Abstract: A heat exchanger includes a corrugated metal sheet comprising a first side having a plurality of first troughs alternating with a plurality of first peaks, and a second side having a plurality of second troughs alternating with a plurality of second peaks, each trough being formed by a pair of walls, each wall separating the first side from the second side and extending from a first peak to a second peak, the troughs and peaks extending in parallel and defining a longitudinal direction. Each first peak is formed with at least one depression, the depressions in respective peaks being aligned to form at least one tube-receiving channel extending transversely to the longitudinal direction. Each depression has a contact surface formed in the first side and extending laterally over each adjacent first trough. A tube section is received in each tube-receiving channel in substantially conforming contact with the contact surfaces.