10
Performance chart for the VUT 1500 WH-4 water heater parameters is shown in Fig. 7.
Fig. 7 Calculation of the VUT 1500 WH-4 water heater parameters
Water heater parameters calculation example:
Air Speed. Starting from 2000 m3/h on the air ow scale draw a vertical line till the air speed axis which makes 3.75 m/s.
Supply air temperature. Prolong the line up to the point where it crosses the outside air temperature (descending curve, e.g. -15°C) then draw a horizontal line from this point to
the left till crossing water in/out temperature curve (e.g. 70/50). From this point draw a vertical line to the supply air temperature axis on top of the graphic (31 °C).
Heating coil capacity. Prolong the line up to the point where it crosses the outside air temperature (ascending curve, e.g. -15°C) and draw a horizontal line from this point to the right
until it crosses water in/out temperature curve (e.g. 70/50), from here draw a vertical line up to the scale representing the heating coil capacity (35 kW).
Water ow. Prolong the line down to water ow axis at the bottom of the graphic (0.43 l/s).
Water pressure drop. Draw the line from the point where line crosses the black curve to the pressure drop axis. (9 kPa).
Air temperature at outlet from the heater [°C]
Air speed inside the heater [m/s]
Water ow through the water heating coils [l/s]
Water pressure drop [kPa]
Air ow through the heater [m3/h]
Coil heating capacity [kW]
External air temperature [°C]
Performance chart for the VUT 2000 WH-2 water heater parameters is shown in Fig. 8.
Fig. 8 Calculation of the VUT 2000 WH-2 water heater parameters
Water heater parameters calculation example:
Air Speed. Starting from 2000 m3/h on the air ow scale draw a vertical line till the air speed axis which makes 3.75 m/s.
Supply air temperature. Prolong the line up to the point where it crosses the outside air temperature (descending curve, e.g. -15°C) then draw a horizontal line from this point to
the left till crossing water in/out temperature curve (e.g. 90/70). From this point draw a vertical line to the supply air temperature axis on top of the graphic (22 °C).
Heating coil capacity. Prolong the line up to the point where it crosses the outside air temperature (ascending curve, e.g. -15°C) and draw a horizontal line from this point to the right
until it crosses water in/out temperature curve (e.g. 90/70), from here draw a vertical line up to the scale representing the heating coil capacity (28 kW).
Water ow. Prolong the line down to water ow axis at the bottom of the graphic (0.35 l/s).
Water pressure drop. Draw the line from the point where line crosses the black curve to the pressure drop axis. (3.8 kPa).
Air temperature at outlet from the heater [°C]
Air speed inside the heater [m/s]
Water ow through the water heating coils [l/s]
Wa
a]
Air ow through the heater [m3/h]
Coil heating capacity [kW]
External air temperature [°C]
