A Comprehensive Guide: What is a Heat Recovery Unit (HRU) & How Does it Work?

As energy efficiency and sustainability take centre stage in HVAC design, Heat Recovery Units (HRUs) are becoming essential for reducing energy costs and improving indoor air quality. By capturing and reusing thermal energy from outgoing air, HRUs minimise waste, optimise HVAC performance, and significantly lower operational costs.

At iACS, we offer tailored HRU control solutions that align with your project’s energy and ventilation needs. From design and integration to component supply, we ensure your HVAC system performs at its peak while staying environmentally responsible.

Table of Contents

1. What is a Heat Recovery Unit (HRU)?
2. How Does a Heat Recovery Unit Work?
3. Types of Heat Recovery Units
4. Key Benefits of Heat Recovery Units
5. Maintenance Tips for Heat Recovery Units
6. Environmental Impact and Sustainability
7. Applications of Heat Recovery Units
8. Why Choose iACS for HRU Services?
   
   

What is a Heat Recovery Unit (HRU)?

A Heat Recovery Unit (HRU) is a ventilation system component that transfers thermal energy between incoming and outgoing airflows. HRUs recover up to 90% of the heat from exhaust air, using it to precondition incoming fresh air. This reduces the load on HVAC systems, cutting energy costs while maintaining a constant flow of clean, temperature-regulated air.

How Does a Heat Recovery Unit Work?

HRUs utilise heat exchangers to transfer energy between two air streams without mixing them.

1. Exhaust Air Extraction: Warm, stale air is drawn from indoor spaces and directed through the HRU.
2. Energy Transfer: The heat exchanger captures thermal energy from the outgoing air.
3. Fresh Air Preconditioning: The captured energy preheats (or pre-cools) incoming fresh air, reducing the HVAC system’s workload.
4. Air Distribution: Preconditioned air is distributed throughout the building for enhanced comfort and efficiency.

With designs like plate heat exchangers, rotary heat exchangers (also known as thermal wheels), and run around systems, HRUs can be tailored to various applications, ensuring optimal performance in any setting.

Types of Heat Recovery Units

1. Rotary Heat Exchangers (Thermal Wheels)

• High-efficiency option with the ability to transfer both heat and moisture.
• Best suited for humid environments or applications requiring balanced humidity.

2. Plate Heat Exchangers

• Compact and efficient, transferring heat without allowing air streams to mix.
• Ideal for smaller commercial and residential settings.

3. Run-Around Coil Systems

• Uses a liquid medium to transfer heat between separate air streams.
• Suitable for applications requiring complete separation of airflows.

Key Benefits of Heat Recovery Units

1. Energy Efficiency

Recovering up to 90% of energy from exhaust air significantly reduces the energy required for heating or cooling.

2. Enhanced Indoor Air Quality

HRUs maintain a constant flow of fresh air while expelling contaminants, improving overall air quality.

3. Cost Savings

Reduced energy consumption translates into lower utility bills, making HRUs a cost-effective choice over time.

4. Temperature Regulation

By preconditioning incoming air, HRUs maintain consistent indoor temperatures, reducing fluctuations and enhancing occupant comfort.

Maintenance Tips for Heat Recovery Units

Proper maintenance ensures your HRU operates efficiently and has a longer lifespan. Follow these tips:

1. Clean Filters Regularly: Dust and debris can clog filters, reducing airflow and efficiency. Replace or clean filters every 3–6 months.
2. Inspect Heat Exchangers: Check for dirt or blockages in the heat exchanger to maintain optimal thermal transfer.
3. Check Seals and Connections: Ensure all seals and duct connections are intact to prevent air leaks.
4. Fan Maintenance: Clean fans to prevent dust buildup, which can strain the motor and reduce performance.
5. System Calibration: Regularly calibrate controls and sensors to ensure the HRU is operating within its design parameters.
6. Annual Professional Inspection: Schedule a professional inspection to identify potential issues early and maintain peak efficiency.
   
   

Environmental Impact and Sustainability

HRUs are not just cost-effective—they’re environmentally friendly too. Here’s how:

1. Reduced Carbon Footprint: By recycling up to 90% of thermal energy, HRUs lower the demand on heating and cooling systems, reducing greenhouse gas emissions.
2. Lower Energy Consumption: Minimising energy waste directly contributes to more sustainable energy use.
3. Support for Green Building Certifications: Installing HRUs can help meet energy-efficiency standards for certifications like BREEAM or LEED.
4. Enhanced Resource Efficiency: By reducing reliance on external energy sources, HRUs promote sustainable resource management.
   
   

Applications of Heat Recovery Units

HRUs are versatile and suitable for a range of environments:

1. Residential Spaces

Ideal for improving air quality and reducing energy costs in homes.

2. Commercial Buildings

Offices, retail stores, and hotels benefit from consistent air quality and energy savings.

3. Healthcare Facilities

Hospitals and laboratories rely on HRUs for maintaining air quality while adhering to strict energy standards.

4. Industrial Facilities

Factories and warehouses use HRUs to ensure temperature stability and air quality in large-scale operations.

Why Choose iACS for HRU Services?

At iACS, we specialise in providing customised HRU control solutions tailored to your project’s unique requirements. Here’s why we’re the trusted choice:

1. Customised HRU Design and Integration
   Our team designs and integrates HRUs seamlessly into existing or new HVAC systems, ensuring maximum efficiency.
2. High-Quality Components
   We supply premium components, from sensors to control systems, sourced from leading manufacturers like Belimo, ABB, and Carel.
3. Comprehensive Support
   From installation and commissioning to maintenance and upgrades, we offer end-to-end support for your HRU projects.
4. Sustainability Expertise
   Our solutions are designed to align with your energy-saving goals, helping you achieve both cost and environmental benefits.
   
   

Get in Contact with iACS Today

A Heat Recovery Unit (HRU) is an essential addition to any modern HVAC system, offering unparalleled energy efficiency and air quality improvements. Whether you’re upgrading your current system or planning a new installation, iACS has the expertise and solutions to make it happen.

Contact us today to learn more about our HRU services and discover how we can help optimise your HVAC system.