3For the installer - 21 - ENSupply air Return airExhaust air Outside airComfoAir 200 - LeftReturn air Supply airOutside air Exhaust airComfoAir 200 - Right3.6.3 Connection of the air ductsInstall a silencer of at least 1 metre straight directlyonto the supply and return connections. For rele-vant advice, please contact Zehnder.Subsequently, the air ducts to be connected, with aminimum ø of 125 mm, must be installed with as lit-tle air resistance as possible and must be free fromair leakage.• Do not use fl exible ducting and leave room formounting silencers.We recommend that the ventilation system befi tted with intake and exhaust valves made byZehnder.• Insulate the outside air supply and the air ex-haust duct between the roof/wall passage torender the ComfoAir damp proof. This preventsthe formation of condensation on the outside ofthe ducts.3.6.4 Connection of the condensation drainWarm exhaust air is cooled by the outside air in theheat exchanger. This causes the moisture in theindoor air to condense in the heat exchanger. Thecondensation water created in the heat exchangeris fed to a PVC condensation drain.