Nu-Air Ventilation Systems Inc. - HRV Operating & Installation Manual
Rev. 3.4 Sept. 20, 2011 - 15 -
4.1. Main Board Features
• Powerful transformer – an almost 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.
• Self-resetting fuse to protect the board against mis-wiring.
• Variable low and high speed control – each motor and both speeds may be adjusted individually
to ensure optimal ventilation rate, with minimal energy usage.
• Proportional defrost automatically adjusts defrost times and frequency according to outdoor
temperature.
• Furnace Interlock Options: Interlock in high and low speeds (default) or high speed only—
Sections 4.4, 10.2.
• Factory adjusted jumper setting for 220V/50Hz geographic areas.
• Jumper settings for various defrost and recirculation profiles.
The following sections outline some of these features and explain the board in greater detail. In most
applications, the factory settings for speed control, defrost, electrical service and fan/motor type will
never need to be changed. A qualified technician must do any service work done within the electrical
panel of the HRV.
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 ES Series comes complete with both a 12V (4-wire) and a 24V (up to 10 wires) terminal
block, your ES Series unit can be controlled by a variety of control means and strategies.
Self-Resetting Fuse
Field mis-wiring of controls, timers or dehumidistats may cause the fuse to trip. If this happens, remove
the control wires and allow the fuse to reset. This may take a few minutes. Check your manual for
proper wiring connections.
Defrost Cycles
The versatile ES Series main board is equipped with an array of jumpers which enable its use in a wide
range of machine types and allow for field modification if desired. Unless you request otherwise, your
ES Series model will arrive with optimal factory settings. For a typical ES Series model, the defrost
mechanism is described below.
5
th
Port, Recirculation Defrost.
On the ES100 & ES170 a temperature sensor is located in the fresh air stream before the core. When the
outdoor air temperature is measured below -5º C, a timed defrost cycle is initiated which will vary in
both frequency and duration at -10º C, -15º C and -20º C. For example, at -20º C, or lower the ES170
will run normally for 36 minutes and then shut off the exhaust air fan for 4 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. Defrost has
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