Aprilaire Comprehensive Humidifier Troubleshooting and Error Code Solutions

MANUAL MODE OPERATION NOTES

The Automatic Steam Humidifier Control is installed in the return duct. When installed in the Manual Mode, the Control provides specific set-point control. If the building is not designed to handle the amount of RH the humidifier is supplying, the RH setting on the Control may need to be adjusted to a lower value

during extreme days to
		FIGURE 13
prevent condensation on
interior surfaces. For example,
with an outdoor temperature										55
								F		%
of 20°F the correct setting will							°
						0				T
					E	4			%
				R						R ES
			U					5		E	T
										S	/
be 35% relative humidity. If		T						4		E
											T
		A							Y
the temperature is expected to	R							T
	E
	P							I
	M	F				%		D
fall to 0°, then reduce the		°						I
	E	0				5	M
	T	2				3	U
setting to 25% several hours	R							H
	O							%
prior to the temperature	O
		D					2				F
		T
			U							F
change. It is important to								5		O
					O	0			%
						°
adjust the RH setting upward						F				15%
when the outdoor temperature									MANUAL MODE
goes back up again.											90-904

The recommended settings on the humidistat are based on years of research for an average building. (See ASHRAE Handbook – HVAC Systems and Equipment, Ch. 20 – Humidifiers.) Note: these settings may not be appropriate for every application. These settings represent a compromise between RH levels that would be most desirable for comfort reasons and humidity levels that are suitable for protection of the conditioned space and to avoid condensation on windows and within walls. For example, a wintertime indoor RH of 50% may be considered ideal for comfort, but unfortunately, it probably would result in damage to the conditioned space. Observance of the recommended RH levels on the humidistat, therefore, is an important safeguard. Condensation of water on inside windows in the form of fogging or frost is an indication of too much relative humidity. This same condensation can occur in other areas of the conditioned space with the possibility of damage resulting.

TABLE 3: Outdoor–Indoor Relative Humidity

Outside Temperature	Recommended RH
+40˚F	45%
+30˚F	40%
+20˚F	35%
+10˚F	30%
0˚F	25%
-10˚F	20%
-20˚F	15%

TROUBLESHOOTING GUIDE

Applies to both Automatic and Manual Operation unless indicated otherwise.

SYMPTOM TROUBLESHOOTING PROCEDURE

Humidifier does not operate in “Test” mode

•Make sure equipment blower is operating and thermostat is calling for heat.

•Make sure the Outdoor Temperature Sensor is connected to the “ODT” terminals of the control. (For Manual Operation, make sure Manual Mode Resistor Case is in place of the Sensor).

•Check main wiring diagram for correct Automatic Steam Humidifier Control installation.

•Check voltage at Automatic Steam Humidifier Control “24V” and “C” terminals. Voltage should be 22 VDC minimum – 26 VDC maximum.

•In “Test” mode, humidifier will operate for 1 minute only. DO NOT LEAVE IN TEST MODE AS HUMIDIFIER WILL NOT OPERATE.

•Make sure water supply valve is open.

•If humidifier still does not operate, refer to the Aprilaire Steam Humidifier Installation, Operation, and Maintenance Manual.

Humidifier operates only	• If outdoor temperature is greater than 60°F or less than -30°F, the Automatic Steam
in “Test” mode	Humidifier Control will only operate in the “Test” mode. (Automatic Mode Only)
	• If the humidity level in the building is higher than the knob setting or the proportional
	control band (Model 1160 and 1180 only), the Automatic Steam Humidifier Control will not
	operate the Humidifier.
	• Check the resistance of the sensor by removing the leads of the Outdoor Temperature
	Sensor from the terminals and measuring the resistance across the wires with an
	ohmmeter. Confirm reading to outdoor temperature in Table 4. (For Manual Operation,
	remove leads and verify that resistance across the leads of Manual Mode Resistor Case
	is between 44,000 and 48,000 ohms).
	• Make sure the Outdoor Temperature Sensor is mounted completely outside the building on the
	North, East, or West side of the building and out of direct sunlight. (Automatic Mode Only)
	• If Outdoor Temperature Sensor is mounted in fresh air intake duct, make sure the probe is
	no more than 36 inches from the outside wall. (Automatic Mode Only)
	• Make sure the Outdoor Temperature Sensor is located at least 3 feet away from all
	exhaust vents. (Automatic Mode Only)

TABLE 4

Outdoor	Resistance
Temperature	kΩ
-30˚F	230.6
-20˚F	163.8
-10˚F	117.6
0˚F	85.4
10˚F	62.6
20˚F	46.3
30˚F	34.6
40˚F	26.1
50˚F	19.9
60˚F	15.3
70˚F	11.9
80˚F	9.4
90˚F	7.4
100˚F	5.9

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