Nu-Air Windsor NU145 - User Manual

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Summary

System Function and Operating Tips

Installation

Installation Supplies

Lists items included with the HRV for installation.

Installer Responsibilities

Outlines duties and precautions for installers.

Installation System Options

Describes different methods for connecting the HRV.

Ducting to the Outside

Details outdoor duct installation and weather hood placement.

Mounting and Noise Control

Instructions for hanging the unit and minimizing noise.

Ductwork Guidelines

Guidelines for designing and installing duct systems.

Condensate Drain Connections

Steps for installing the condensate drain assembly.

Furnace Interlock

Explains how to interlock the HRV with the furnace.

Balancing Air Flows

Procedures for balancing air flow using measurement devices.

Adjusting Fan Speed for Balancing

How to adjust fan speeds for balancing and system needs.

Control Options and Wiring

ES Series Controls (12 VDC)

Details the ES Series controls and their functions.

ES Tx and Mx Controls

Explains the ES Tx and Mx control units.

ES Lumina Control

Features and functions of the ES Lumina control.

Windsor Series & 24 V Controls

Covers Windsor Series and other 24 VAC control options.

Wiring Windsor & 24 VAC Options

Guidance on wiring Windsor Series and 24 VAC controls.

DSTAT-1 Control

Wiring and operation of the DSTAT-1 control.

Win-1 Control

Wiring and operation of the Win-1 control.

Win-20 Control

Wiring and operation of the Win-20 control.

Remote 2-Wire Switching

Instructions for remote 2-wire switching setup.

Status LEDs and Operation Modes

Explains the meaning of status LEDs and operational modes.

Electrical Schematics

The Nu-Air Windsor Series Heat Recovery Ventilator (HRV) is a balanced central ventilation system designed to bring fresh, filtered outdoor air into your home while exhausting an equal amount of stale, humid indoor air. This process helps to maintain indoor air quality by removing odors, excessive moisture, and volatile organic compounds (VOCs) from paints, cleaners, furniture, and building materials, effectively acting as the "lungs" of your home. The system is designed for residential applications and can be installed as an independent system or integrated with a central heating/cooling system.

Function Description

The HRV operates by utilizing powerful centrifugal blowers to draw fresh air from outside and exhaust stale air from inside. The incoming fresh air is filtered before passing through a heat exchange core. Simultaneously, stale, humid air from the home flows through the same cross-flow heat exchanger, transferring its energy to the incoming fresh air without the two air streams mixing. This tempered fresh air is then distributed throughout the house via an independent or shared (furnace) duct system.

The unit is capable of several operating modes, depending on the type of controls installed:

Standby: The unit is idle but can be activated to high speed by external controls such as a timer, dehumidistat, or CO2 sensor.
Full-Time Low Speed: The unit continuously operates at a low speed and will switch to high speed when commanded by other system controls.
Full-Time High Speed: The unit runs continuously at high speed, typically activated by a central control or timer.
Timed High Speed: Timers can operate the unit at high speed for set intervals (e.g., 20, 40, or 60 minutes).
20 Lo/40 Standby: The unit cycles between 20 minutes of low-speed operation and 40 minutes of standby.
20 Lo/40 Recirculation: The unit cycles between 20 minutes of low-speed operation and 40 minutes of recirculating air within the home.
Full-Time Recirculation: The unit continuously recirculates air within the home, providing air filtration and preventing stagnant air without ventilating.

It is generally recommended to run the unit on low speed continuously to ensure a steady supply of fresh air and removal of indoor pollutants. The amount and frequency of ventilation needed can vary based on factors such as the number of inhabitants, cooking habits, hobbies, presence of pets, and whether windows are opened. Signs like moisture on windows, lingering odors, or a sensation of stuffy air indicate a need for more or increased ventilation.

Some controls include a dehumidistat (d-stat) to monitor ambient relative humidity (RH) with selectable settings (30%-80% RH). If the ambient humidity exceeds the setpoint, the ventilator will switch to high speed until the RH returns to the setpoint. While not a dehumidifier, the HRV can help reduce indoor humidity by exhausting high-RH air, especially in cooler seasons when outdoor humidity is lower. Typical dehumidistat settings are 40%-60% for winter, 50%-60% for spring/fall, and 65%-80% or OFF for summer (for non-air-conditioned homes).

Usage Features

The Nu-Air HRV is designed for ease of installation and operation. It comes equipped with filters, anti-vibration straps, a heat recovery core, and a drain hose assembly. Balancing dampers are not required, as the ES Series HRVs allow installers to adjust each motor's speed for both high and low settings. The unit includes removable terminal blocks for timers, remote controls, and furnace interlock, with specific blocks for 12 VDC ES Series controls and 24 V controls.

Installation options include:

Fully Ducted System: Uses an independent duct system for supply and exhaust air, with the HRV controlled independently. Vents are typically located in the ceiling or high on interior walls, deep within rooms, to prevent short-circuiting or drafts.
Extended Exhaust System: The HRV supply air is introduced into the return duct of a forced-air furnace, with separate ductwork for stale air from wet rooms.
Extended System, Continuous Ventilation: Similar to the extended exhaust system, but the furnace fan may not need to run continuously. For improved air distribution, the furnace can be interlocked with the HRV.
Extended System, Intermittent Ventilation: For intermittent HRV operation, the furnace fan should be interlocked with the HRV to ensure good supply air distribution during high-speed ventilation.
Simplified System: Uses the furnace's return plenum for both supply air distribution and exhaust air collection. The exhaust air connection must be sufficiently upstream of the supply air connection to prevent short-circuiting. For proper air distribution, the furnace fan must run during ventilation mode, and the furnace should be interlocked with the HRV.

For optimal performance and energy efficiency, fully insulated ducting with an integrated vapor barrier must be used between weather hoods and the HRV, and on all runs passing through unheated areas, to prevent condensation and energy losses. Weather hoods should be located with a minimum of 6 feet separation between fresh air and exhaust hoods, and at least 18 inches above ground level for supply hoods and 4 inches for exhaust hoods. They should also be at least 3 feet away from any other appliance exhaust vent or furnace vent.

The HRV is designed to be hung from the ceiling using anti-vibration straps, which are adjustable for easy mounting and leveling. It is recommended to avoid hanging the unit directly below bedrooms or other quiet areas.

Balancing air flows is crucial for HRV performance. The Windsor Series allows quick and simple motor speed adjustments using two recessed buttons. A magnehelic gauge or differential pressure digital manometer is recommended for measuring airflow. To balance, activate high speed (e.g., via remote control or jumper wire), then press and hold either the FRESH air or EXHAUST air pushbuttons for 3 seconds to enter SPEED ADJUST MODE. Each press of the corresponding button reduces motor speed until the minimum is reached, then returns to peak speed. After adjusting, stop pressing buttons for 10 seconds to save the new speeds. Low-speed adjustment follows a similar procedure.

The unit supports various remote control options, including humidity sensing, off-on control, intermittent and continuous modes, and recirculation. Both ES Series (12 VDC) and Windsor Series (24 VAC) controls can be used, though only one type of central control should be employed per installation. ES Series controls feature a touch pad and LEDs to select modes and indicate operation. The ES Lumina control offers a backlit LCD screen, navigation keys, an intuitive interface, an on-board humidity sensor, a built-in timer, and filter alerts.

Maintenance Features

Regular maintenance is essential for the longevity and efficiency of the Nu-Air HRV. Before any servicing, the power to the unit must be disconnected.

Key maintenance tasks include:

Filters: Dirty filters can reduce ventilation efficiency and damage motors. They should be vacuumed every three months. Polyester filters typically need replacement every 1-3 years and are easily accessed by opening the front cover of the unit.
Fans: When cleaning filters, vacuum any interior surfaces, including fan blades. The fans are designed for continuous operation and do not require lubrication.
Condensate Drain: The condensate drain pan should be wiped clean twice a year. The drain and tubing must be checked to ensure they are free-flowing, and the tubing should maintain an "S" or loop trap to prevent air from entering the HRV.
Heat/Energy Recovery Core: The core, located behind the cover, should be removed and cleaned at least once a year using a mild detergent in cold water. Fiber-media ERV cores should be vacuumed, not washed. The cover can be removed by unlatching two latches and sliding the door to the right.
Exterior Hoods: Outside vents should be regularly checked and cleaned of obstructions like grass, leaves, or debris. The bird screen should not be replaced with mesh smaller than 1/4 inch, as this restricts airflow. During winter, ensure snow and frost do not block openings.
Grills & Duct Work: Grills should be cleaned with soap and water when dusty or greasy. The insulation jacket on fresh air and exhaust air ducts should be checked for punctures, which should be repaired with foil tape.

Annual general servicing by an accredited contractor is recommended. This servicing should include all the above maintenance items, a general check for proper operation, and inspection of controls and electrical connections. It also involves verifying that intake and exhaust air flows are properly balanced and re-balancing if necessary.

Troubleshooting guidance is provided for common issues such as low or high humidity, frosting, cool supply air, water in the HRV, and poor airflow, with recommended solutions ranging from balancing airflows and adjusting controls to cleaning components and checking connections. Only qualified technicians should service controls or internal components.