Ideally, the HRV mechanism is governed by the principle of the second law of thermodynamics. However, to achieve this, there are heat recovery ventilator parts that working together for optimal air flow and efficient heat transfer.
Let’s explore some of the main components of HRV.
What is a Heat Recovery Ventilator (HRV)?
Heat recovery ventilator is an assembly of different parts that allow for free heat and air stream flow. They not only ensure rooms have fresh, clean and quality air, but also result in significant energy savings.
Key Parts of Heat Recovery Ventilator
Some of the key parts you will find in most heat recovery ventilators include:
1. Steel Housing
The steel housing encloses all the components of heat recovery ventilator. Remember, whether you install HRV in mechanical rooms or attics, all the internal components must be safe and secure from external environment.
2. Fans (Supply and Exhaust fans)
Most HRVs have two fans that have been engineered and designed to work in tandem. Usually, the design of the supply fan and exhaust fan is such that they are carefully balanced.
This balance ensures that you don’t experience any pressurizing or depressurizing effects.
Fundamentally, the main role of exhaust air is to push stale air out of the enclosed system. At the same time, supply fan directs fresh air into the rooms.
3. Filters
Another key part of HRV is the filters. These filters are strategically positioned to clean the air stream. They will remove impurities such as dust and pollen from the air keeping the fans and heat exchangers clean.
Most modern heat recovery ventilators use high efficiency particulate air filters (HEPA filters). The main advantages of HEPA filters are that they capture 99.97% of particles that are airborne.
4. Heat Exchanger
Heat exchange is a critical HRV component. In most cases, they come across-flow cores that are designed from high performance plastic and aluminum. The heat exchange not only allows for free flow of air but also optimizes heat energy transfer.
It provides an increased surface area where the incoming and exhaust air pass near each other without mixing. This allows for optimal heat transfer.
5. Ventilation Ducts
These ducts deliver fresh air and remove stale air from rooms. In most cases, they are pre-insulated and flexible ducts with rigid options available.
At the same time, they connect the HRV unit to the inside or the outside of the house.
6. Drain Pipe
It is used to carry away any moisture that would accumulate during heat transfer. The moisture is removed when hot humid air cools down in the heat exchanger in cool weather.
7. Controls
These are timers or switches alongside humidity sensors. With these control systems, you can control various parameters of the HRV including ventilation rate or fan speed. In the modern HRV system, these systems are well integrated to work automatically.
It also has electronic boards, which allow for seamless control. This also includes other critical components like transformers that ensure HRV receives the right voltage.
8. Dampers
It helps control the air flow in the duct systems connected to the main HRV core. They open and close to control and balance flow of air to different rooms.
Other heat recovery ventilator parts in addition to the above, include:
| Components of HRV | Components |
| Core casing | · Directly houses the heat exchanger core while ensuring there is no cross-contamination between incoming and outgoing airstreams |
| Louvers/wall caps | · Prevents pest and water ingress while connecting the HRV to outside environment |
| Vibration isolator | · Prevents fan and HRV systems from excess vibration |
| Thermal bypass damper | · Suitable for extremely cold environments, thereby acting as an automatic damper |
| Electrical disconnect | · A safety electrical system allowing for safe maintenance |
Conclusion
Heat recovery ventilators are an efficient method of cooling and heating houses. The air flow is typically designed to move fresh air to clean spaces like bedrooms and living rooms first. The air then flows to rooms where it is exhausted because of odors such as bathrooms and kitchens. All these are possible with the help of the seven components we have listed above.
FAQs
What are the benefits of HRV?
It is versatile equipment that you can install in virtually all rooms to remove contaminated air, while supplying fresh air. Therefore, it improves air quality and ensures energy efficiency.
How does HRV work?
Through energy recovery technology, it uses balances airflow to expel stale and supply fresh air into rooms or space. At the same time, it allows for efficient heat transfer into the room, through the heat exchanger system.
How to determine if the filter of the HRV system needs to be replaced?
It can be done in three ways: ① Observe the color of the filter. If it becomes dark due to accumulated dust, it needs to be replaced. ② Feel that the air volume from the outlet has significantly decreased.③ Some models will light up to indicate. Generally, it is recommended to check once every 3 to 6 months.
What consequences will there be if the vibration isolator is not installed?
If the vibration isolator is not installed, the vibration generated during the operation of the fan will directly be transmitted to the steel casing and the duct, resulting in low-frequency buzzing sounds. Long-term vibration can also lead to loose screws, cracked pipe interfaces, and short-circuits in the circuit boards, thereby shortening the lifespan of the equipment.
What is the use of the thermal bypass damper in extremely cold regions?
When the outdoor temperature drops below -15°C, the internal part of the ordinary heat exchange core may freeze and become clogged. The thermal bypass damper automatically opens, allowing a small amount of cold air to bypass the heat exchange core and directly enter the room. At the same time, it increases the air flow on the exhaust side to help defrost. After the core temperature rises, the damper is closed.
Which is better, the aluminum heat exchange core or the plastic core?
Aluminum has a higher thermal conductivity, and the heat recovery efficiency can be increased by 2% to 5%. However, it has a high cost and is easy to frosting in humid and cold environments. High-performance plastic has slightly lower thermal conductivity but is corrosion-resistant, lightweight, and it does not frost.
Does the HRV drainage pipe also drain water in summer?
Yes. When the indoor air conditioner is cooling in summer, the hot and humid air passes through the heat exchange core and is cooled, which will also produce condensation water. Additionally, when the high-humidity outdoor air is pre-cooled, moisture is also produced. Therefore, the drainage pipe has the potential to drain water throughout the year.
Why is an electrical disconnect switch needed inside the HRV?
The electrical disconnect switch is located outside or near the HRV casing. It is used to completely cut off the power supply during maintenance, cleaning of the filter, and inspection of the fan to prevent accidental electric shock. It is a mandatory safety device as required by national electrical standards. If it does not have this function, it must be installed by a professional electrician, otherwise there are serious security risks during maintenance.
How does a wall cap prevent mouse from entering?
The interior of the wall cap usually equipped with insect-proof nets or automatic louvers that return by gravity/spring. When the HRV stops operating, the shutter automatically closes, blocking the passage between the pipe and the outside. If the pest-proof net is damaged or the shutter gets stuck, small animals may crawl into the room along the ventilation duct. Therefore, the integrity of the wall cap should be checked once a year.
What is the required installation spacing for the exterior wall caps?
The air intake should be at least 1.8 meters horizontally away from the wall caps. Vertically, the exhaust vents should be above and the air intakes below, with a spacing greater than 1 meter. If the distance is too close or the orientation is incorrect, the wet and cold exhaust air will be re-inhaled by the air intake, resulting in a decrease in the efficiency of the heat exchange core and even causing unpleasant odors in the indoor area.
