How to use water heater diagrams:
Air Speed. Starting from 250 m3/h on the air flow scale draw a vertical line 1 till the air speed axis which makes about 3.75 m/s.
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Supply air temperature. Prolong the line 1 up to the point where it crosses the outside air temperature (blue curve), e.g. -15°C; then draw a horizontal line 2 from this point to the left till crossing water in/out temperature curve (80/60 °C). From this point draw a vertical line 3 to the supply air temperature axis on top of the graphic (+27°С).
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Heating coil capacity. Prolong the line 1 up to the point where it crosses the outside air temperature indicated as red curve (e.g., -15°С) and draw a horizontal line 4 from this point to the right to the intersection of water in/out temperature curve (e.g., 80/60 °С). From this point draw a vertical line 5 up to the scale of heating coil capacity (5.2 kW).
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Water flow. Prolong the line 6 down to water flow axis at the bottom of the graphic (0.067 l/s).
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Water pressure drop. Draw the line 7 from the point where line 6 crosses the black curve to the pressure drop axis. (5.2 kPa).
