A quick question - how much heat is lost through a fan running continually at n litres per second (currently 6) with temperature differential delta-t (currently prob. 15-17C)?   I have replaced my fans in both bathrooms with a pair of Vent-Axia Lo Carbon Centra-T devices, which run at either 6 l/s or 9 l/s continuous setting. Before one was a bog standard thing installed by the (self) builder, and the other one downstairs was an Icon Airflow I have had in for a few years. Unfortunately