Installation and Maintenance
EHU-600 Series Humidifiers
11
It should be mounted 6 to 10 feet downstream
from the steam dispersion tube (see Fig. 11-1). The
high limit stat must be upstream of filters, silencers,
takeoffs, etc. since these devices can reduce duct
humidity and prevent the high limit stat from doing
its job. Complete mounting instructions are contained
in the High Limit Stat package.
Figure 11-1: High Limit
Duct Humidistat
9.
Fan Interlock Switch
A fan interlock switch is recommended to deactivate the humidifier when
there is insufficient air flow in a duct system. A duct pressure switch is
preferred as a fan interlock device. The pressure switch should open
on insufficient air flow (opens on fault). See Figure 10-3 for wiring
terminals and overall wiring diagrams. Complete installation and
wiring instructions are contained in the duct pressure switch package.
Armstrong Pressure Switch: (Armstrong Part A9023) All Pressure and
electrical connections and set point adjustments are on side for each
installation. Temperature limit: 32°F. to 180°F.
Maximum surge pressure: 10 psig Rated pressure: 45" H
2
O
Pressure connections: 1/8" NPT Operating range: 0.07 to 0.15" H
2
O
Installation:
a.
Select a location that is free from excessive vibration, corrosive
atmosphere and within temperature limitations.
b.
Connect switch from pressure source with tubing (1/4" O.D.
is recommended) to high pressure port. The low pressure port
is left open to atmosphere.
Note: Above procedure is for downstream side of fan
installation. For fan suction side installation, see instructions
accompanying switch.
c.
Electrical connections to the switch are provided by means of
screw terminals marked common and normally open. The
normally open contacts close when pressure increases beyond
the set point.
d.
Complete instructions are contained in the pressure switch
package.
Note: Limit switches (high limit and fan interlock switches) open
on fault.
NOT LESS THAN 6 FEET, NOT MORE THAN 10 FEET
Air Flow
Dispersion Tube
High Limit
Humidistat
Duct
