Two separate concentric tubes are arranged in parallel in a U format to reduce the overall length and to provide a mid-position measuring point. The heat exchanger is mounted on the H102 panel fascia and retained by locking pipe clips.
In normal operation, hot water from the heater and pump passes through the ‘HOT OUT’ braided hose and self-sealing coupling into the inner stainless steel tube. It then flows through the heat exchanger and leaves. Cold water flows from the ‘COLD OUT’ hose through the annulus between the clear plastic tube and the inner stainless steel tube. With the hot water in the inner tube, losses from the system to the outside are minimised while still allowing students to see the construction of the unit. As the cold stream warms above the ambient temperature however there will be some external losses.
Compression fittings provide a liquid seal between the stainless steel tubes and the outer annulus. This also allows the stainless steel tubes to be removed for cleaning if necessary. Six thermocouples measure hot and cold inlet, mid-point and exit temperatures.
