Are you refering to the hot water storage vessel (copper cylinder). If you are then an indirect unit has one pipe entering at low level and one pipe leaving from top dead centre An indirect cylinder has the same two pipes but a further two entries half way up.
"Are you refering to the hot water storage vessel (copper cylinder). If you are then an indirect unit has one pipe entering at low level and one pipe leaving from top dead centre An indirect cylinder has the same two pipes but a further two entries half way up."
The cynic in me says that the OP is looking for help with his homework.
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