VUT R 900 WH EC

Calculation of air temperature at heat exchanger outlet:

t = t_int+k_eff*(t_ext - t_int) / 100,

Where  

t_int - intake air temperature ⁰С,      

t_ext - extract air temperature ⁰С,    

k_eff - heat exchanger efficiency (as per diagram), %

Calculation of water heater parameters 

How to use water heater diagrams: 

Air Speed. Starting from 650 m³/h on the air flow scale draw a vertical line ¹ till the air speed axis which makes about  2.35 m/s.

• Supply air temperature. Prolong the line ¹ up to the point where it crosses the outside air temperature (blue curve), e.g. +5°C; then draw a horizontal line ² from this point to the left till  crossing  water in/out temperature curve (70/50 °C). From this point draw a vertical line ³ to the supply air temperature axis on top of the graphic (+26°С).
• Heating coil capacity. Prolong the line ¹ up to the point where it crosses the outside air temperature indicated as red curve (e.g., +5°С) and draw a horizontal line ⁴ from this point to the right to the intersection of water in/out temperature curve (e.g., 70/50 °С). From this point draw a vertical line ⁵ up to the scale of heating coil capacity (5.8 kW).
• Water flow. Prolong the line ⁶ down to water flow axis at the bottom of the graphic  (0.04 l/s).
• Water pressure drop. Draw the line ⁷ from the point where line ⁶ crosses the black curve to the pressure drop axis (0.5 kPa).