Psychrometric Chart Download Link Here

Sensible Heat Ratio is pretty much what the name implies; its the ratio of the sensible load in the space to the total load.

Psychrometric Chart Download Link Here

You can get a copy at this link and a overview document that also includes the download link here.

Thats about a 30 discount relative to what the Hands Down chart would cost if you just went and bought it on your own.

So a big thank you to Ryan for making this available to the industry and to Hands Down Software for offering the discount.

The links below will jump you to topics of interest, since this is another long post.

The Return to Contents like at the end of each section will bring you back here.

We are using 75F as our dry bulb temperature and 50 RH as our indication of moisture.

So at a minimum, to get a point on the chart, you will need to type in.

You will also need to pick the units of measure for this point (RH, Wet Bulb, etc.) using the drop down menu to the left of the box where you enter moisture content number.

For instance, here is what things look like if I select B for Below instead of AR for Above, Right in the Label column.

This will add another row to the table and, when we click Apply, will plot the point on the chart.

By selecting Copy Chart Image to Clipboard from the Edit dropdown menu, I captured the image to my clipboard.

I can then paste it into other applications like Word or PowerPoint or Excel for making a report or for illustrative purposes in this blog post.

But we discuss it in the VAV Systems, Design, Performance and Commissioning Issues class at the Energy Center and this link will take you to those slides, which should give you a sense of how it is done and why different load conditions require different coil leaving a conditions.

You may have noticed that there is a column labeled Process in the Psychrometric Processes window.

If you click into that cell, you will discover that there are a number of options aside from Add State Point.

Specifically, you can also pick Connect State Point and Cooling Coil.

When we do that, the Psychrometric Processes window changes a bit, as you can see below.

If we had more than one point on our chart, we could pick any of them using the drop down menu.

For our cooling process, the start point was the ASHRAE Space, so we will simply accept that and click Apply.

When we do that, the psych chart adds a line from the ASHRAE Space to the Cooling Coil Discharge that approximates the path the air would take as it passes through the cooling coil.

But as the air cools towards saturation, some of the heat transfer is in the form of latent energy (the energy that is keeping the water in the air in a vapor state; you and I detect it as a change in humidity).

If we change the process for the ASHRAE Space point from Add State Point to Connect State Point, we get this.

This line is a bit more theoretical than the cooling coil line and is a Sensible Heat Ratio (SHR) line.

Free Psychrometric Chart