Sensible Heat Ratio on psych chart

[Seaside]

What is the Sensible Heat Ratio on a psychrometric chart a ratio of and what
is it's purpose?

Thanks
Steve

[Abby Normal]

The sensible heat ratio is a slope for a line on the chart.

The ratio is the sensible heat divided by the total heat.

Example total load is 24,000 Btu/hr of which 18,000 is sensible heat and
6,000 is latent heat. The ratio is 0.75.
Three quarters of the load is sensible. You draw a line on the chart
starting at the entering air conditions with a slope parallel to the
sensible heat ratio.

The required supply air conditions to handle the 24,000 load will fall on
this line. Determine what supply dry bulb temperature you are aiming for and
see where it intersects the line. You can then tell what the supply wet bulb
temperature will be and what the design CFM should also be.

On Carrier and Trane Charts there is usually a reference point on the chart.
You put the left end of a straight edge on the reference point and the right
end of the straight edge on the SHR scale on the right of the chart, draw a
line and get the slope. Then you draw a line parallel to this line that
passes through your entering air condition.

With ASHRAE charts, there is a protractor in the top left corner that you
use to get your slope.

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