROUBLESHOOTING Guide (continued)

TABLE 5 – Troubleshooting Guide (continued)

Problem

Possible cause

Action

Unit does not drain	No power to drain valve	• Verify drain valve electrical connections.
	Drain fault, plugged	• Check drain valve piping.
	drain valve, or plugged
	drain pipe
	Defective drain valve	• If voltage is present at valve and it still does not open, replace valve.
Unit does not perform	Input signal always has	• Reduce demand signal.
end-of-season drain	a demand
	Drain valve	• Verify drain valve electrical connections.
		• Check for plugged strainer in bottom of canister.
Humidity below	No humidity demand	• Check for proper wiring.
desired level	signal from control
	Unit is operating but	• Increase control setting.
	fails to meet required	• Wire to 208 or 240 volts if originally on 120 V circuit.
	humidity output	• If water is siphoning from the steam canister to the overflow drain, check if there is
		excessive internal steam pressure, determine the cause of the high pressure (e..g.., high
		duct static pressure, bent or crushed steam hose) and repair as required..
		• If drain valve does not close fully, determine the cause and clean, repair, or replace as
		needed..
		• If fill valve is stuck open, repair or replace.
		• Check steam hose and connections for leaks.
	Steam canister not	• Verify that control is calling for humidity.
	heating	• Check for control voltage if limit controls (airflow proving switch, etc.) are not allowing
		unit to operate..
		• Check input power circuit.
	Water conductivity	• Add 1/10 teaspoon table salt to fill cup.
	too low
Humidity above	Improperly located	• Relocate, using guidelines described in this manual.
set point	control
	Malfunctioning controls	• Check for incorrect supply voltage.
		• Check for incorrect control signal.
		• Check for improper wiring hookup.
		• If control is malfunctioning, replace.
Hunting	Malfunctioning control	• If there is a faulty or inaccurate control, replace.
(humidity swings		• Relocate poorly located control components. See humidity control placement
above and below		information in this manual..
desired set point)
Noisy operation	Fill/drain valve noise	• A clicking sound as the fill valve opens or closes, and a hissing sound during fill
		are normal.. A slamming sound as fill valve closes is “water hammer” and can be
		minimized by installing a shock arrestor..
		• A loud buzzing sound indicates poor alignment of valve stem. Replace valve.
Water dripping	Foaming due to	• Rinse canister and steam hose in clean water.
or spitting from	impurities in canister
dispersion tube	or steam hose

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