La thermal power to devote to the production of sanitary hot water, depends on the type of production, if snapshot or with backlog.
In systems with heat pump is to choose the production with accumulation in order to avoid Frequently ignitions e shutdowns in correspondence of the peaks of demand, counterproductive for the compressors of the unit.
The most widespread system provides for a tank accumulation, the capacity of which must be sized appropriately, equipped with a serpentine heat exchanger in which circulates the water that is heated by the heat pump.
La power required to achieve and maintain the desired water temperature, can be dispensed is at the request of the tip, both in the absence of request being stored in the accumulation heat.
La power the generator and the volume accumulation are inversely proportional because the greater the requirement instantly satisfied the smaller the required volume
Vc = ((Qm * Dp * (Tm - Tf) / (Dp + Pr)) * ((Pr/ (Tc-tr)) = Liters accumulation
P = ((Qm * Dp * (Tm - Tf) / (Dp + Pr)) * = 1 Watt generator
dp: Tip life (h);
Qm: Maximum hourly demand hot water (l);
tm: Operating temperature hot water (° C);
tf: Temperature of the cold water from the aqueduct (° C);
tc: Temperature of hot water storage (° C);
Pr: Duration of the preheating (h).
As a criterion to be followed in the choice of sizing parameters you should not exceed in either the volume of the storage nor in the power of the heat pump.
For the temperature of aqueduct reference can be made atf = 10 ÷ 15 ° C, while the temperature of use assumes tm= 40 ° C.
For the production temperature of the hot water must consult the operating limits of individual heat pumps, it being understood that this temperature may vary in the range of 50 ÷ 55 ° C; accordingly to the temperature of accumulation reference is made atc= 48 ÷ 50 ° C.
Also the duration of the period of preheating has its importance for the proper sizing; usually assume dp= 1 ÷ 3 h.
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