Nu-Air NU800 HRV Review: 800 CFM Light Commercial Heat Recovery Ventilator for Large Homes and Multi‑Unit Buildings

Key Summary

The Nu-Air NU800 is a high-capacity heat recovery ventilator (HRV) designed for continuous-duty balanced ventilation in light commercial spaces, multi-unit residential projects, and large custom homes. It offers up to 800 CFM of airflow, high heat recovery effectiveness, and robust construction, but it requires careful design, substantial ductwork, and an appropriate project size to justify its cost, footprint, and installation complexity.

TL;DR

• The Nu-Air NU800 is a light commercial HRV rated around 800 CFM, suited to larger homes, multi-unit residential corridors or suites, and small commercial spaces that need balanced ventilation with heat recovery.
• Its heat recovery core captures a large share of exhaust air heat, improving comfort and reducing heating loads in cold and mixed climates, but it does not manage indoor humidity like an energy recovery ventilator (ERV).
• Continuous-duty operation is realistic if airflow is properly balanced, filters are maintained, and the unit is commissioned with appropriate fan speed settings for the duct layout and static pressure.
• Installation demands significant space for the cabinet and ducts, adequate electrical service, and good access for service; improper design can increase noise and reduce efficiency.
• For small to average homes or single suites, a smaller residential HRV will usually fit better, cost less, and be easier to install and commission than the NU800.
• Choose an HRV like the NU800 over an ERV when you prioritize heat recovery in cold climates, have relatively low indoor moisture loads, or want simpler humidity control via other systems.

Product Introduction

If you are planning a large custom home, a multi-unit residential building, or a light commercial space, the Nu-Air NU800 sits in a category that many homeowners and small building owners never encounter: light commercial heat recovery ventilation. This unit aims to bridge the gap between small residential HRVs and fully engineered commercial air handling systems, offering high airflow with relatively compact dimensions and straightforward controls. Before you commit to a system like this, it is important to understand where the NU800 shines, where it can be overkill, and how it compares with smaller residential HRVs and energy recovery ventilators (ERVs) that may also appear on your shortlist.

What Is the Nu-Air NU800 HRV and Who Is It For?

The Nu-Air NU800 is a heat recovery ventilator intended for **balanced, whole-building ventilation** in projects that sit between typical single-family homes and large commercial towers. It is classified as a light commercial HRV, meaning it can deliver higher airflow than most residential units while remaining simpler and more compact than full-scale commercial air handlers.

Target use cases include:

• Multi-unit residential corridors and common areas that need continuous fresh air without large rooftop air handlers.
• Larger custom homes or estates where a single residential HRV cannot cover the floor area and multiple smaller units would clutter the mechanical room.
• Townhouse blocks or stacked flats where one centrally located HRV serves multiple units via a shared duct system (when local codes allow).
• Light commercial spaces such as small offices, clinics, or studios that require balanced ventilation but do not need complex commercial air handlers.

In these scenarios, the NU800’s **800 CFM capacity** and balanced ventilation design can provide a single, centralized solution. But that same capacity can easily be excessive for a typical single-family home or small duplex, where a more modest residential HRV will often be easier to integrate and more cost-effective.

How Heat Recovery Ventilators Work (and Where an HRV Beats an ERV)

The NU800 is a **heat recovery ventilator**, not an energy recovery ventilator. Understanding that difference is essential before deciding whether this unit—or any HRV—is appropriate for your project.

HRV Basics: Balanced Ventilation with Heat Exchange

An HRV like the NU800 uses two fans and a heat exchanger core to provide **balanced ventilation**:

• One fan pulls in outdoor air and distributes it to living or occupied spaces.
• The other fan exhausts stale indoor air from bathrooms, kitchens (not range hoods), and utility spaces.
• Both air streams pass through a **heat recovery core**, where the outgoing air transfers most of its heat to the incoming air without mixing the two streams.

In cold-weather operation, this means incoming fresh air is pre-warmed by exhaust air, reducing the heating load on your primary HVAC system. In shoulder seasons or milder climates, the impact is smaller but still relevant for comfort and energy use.

HRV vs. ERV: When Is an HRV More Appropriate?

Energy recovery ventilators (ERVs) go one step further by exchanging some **moisture** between the exhaust and supply air streams. This can reduce dehumidification loads in humid climates and retain indoor moisture in dry winter conditions. However, ERVs are not always the best choice.

Situations where an HRV like the NU800 is generally more appropriate than an ERV include:

• Cold and very cold climates where avoiding interior moisture buildup is a high priority, especially in tight, well-insulated buildings.
• Buildings with variable or uncertain indoor moisture loads (e.g., multi-unit buildings with cooking, showers, and occupant behavior that vary from unit to unit), where moisture transfer could lead to window condensation or high humidity.
• Projects where dehumidification and humidification are handled by dedicated equipment, and you want ventilation to focus on heat recovery and fresh air supply.

If your priority is **robust winter performance, simple control of indoor humidity via other systems, and predictable behavior across multiple dwelling units**, an HRV design is often preferable. The NU800 fits this profile by focusing on sensible (heat) recovery, not latent (moisture) transfer.

Airflow Capacity and Sizing the NU800 for Real Projects

The defining feature of the NU800 is its **maximum airflow rating of roughly 800 CFM**. That number can sound abstract until you translate it into building sizes and code requirements. For context, many single-family residential HRVs operate in the 100–250 CFM range.

What 800 CFM Means in Practice

Ventilation requirements vary by code and standard (for example, ASHRAE 62.2 in the U.S.), but a rough rule of thumb for residential designs is that a typical single-family home needs somewhere between 50 and 250 CFM of continuous balanced ventilation depending on floor area, number of bedrooms, and local rules.

In real-world terms, an 800 CFM HRV like the NU800 is typically sized for:

• Large custom homes (e.g., 5,000–8,000+ square feet) where multiple floor levels and many rooms require distributed supply and exhaust grilles.
• Multi-unit residential floors where a central HRV serves multiple apartments via corridor supply and in-suite exhaust (depending on code allowances).
• Light commercial spaces such as open-plan offices, studios, or clinics with occupant densities higher than a typical home.

Most residential applications will not run the NU800 at full 800 CFM continuously. Instead, designers often select a unit with extra capacity to accommodate duct losses, filtration, and future changes, and then operate it at a lower continuous rate with boost modes when needed (for example, higher speed when occupancy increases).

Static Pressure and Duct Design

Reaching 800 CFM in the real world depends on **static pressure**—the resistance the fans must push against. Long duct runs, many elbows, undersized trunks, restrictive grilles, and high-MERV filtration all increase static pressure and reduce delivered airflow at a given fan speed.

To actually benefit from the NU800’s capacity, your designer or contractor should:

• Use appropriately sized duct trunks and branches, avoiding sharp transitions and unnecessary fittings.
• Lay out the system to minimize long, convoluted runs, especially on the exhaust side where moist air is removed.
• Account for filter resistance and any additional accessories when selecting fan speed and balancing the system.

If duct design is poor, you may find that a supposedly 800 CFM unit operates closer to half that value in practice—negating the main advantage of choosing a high-capacity HRV in the first place.

Heat Recovery Efficiency and Cold-Climate Performance

The core purpose of the NU800 is to recover a significant portion of the exhaust air’s heat and transfer it to the incoming fresh air stream. Manufacturer specifications typically express this in terms of **sensible heat recovery efficiency** or effectiveness, often in the range of 60–80% for light commercial HRVs under standard test conditions.

What to Expect from Heat Recovery

In a cold climate, if outdoor air is, for example, 10°F (−12°C) and indoor air is 70°F (21°C), a high-effectiveness HRV core might deliver supply air somewhere in the range of 50–60°F (10–16°C) before it reaches your distribution ducts. Your main heating system then raises that supply air temperature the rest of the way if needed.

You will not get indoor-temperature supply air directly out of an HRV, but you dramatically **reduce the energy penalty of ventilation**, which becomes more important as your building envelope airtightness improves.

Frost Control and Defrost Strategies

In colder climates, HRVs must manage frost buildup on the core when moist indoor exhaust air meets very cold outdoor air. The NU800, like other modern HRVs, relies on a **defrost strategy** (typically fan-speed adjustments, bypassing, or supply-air recirculation) to protect the heat exchanger at low temperatures.

Defrost cycles temporarily reduce heat recovery and may slightly shift the balance between supply and exhaust flows. For light commercial and multi-unit projects, this is rarely a deal-breaker, but it does reduce net efficiency in the coldest weather. Proper duct insulation, sealed penetrations, and good commissioning help maintain performance and prevent condensation issues around the unit and ducts.

Filtration: Protecting Occupants and the HRV Core

Filtration in an HRV serves two main purposes: protecting occupants by reducing particulate matter and protecting the **heat recovery core and fans** from dust and debris. The NU800’s filtration strategy, like similar units, usually includes filters on both the outdoor-air intake and the exhaust airstream to minimize dirt accumulation on the core surfaces.

Filter Types and Maintenance

While specific filter ratings depend on how the system is configured and what optional filters are installed, you can expect something in the **MERV 8–13 range** for general-purpose particulate control. Higher-MERV filters improve fine-particle removal (pollen, fine dust, some smoke), but they also create more static pressure, which can reduce airflow and increase fan energy use if not accounted for in design.

In a light commercial or multi-unit context, filters must be **inspected and replaced regularly**, especially in urban locations or near busy roads where outdoor air may carry more particulates. The NU800’s suitability for continuous-duty operation hinges on the building operator’s willingness to follow a maintenance schedule—neglecting filters can quickly reduce performance and raise operating costs.

Filter Access and Serviceability

From a homeowner or facility manager’s perspective, it is important that filters are **easy to access**. With light commercial equipment such as the NU800, this typically means a front or side access panel that can be opened without dismantling ductwork. When planning installation, leave ample clearance around the unit for filter changes and inspection of the core, fans, and condensate management components.

Noise Expectations: How Quiet Is the NU800 in Real Use?

Noise is a common concern for both large homes and light commercial spaces. An 800 CFM HRV has larger fans than a 150 CFM residential unit, so **proper isolation and duct design** are essential to achieving quiet operation.

Unit Noise vs. Duct-Borne Noise

There are two main noise sources to consider:

• Mechanical noise at the unit itself (fan motors, air turbulence inside the cabinet).
• Air noise in the ducts and at grilles (air rushing through undersized ducts, fittings, and registers).

Light commercial HRVs like the NU800 are generally engineered with **insulated cabinets** and balanced fans to keep mechanical noise in check. In practice, overall sound levels at occupied zones depend more on the duct system design than on the cabinet itself. Long straight runs, appropriately sized ducts, and the use of flexible connectors or short sections of acoustic duct near the unit all help.

Locating the Unit for Comfort

For large homes and multi-unit projects, installing the NU800 in a **dedicated mechanical room** or service area away from bedrooms and quiet spaces is best. The further the unit is from sensitive areas—and the more structure and insulation between—the easier it is to maintain low noise levels. Ceiling or rooftop mounting is sometimes possible in light commercial spaces but may increase structural transmission unless vibration isolation is used.

Continuous-Duty Operation and Reliability

Modern HRVs are typically designed for **continuous-duty** operation, meaning they can run 24/7 at a selected speed. For light commercial and multi-unit buildings, this is often the default strategy to maintain indoor air quality. The NU800’s fan motors, core, and cabinet are built with this type of operation in mind.

Duty Cycle and Control Strategies

Common operating strategies for the NU800 include:

• Continuous low- or medium-speed operation to maintain baseline fresh air in all occupied zones.
• Boost modes triggered by occupancy schedules, CO₂ sensors, or switches in high-use areas like gyms or conference rooms.
• Night setback or reduced speed when the building is unoccupied (for light commercial applications).

Running constantly at maximum capacity is rarely necessary and often not recommended. Instead, a correctly sized NU800 will spend most of its life at partial load, which can improve fan life, reduce noise, and lower energy use while still delivering the required ventilation.

Expected Lifespan and Maintenance

The longevity of the NU800 depends mainly on **installation quality and maintenance** rather than the nameplate itself. Reasonable expectations in a light commercial or multi-unit context—assuming proper care—are:

• Fans: many years of service, with occasional bearing or motor replacements over the life of the building.
• Heat recovery core: long service life if protected from dust and mechanical damage; cleaning may be required periodically.
• Cabinet and controls: generally durable, though exposure to moisture, corrosive air, or physical damage will shorten life.

A maintenance plan should include **regular filter changes, occasional inspection of the condensate drain, checking ducts and grilles for blockages, and verifying fan operation**. With these basics in place, an NU800 can provide reliable, low-drift performance for many years.

Installation Considerations for the Nu-Air NU800 HRV

An 800 CFM light commercial HRV does not install like a compact residential unit. Getting good performance from the NU800 depends heavily on good design choices around **ducting, electrical, space planning, and commissioning**. These considerations are particularly important in retrofit projects and high-performance new builds where space and airtightness are carefully planned.

Ducting Requirements and Layout

Proper duct design is central to the NU800’s success. Key points include:

• Use large-enough supply and exhaust trunks to avoid high air velocities and noise; designers often use sheet metal ducts for main trunks in light commercial applications.
• Balance supply diffusers and exhaust grilles across the building to achieve even ventilation. Avoid clustering too many takeoffs close to the unit unless the design accounts for pressure imbalances.
• Insulate ducts running through unconditioned space, especially outdoor air and exhaust runs, to reduce condensation and energy loss.

Where possible, keep outdoor-air intake and exhaust outlets separated on the building exterior to avoid recirculating exhaust air. For multi-unit and large-home projects, this often means planning penetrations early in design to keep runs short and maintain a neat façade.

Electrical Needs and Controls Integration

The NU800 requires a dedicated electrical circuit sized to match its voltage and amperage requirements, similar to other light commercial mechanical equipment. In many projects, the HRV is integrated with building controls via low-voltage communication lines, occupancy sensors, or scheduling systems.

For large homes, the HRV may be connected to simple wall controls, programmable timers, or indoor air quality sensors (such as CO₂ or VOC monitors). In light commercial spaces or multi-unit buildings, integration with a building automation system (BAS) may be desirable for **remote monitoring, fault detection, and scheduling**.

Space Planning and Access

Physically, the NU800 is larger and heavier than residential HRVs. Mechanical rooms must be planned to accommodate:

• Clearance on service sides for filter changes, core removal, and fan inspections.
• Structural support for the unit’s weight, especially for wall-hung or ceiling-hung installations.
• Room for duct transitions, elbows, and connections without cramming fittings too close to the cabinet, which can cause turbulence and noise.

In multi-unit residential or commercial retrofits, it is common for mechanical rooms to feel tight. Early coordination between the architect, mechanical designer, and installers is critical to prevent rerouting ducts later or compromising airflow due to space constraints.

Commissioning: Balancing Airflows and Verifying Performance

Commissioning is where the NU800’s potential either becomes reality or falls short. Proper commissioning includes:

• Measuring supply and exhaust airflows at the unit and at representative grilles using flow hoods, anemometers, or balancing devices.
• Adjusting balancing dampers so that overall supply and exhaust flows are **as close to equal as possible**, maintaining true balanced ventilation.
• Verifying temperature rise across the heat recovery core to ensure it is performing within expected ranges under design conditions.
• Checking defrost operation, condensate drainage, and control logic (such as boosts, schedules, or sensor triggers).

Skipping or rushing commissioning can lead to uneven room ventilation, pressure imbalances, drafts, and poor energy performance—issues that occupants often blame on the unit itself rather than on installation and setup.

Practical Limitations: Size, Cost, and Complexity

Although the NU800 offers substantial ventilation capacity and robust performance, it is not the right fit for every project. Its **size, cost, and installation complexity** all point toward larger or more intensively used buildings.

Equipment and Installation Cost

Compared with compact residential HRVs, an 800 CFM light commercial unit like the NU800 involves higher upfront equipment cost and greater installation labor. More extensive ductwork, larger penetrations, and potentially higher electrical and control integration costs all add up.

For large custom homes or multi-unit projects, these costs can be justified by the need for higher airflow and centralized control. For smaller homes, the same budget may deliver better overall value through properly sized residential HRVs, upgraded filtration, and envelope improvements instead of oversizing the ventilation equipment.

Physical Footprint and Weight

The NU800’s cabinet and associated duct trunks require more space than a residential HRV. In new construction this can be addressed through early planning, but in existing buildings, finding a suitable installation location can be challenging. Units of this class may also require multiple installers or lifting equipment to move into mechanical spaces safely.

When a Smaller Residential HRV Is a Better Fit

For many single-family homes and small duplexes or triplexes, a **smaller residential HRV** will provide all the airflow needed with a more compact footprint, lower cost, and simpler installation. Indicators that a residential HRV may be more appropriate include:

• Total floor area under roughly 3,500–4,000 square feet with typical occupancy and standard-code ventilation needs.
• A desire to tuck the HRV into a smaller mechanical closet or ceiling space without dedicating a full mechanical room.
• Limited budget for mechanical systems, where money is better spent on better windows, insulation, or heating/cooling upgrades.

In such cases, a well-chosen residential HRV—properly installed, balanced, and maintained—can meet ventilation goals without the extra capacity and complexity of an 800 CFM light commercial unit.

HRV vs. ERV: Climate and Use-Case Scenarios

Because the NU800 is an HRV, not an ERV, it is worth taking a closer look at **climate and occupancy patterns** to judge whether this is the right type of unit for your building. While the NU800 excels at sensible heat recovery, it does not directly moderate indoor humidity by transferring moisture between air streams.

Cold and Mixed Climates

In cold and mixed climates with significant heating seasons, HRVs are popular because they help prevent excessive indoor humidity that can lead to **condensation on windows and cold surfaces**, mold growth, and damage to finishes. The NU800 is well-suited to such climates when used in airtight, well-insulated multi-unit buildings and large homes where moisture loads from cooking, showers, and occupants add up quickly.

Humid and Hot Climates

In more humid climates—especially where cooling dominates—an ERV can sometimes be advantageous because it helps limit how much outdoor humidity enters the building with ventilation air. That said, ERVs are not a cure-all for humidity problems and are often used alongside mechanical dehumidification.

If you are planning a project in a hot, humid region and are considering the NU800, discuss with your mechanical designer whether **dedicated dehumidification, an ERV alternative, or a hybrid strategy** might be more appropriate. In many cases, though, large multi-unit buildings rely on HRVs and building-wide HVAC systems to manage humidity rather than ERVs alone.

Variable Occupancy and Multi-Unit Use

In multi-unit residential buildings, occupancy patterns can change frequently, and moisture production is unpredictable. Some suites will have frequent cooking and showers, while others may sit partly vacant. For these reasons, many designers prefer **HRVs for central systems** in such buildings because they offer consistent behavior regardless of indoor moisture variations. The NU800 aligns with this approach by focusing on reliable, balanced airflow and heat recovery.

Is the Nu-Air NU800 Right for Your Project?

Deciding whether the NU800 is appropriate comes down to matching its **capacity, configuration, and type (HRV) to your building’s needs**. It delivers significant benefits in the right scenarios but may be excessive in others.

Best-Fit Scenarios

The NU800 tends to be a strong fit when:

• You are designing a large custom home, multi-unit residential building, or light commercial space where ventilation needs exceed what a single residential HRV can deliver.
• You want **centralized balanced ventilation** with heat recovery rather than multiple small point-source fans or distributed HRVs in each unit.
• You are in a cold or mixed climate where sensible heat recovery is a priority, and you are managing humidity via other systems or through building design.
• You have access to qualified contractors who can design the ductwork, electrical, and controls properly and commission the system thoroughly.

Situations Where You Might Choose a Different Solution

You may want to explore a different ventilation approach if:

• Your home is modest in size, and the calculated ventilation requirements fall within the range of residential HRVs.
• You primarily need **moisture control in a humid climate**, where an ERV combined with humidity-focused design may provide better comfort.
• Your renovation has limited space for new ducts and mechanical equipment, making large, centralized solutions impractical.
• Your project budget cannot support the combined cost of an 800 CFM HRV plus the ducting, electrical work, and commissioning needed to use it effectively.

In these cases, smaller HRVs, ERVs, or even upgraded exhaust-only strategies with make-up air (where allowed by code) may better match your constraints, even if they offer less comprehensive heat recovery.

How the Nu-Air NU800 Compares With Smaller Residential HRVs

To put the NU800 in context, it helps to understand what you gain—and what you give up—compared with typical **residential HRVs** you might install in a single-family home or small duplex.

Advantages of the NU800

Against residential units, the NU800 typically offers:

• Much higher airflow capacity (up to roughly 800 CFM) for large buildings or higher ventilation rates.
• More robust components suitable for light commercial duty cycles, including larger fans and sturdier cabinets.
• Better suitability for integration with building-level controls and sensors across multiple zones or units.

If you operate a large building or want a **single, centralized ventilation solution**, these advantages can simplify overall system design.

Advantages of Smaller Residential HRVs

On the other hand, residential HRVs usually provide:

• Smaller size and lower weight, making them easier to locate in compact mechanical spaces or closets.
• Lower equipment and installation costs, with less extensive ductwork and simpler electrical needs.
• Simpler control interfaces suited to homeowners, rather than facility managers or building engineers.

For many homeowners, these practical advantages outweigh the benefits of light commercial equipment. A well-chosen residential HRV can still deliver **balanced ventilation and effective heat recovery** when properly sized to the building.

Practical Tips if You Are Considering the Nu-Air NU800

If the NU800 is on your shortlist, a few practical steps can help you make a well-informed decision:

• Work with a qualified mechanical designer or engineer who can calculate your building’s ventilation needs and determine whether 800 CFM is necessary or whether a smaller option would suffice.
• Ask for a duct layout and equipment schedule early in design so you understand space, cost, and coordination requirements before construction starts.
• Clarify whether an HRV or ERV strategy is better for your climate and use case; if humidity is a major concern, explore complementary humidity control systems.
• Ensure your contractor includes commissioning and balancing in the scope of work, not just equipment installation.
• Plan a maintenance routine that includes filter changes, inspections, and periodic performance checks to preserve efficiency and air quality.

These steps apply broadly to any high-capacity HRV, but they are especially important for light commercial units like the NU800, where mis-sizing or poor installation can compromise both comfort and efficiency.

Summary: A Capable Light Commercial HRV for the Right Projects

The Nu-Air NU800 800 CFM Light Commercial Heat Recovery Ventilator is best understood as a **specialized tool**: powerful and effective when matched to the right building and the right design team, but not a one-size-fits-all solution. It provides high airflow, meaningful heat recovery, and continuous-duty performance suitable for multi-unit residential and light commercial projects, as well as large custom homes with higher-than-average ventilation demands.

For typical single-family houses and modest renovations, a smaller residential HRV usually offers a better balance of size, cost, and simplicity. For larger and more complex projects, though, the NU800 can be a solid foundation for a centralized, balanced ventilation strategy—as long as you are prepared to support it with thoughtful design, careful installation, commissioning, and ongoing maintenance.

Sources

• Nu-Air — Manufacturer literature and technical documentation for light commercial HRV systems https://www.nu-airventilation.com
• ASHRAE — Ventilation standards and guidance for residential and light commercial buildings (ASHRAE 62 series) https://www.ashrae.org
• U.S. Department of Energy — Heat recovery ventilation basics and residential ventilation strategies https://www.energy.gov
• Natural Resources Canada — Guidance on HRVs, ERVs, and balanced ventilation in cold climates https://www.nrcan.gc.ca
• Building Science Corporation — Building science insights on moisture, ventilation, and HRV/ERV selection https://buildingscience.com