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20
HE-Series Outdoor
ERV
INSTALLATION
1. Connect only to components intended for use with 24 VAC power.
2. Do not undersize the low-voltage wires connected to this device. Observe the wire length
and gauge limits indicated in this manual.
3. Do not overload this unit’s 24 VAC power supply system. Confirm that the power require-
ments of devices you connect to this power supply system do not exceed 8 VA in total.
4. If an external source of 24 VAC power is used to control the unit, consult the wiring
schematics and connect the external power only to the specified terminals in order to
avoid damaging the unit or external controls. Connect only CLASS II power to the control
terminals of this unit.
5. Unit is not equipped to receive analog signals (such as 1–10 vdc or 4–20 mA).
CAUTION
5.3.3 How to Reset the 24 VAC Circuit Breaker
If the transformer is subjected to an excessive load or a short circuit, the circuit breaker will trip
to prevent the failure of the transformer. When it trips the circuit breaker’s button pops up. Shut
off the primary-side power to the unit, and remove the excessive load or the short. The circuit
breaker can be reset about fifteen seconds after it trips by pressing in the button.
If primary-side voltage
is 230 VAC, move black
primary-side lead from
transformer’s “208 V”
terminal to the transform-
er’s terminal marked “240
V” (“230 V” in some units).
Do not move the black
primary-side lead that is
connected to the trans-
former’s “COM” terminal.
NOTICE
Be careful if the external
control system provides 24
VAC power at its control
output: make sure blue and
red leads are separately
capped and not connected
to any other wires.
CAUTION
5.3.4 Limits of Power Output
If limits on wire gauge and length are observed, you may connect control devices that draw
up to 8 VA to the blue and red wires. More than one device can be connected as long as total
steady-state load does not exceed 8 VA.
5.3.2 Low Voltage Control System
This ERV is provided with a Class II 24 VAC power supply system that operates the unit’s
contactor(s) for HE1.5XRT. The ERV’s 24 VAC Power Supply can also be used to power the
externally-installed controls system: up to 8 VA of power is available.
The unit’s power supply system includes isolation relay(s) so you can use external controls
whose contact ratings are as low as 50 mA (1.2 VA). Also, it is possible to operate the isolation
relays with 24 VAC power from an external source (with proper wiring connections).
A built-in circuit-breaker prevents damage to the transformer and other low-voltage
components in the event of a short-circuit or overload. In extreme cases, the transformer itself
is designed to fail safely.
Specifications:
u
Nominal Output Voltage under load: 24 VAC
u
Typical Output Voltage at no load: 29–31 V
u
Minimum contact rating for connected control device: 50 mA (1.2 VA)
u
Circuit Breaker Trip Point: 3 A
Wire Gauge
#22
#20
#18
#16
#14
#12
Circuit Length
100'
150'
250'
400'
700'
1000'
“Circuit Length” is distance from ERV to Control Device.
Observe these limits to wire length and gauge in order to ensure reliable operation of the
control system.
