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When two branches come together, we propagate the individual parts of the flow :
domestic hot water (DHW)
heating prioritised by DHW (e.g. when HIU’s are applied)
heating not prioritised by DHW (e.g. when electric heaters are applied)
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In the example below we propagate two DHW flows
DHW flow 1, with total power P1, diversity flow v1, and diversity factor f1
DHW flow 2, with total power P2, diversity flow v2, and diversity factor f2
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The question is : how to calculate the diversity factor f3, total power P3 and diversity flow v3 for DHW?
We calculate these in following order :
P3 = P1 + P2 (first law of thermodynamics)
f3 is recalculated based on the applicable diversity standard, applied on the TOTAL amount of tapflow or TOTAL amount of dwellings on the secondary side.
The diversified power is equal to f3 * P3
the supply temperature t3supply is defined by the user
the return temperature t3return is calculated as the mixed return temperature of flow 1 and flow 2 (v3 * t3return = v1 * t1return + v2 * t2return). This means that the return temperature is not a direct result of the diversity, but a result of the components (like heat exchangers) and the mixing rules
the diviersity volume flow v3 is calculated using the formula
in which P is the diversity power f3 * P3, m is the diversity massflow (which can be converted to the diversity volumeflow), T1 is the return temperature t3return, T2 is the supply temperature t3supply
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Allthough P1 + P2 = P3 it is important to mention that :
This is a typical effect of the diversity, and sometimes experienced as contra intuitive |