Armstrong World Industries EHU-704 Duct Mounted Control Humidistat, High Limit Duct Humidistat

Figure 11-1

1.9 - 3.9 Vdc

Voltage Source	17	Black	Part No.
		White	C1471
Ground	2
		Green
Stat In	1		or
N/C	20		C1472

Set BJ4 Stat Input Selector to 1.9 - 3.9 Vdc

Set BJ5 Voltage Source to 12 Vac

		On-Off Humidistat
Switch Opens on RH Rise
Voltage Source	17		Brown	Part No.
				A8581
Ground	2		Orange
Stat In	1			or
N/C	20			A8581A

Set BJ4 Stat Input Selector to On/Off Set BJ5 Voltage Source to +5 Vdc

4-20 mA & 0-10 Vdc Setting*

Voltage Source	17	-
Ground	2
		+
Stat In	1
N/C	20

Set BJ4 Stat Input Selector to 0-10 Vdc or 4-20 mA

0-135 Ω Ohm Potentiometer

		Part No.
Voltage Source	17	A6707A
Ground	2	or
Stat In	1	A18611
N/C	20	Humidity
		Increase

Set BJ4 Stat Input Selector to 0-135 Ohm

Set BJ5 Voltage Source to +5 Vdc

*See Figure 10-1 for Armstrong 0-10 Vdc Humidistat Connections

Duct Mounted Control Humidistat:

Duct-mounted control humidistats are also available for installation where sensing and control of return air or exhaust air ducts is preferable. (Figure 10-1)

Please refer to manufacturer's recommendations for further information on the location, mounting, and operation of the various control humidistats.

10)HIGH LIMIT DUCT HUMIDISTAT

Remove the jumpers tab from terminals 10 & 14 and wire the high limit stat between these terminals. Refer to Figure 10-1 and Figure 11-1 (the overall wiring diagram) for more information. A duct mounted high limit humidistat is recommended to prevent over-saturation of the duct air. Use an on-off controller that opens on fault (high humidity). Humidistat should be set for a maximum of 90% RH. Alternately, a modulation high limit humidistat may be used on applications such as variable air volume (VAV). Locate the high limit humidistat approximately 10' (3m) downstream of the dispersion manifold. If 10' (3m) is not available, consult the factory.

11)AIRFLOW SWITCH

An airflow switch is recommended to deactivate the humidifier when there is insufficient air flow in a duct system. A duct pressure switch is preferred as an airflow sensor. The pressure switch should open on insufficient airflow (opens on fault). Airflow switch should be mounted in supply air duct upstream of humidifier dispersion. Remove the jumper tabs between terminals 9 & 15 and wire the airflow sensor between these terminals. See Figure 11-1 and Figure 12-1 (the overall wiring diagram) for more information. Complete installation and wiring instructions are contained in the duct pressure switch package.

NOTE: LIMIT SWITCHES (HIGH LIMIT AND AIRFLOW SWITCHES) OPEN ON FAULT.

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