5. Find the mix point M by measuring the length of the line O-R and multiply this by the mixing ratio.
On a full size CIBSE psychrometric chart this measures 85mm.
The ratio of recirculated air is 0.8. …….. therefore; 85mm x 0.8 = 68mm
Measure down the O-R line from point O by 68mm.
This determines point M .
6. Find the room ratio. This is the sensible to total heat gain ratio.
Total heat = 8 kW sensible + 2 kW latent = 10 kW total.
Heat ratio = 8 / 10 = 0.8
Plot this ratio on the protractor, bottom segment, on the psychrometric chart and transfer this line onto the chart so that it passes through point R.
7. Plot the Apparatus Dew Point ADP of the cooling coil.
This is on the 100% saturation curve. The ADP is 80C.