Nu-Air Ventilation Systems Inc. - HRV Operating & Installation Manual
Rev. 2.3 Aug. 19, 2014
- 14 -
4.1.
Main Board Features
The following sections outline some of these features and explain the board in greater detail. A qualified
technician must do any service work done within the electrical panel of the HRV.
Powerful Transformer
A virtually unlimited number of ES Series controls can be connected in either series or parallel. Up to
six (6) WIN-20 Timers can be connected in parallel.
Circuit Protection
Field mis-wiring of 24 V controls, may cause the board fuse to trip. If this happens, remove the control
wires and allow fuse to reset (may take a few minutes). Check manual for proper wiring connections.
220 V/50 Hz compatibility
Factory adjusted jumper setting for 220V/50Hz geographic areas.
Variable Low- and High-Speed Motor Control
As discussed and illustrated in Section 3, speed adjustment of each motor in both low and high speed is
possible using the FRESH and EXHAUST air pushbutton switches, located on the side of the unit.
12-Volt and 24-Volt Control Options
Because the unit comes complete with a 24 V (up to 10 wires) terminal block and an additional 12 V (4-
wire) receptacle, thus your unit can be operated by a variety of control means and strategies.
Intelligent Defrost Cycles
Your unit will adjust defrost frequency and duration, based on outdoor temperature: -5º C (23º F) -15º C
(5º F), -20º C (-4º F) and -27º C (-17º F).
5
th
Port, Recirculation and Defrost.
A temperature sensor is located in the fresh air stream before the core. When the outdoor air temperature
is measured at -5º C (23º F), a timed defrost cycle is initiated. For example, at -15º C (5º F) NU145 will
run normally for approximately 37 minutes and then shut off the exhaust air fan for 6 minutes,
meanwhile closing a damper to incoming outside air. Closure of the damper allows the unit to then draw
air from a neutral space through its (top) 5
th
port and circulate this warm indoor air (not from exhausted
areas) through the heat recovery core to defrost it. Timed cycles repeat until the temperature rises above
- 5º C (23º F). Defrost has priority over all functions, i.e. commands from all remote controls will
start/resume after a defrost cycle.
Neutral Pressure Defrost, Clean Recirculation
In defrost and cycle modes, ES Series H/ERVs do not induce indoor negative pressure nor do they
recycle exhaust air; rather, they redistribute ambient room air. This feature makes your ES Series HRV
ideal for drawing air from super-heated areas, e.g. where a fireplace or woodstove operates, and
distributing this heat to other areas of the home. Consult Section 4.2 for ES recirculation controls.
Backdraft Protection
When the machine is set to
Standby
, the damper automatically closes off the fresh air port to prevent
the potential of unwanted drafts while the machine is not in operation.
