Lync AEGIS
2: INTRODUCTION
L-OMM-012_A
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4/20/2022
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2.7. High Inlet Temperature (Hit) Function
The HIT function allows the heat pump to operate even with inlet water temperatures above the
standard limits. It is utilized:
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for the anti-Legionella treatment (tank temperature > 60 °C (>140°F), see below)
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when domestic water recirculation is used with low water demand
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when heat pump stops for a long time and the tank thermally stratifies.
2.8. High Pressure Set Point Calculation
The high pressure set point is not fixed, but instead is calculated based on inlet water
temperature, outlet water temperature, and evaporation temperature. The pressure is managed
by the thermostatic valve.
The setpoint value is limited between a minimum and a maximum fixed value. Within these limit
values is also active a compensation curve based on the evaporator temperature that keeps the
compressor within the required operating envelope.
2.9. Anti-Legionella
Legionellosis is an infection caused by aerobic bacteria of the genus Legionella that mainly affects
the respiratory system. The name of the disease derives from the fact that the bacterium was first
identified in 1976 on a group of participants in a gathering of the American Legion in a
Philadelphia hotel, on that occasion 291 people contracted the disease and 34 of them died.
The proliferation of Legionella depends on the water temperature. As can be seen from the chart
below, the disinfection is feasible through thermal shock.
Figure 1: Legionella Growth Chart
1
The anti-Legionella function consists in bringing the water storage tanks to a high temperature
and subsequently carrying out a recirculation to ensure complete disinfection of the system.
1
Freije, Matthew R.
How to Make Plumbing Systems Less Conducive to Legionella and Other Bacteria
. HC
Information Resources, 1998. .