System for providing a controlled temperature in a control volume, comprising: a main chamber defining the control volume, and having at least one main chamber inlet and one main chamber outlet; a mixing chamber having a mixing chamber outlet in selective fluid communication with said main chamber inlet, at least one mixing chamber inlet, and a ram air inlet different from said at least one mixing chamber inlet for allowing a ram airflow at a first temperature to be channeled into said mixing chamber; a gasflow source in selective fluid communication with said at least one mixing chamber inlet and configured for selectively providing a source gasflow at a second temperature to said mixing chamber, said second temperature being greater than said first temperature; wherein said mixing chamber is configured for: - in the presence of said source gasflow in said mixing chamber, selectively allowing said ram airflow and said source gasflow in said mixing chamber to mix therein to provide a mixing chamber outflow to the main chamber; or - in the absence of said source gasflow, selectively allowing said ram airflow in said mixing chamber to flow to the main chamber to thereby provide a mixing chamber outflow; said mixing chamber outflow being at a third temperature at least at or near said main chamber inlet; a control system operative to control at least one of said ram airflow, said source gasflow and said mixing chamber outflow to provide a desired said third temperature at least at said main chamber inlet; wherein said main chamber comprises an auxiliary outlet, and said gasflow source comprises a recirculation conduit connecting said auxiliary outlet to said mixing chamber inlet and configured for providing a recirculating airflow from said main chamber into the mixing chamber to thereby provide said source gasflow. a main chamber defining the control volume, and having at least one main chamber inlet and one main chamber outlet; a mixing chamber having a mixing chamber outlet in selective fluid communication with said main chamber inlet, at least one mixing chamber inlet, and a ram air inlet different from said at least one mixing chamber inlet for allowing a ram airflow at a first temperature to be channeled into said mixing chamber; a gasflow source in selective fluid communication with said at least one mixing chamber inlet and configured for selectively providing a source gasflow at a second temperature to said mixing chamber, said second temperature being greater than said first temperature; wherein said mixing chamber is configured for: - in the presence of said source gasflow in said mixing chamber, selectively allowing said ram airflow and said source gasflow in said mixing chamber to mix therein to provide a mixing chamber outflow to the main chamber; or - in the absence of said source gasflow, selectively allowing said ram airflow in said mixing chamber to flow to the main chamber to thereby provide a mixing chamber outflow; - in the presence of said source gasflow in said mixing chamber, selectively allowing said ram airflow and said source gasflow in said mixing chamber to mix therein to provide a mixing chamber outflow to the main chamber; or - in the absence of said source gasflow, selectively allowing said ram airflow in said mixing chamber to flow to the main chamber to thereby provide a mixing chamber outflow; a control system operative to control at least one of said ram airflow, said source gasflow and said mixing chamber outflow to provide a desired said third temperature at least at said main chamber inlet; wherein said main chamber comprises an auxiliary outlet, and said gasflow source comprises a recirculation conduit connecting said auxiliary outlet to said mixing chamber inlet and configured for providing a recirculating airflow from said main chamber into the mixing chamber to thereby provide said source gasflow.