04 Oct Ventilation air ducts for MVHR: materials and quality
Ventilation and air duct tubes allow mechanical ventilation heat recovery (MVHR) systems to continuously renew the air inside buildings. In dual-flow MVHR systems, the air is renewed in four phases:
- Intake of fresh air from outside the building
- Filtering and heat exchange with the air extracted from the building
- Introduction of treated air in the main environments of the home (living room, bedrooms, corridors)
- Extraction of stale air from minor environments (kitchen, bathrooms, walk-in wardrobes)
This uninterrupted exchange allows for raising the quality of the air we breathe, while keeping the environment thermally and acoustically insulated from the outside.
The quality of ventilation air ducts
It is essential not to underestimate the quality of ventilation air ducts to be fitted in a MVHR system, because they determine the final performance of the entire system. The tubes currently available on the market are produced with the following raw materials:
- HDPE (high-density polyethylene)
- MDPE (medium-density polyethylene)
This polymer is derived from petroleum that is commonly recycled. Owing to its physical resistance to solvents, PE is very widely used, for example for:
- Detergent bottles
- Jerry cans for vehicle fuel
- Lubricant containers
- Plastic furniture
- Door and window frames
All these uses necessarily leave residues of the base raw material.
Ventilation air ducts made of recycled materials
Polyethylene ventilation air ducts should not contain recycled raw materials. An MVHR extruded duct with post-consumption recycled polyethylene has serious defects that hinder its efficacy during use:
- Potential release of chemical residues of unknown origin in the air
- Possible odour pollution of the air
- Irregularity of the inner tube surface due to material residues, which favours dust build-up
- Irregularity of the thickness of the inner layer, with potential cracking of the latter
These aspects will adversely affect the QUALITY of the air inhaled inside the home. The air drawn from the outside and filtered by the machine risks being polluted if the system is not equipped with CERTIFIED MVHR AIR DUCTS.
MVHR air ducts made of virgin raw materials: white ducts
How can we recognise extruded air ducts made of virgin raw materials? The first obvious answer is to rely on an experienced sector professional with references.
The second is to demand:
- Certified air ducts
- Controllable references
- Tubes that are preferably WHITE, BOTH INSIDE AND OUTSIDE
Slightly translucent white is the natural colour of HDPE granules. Therefore, a corrugated air duct that is white both internally and externally must have been extruded with virgin raw materials.