A variable heat source portable heat exchanger includes a collapsible main heat exchanger chamber fabricated from heat reflective material on 5 sides with the sixth side being a fire proof heat conductive material facing a heat source. The system uses a heat reflective enclosed conduit that has separated continuous inner chambers along its length stretching between the collapsible main heat exchanger chamber and the shelter environment. One chamber draws clean air from the shelter environment to be warmed into the main heat exchanger chamber where it passes across a fire proof heat conductive material. Air lingers in the heat exchanger chamber long enough to be warmed by the radiant heat source through the heat conductive surface. The other chamber cycles the warmed air back to the desired environment with the possible aid of but not limited to an airflow-enhancing device. A convection air current created by the temperature difference between the heat exchanger chamber and the shelter environment draws air through the system.
