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The direct units don’t have a coil as a heat exchanger hydraulically separating the primary side with the secondary side, while the indirect units do. The hydraulic separation is in most cases needed when glycol is used on one side and not on the other.
The electrical storage units have an electric resistance embedded into the thermal store therefore also functioning as a “production” unit besides being a thermal store.
Besides the visualised visualized base circuits (BCs) above, more BCs are available combining different types or allowing multiple connection possibilities.
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If the user doesn’t change any of the parameters and lock locks it, both the design heat flow and temperature regime is are propagated from the end-unit side (secondary side) through the thermal store to the production side (primary side).
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Remark: When the thermal store has only 1 connection at the top and/or 1 at the bottom, the user can enter 100% for the supply connection (on both sides) and 0% for the return connection (also on both sides). This way the visualisation visualization shows 4 connections going to the thermal store, but in simulation, it is actually accounted for only 2 connections. The single pipes towards the top and/or bottom of the thermal store are however not dimensioned and included in the simulation.
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