Having recently installed this to replace an old Vent-Axia fan that made a racket, after several weeks of use, seriously impressed at this fan. The ability to determine the humidity level at which to operate the boost mechanism is a serious plus point and this has proven to be extremely adaptable, Then there is the pull cord if you wish simply to give it a boost regardless of any humidity setting. Even in the boost mode it is still an effortlessly quiet device. It is clear from holding my hand in front of the inward air flow that that the heat exchanger is way more effective than in the old Vent-Axia. Fingers crossed regarding reliability and longevity.