Could someone explain exactly what is meant by the warning CAESAR throws, worded as follows: "A thermal load exists in the hanger actual cold installed load case"? The file I am checking has the following three (of a total of 20)load cases:
L1 W+H (HGR)
L2 W+T1+P1+H (HGR)
L3 W+T2+P1+H (HGR)

Is this just a warning so that the operator reviews it to make sure what he/she has done is right?

If you have (in the input) requested that the "actual cold load case" be computed, then that case is defined as "WNC+H", which I'm guessing should be your case #3. Note you have T3 in case #3, hence the warning.

How many operating conditions do you want considered in the hanger design (1 or 2), and do you want the actual cold load case evaluated?

We have a header with five branches, each terminating at a piece of equipment. Any one or several of the pieces of equipment could be in operation at one time - any not in operation would be cold. All could be in operation at once. The number of operating configurations would be large so we opted to define two temperature schemes (T1 & T2) which we consider bracket the full range of operation (all operating - T1 and only 1 operating - T2). Added to this is the fact that two (2) of the branches already exist and the client wants to be able to retain the spring hangers now installed on these branches.

We do not at present have a cold load case (WNC+H) defined. Note that the system carries a gas, so the contents weight is zero.

When I first checked this file I got the subject warning message. I assumed it was because the existing spring hangers had pre-defined spring rates and cold loads. So I deleted the cold loads, leaving the spring rates and I still got the warning.

Hope this is enough to allow for diagnosis. Thanks for your help Richard.

It will be faster to send the file in. Open a Support Request on eCustomer.

Here's my guess...
An earlier analysis specified more than one load case to set design parameters for spring selection. Then a second run was submitted with a different "multiple hanger load case setting". That upset the load case matchup. If I'm right, maybe all you have to do is click "Recommend" in the load case editor.
Just a guess.