Whole house balanced ventilation is relatively new in the UK and many of the problems reported by users relate back to poor installation and commissioning.

To help me design better systems and to find out first hand about reality on site I decided to dust off my tool bag and got the opportunity to install this system at Cocreate’s Whipley Lodge Passivhaus project. I’ve put down some of my experiences to help me remember, and to help other designers and anyone considering installing.

Design lessons

• Make sure the rigid connection between the unit and the external wall allow for installation. At least one bend is required here. Very short ducts have to be installed before the unit and this needs to be clear in design information.
• Preference for fan units that have internal frost protection, the external box and associated cabling seemed an add on which wasn’t well thought through.
• Make sure the control panel for the system is on the drawings and there’s a spec for the cable.

Installation lessons

• Insulate the exhaust and inlet ducts through the wall with a short length of insulation at first fix. Carry out all sealing and air-tightness measures back to the external wall at this time.
• Provide very robust temporary sealing to the duct ends post first fix.