Ventilation Details Sought To the Editor: In Mr. Rosenbaum's excellent article, "Simple Ventilation for Tight Houses" (5/91), he did not touch upon two items of some importance: • details for connections to drain condensation in ductwork where the air is flowing down towards the fan; • accessibility for cleaning duct and practicality of cleaning flexible duct. I would be interested in Mr. Rosenbaum's experience with these matters. Kenneth Kruger, P.E. Cambridge, Mass. Marc Rosenbaum Responds: In my house, I have a length of clear, uninsulated flexduct on the exhaust side just ahead of the heatrecovery ventilator (HRV) because I was concerned about both issues raised by Mr. Kruger. I can check it easily for dust or condensation. There is a bit of wood dust inside the duct which appeared