INSTALLING MECHANICAL VENTILATION WITH HEAT RECOVERY

The installation of an MVHR system involves adding a series of ducts, fans and other integral components to your home. Here’s how it’s done and who you'll need to install it

- DAVID HILTON

MVHR systems are designed to both improve the air quality within your home, and provide fresh warm, heated air. However, unlike more simple ventilation products, such as extractor fans or air bricks, MVHR systems are made up of a number of different components. The fan unit is the main heart of the system as it has the heat exchanger and two fans, one to draw air from the home and one to supply air to the home. Add to this room terminals, ducting systems and condensate outlets, and MVHR installation is more complex than it might first appear.

DESIGNING YOUR MVHR INSTALLATION

In most projects, especially a new-build home, if you’re including an MVHR system, you should receive drawings of the proposed ductwork design from your MVHR suppliers.

If you're undertaking a self-build project, the drawing will need to be modelled into the architectural and Building Regulations drawings at an early stage in order to take into account any structural details, such as joists, steels and fire compartment walls. In order to comply with Building Regs, it’s essential to get the design right, as flow rates will also need to be calculated and the correct duct sizes specified to make sure that the system meets the requirements. In an existing home it can be very difficult to get detailed drawings of where all the joists and services are, so these finer details may need to be finalised during the installation.

WHAT'S NEEDED FOR YOUR SYSTEM?

MVHR requires a network of ducts being built into the structure of your home. These ducts can either be a rigid branch design, or semi-rigid ducts, both of which will need to go back to the fan unit. The rigid branch design systems can be better suited to new-build installations as the ducts are larger and do not flex.