When we have two chillers, we need to consider how they are staged. We have the sequencing type [listed here]. Typically we have Parallel or Series, but we have a number of other options here. If you hit the F1 key, you get the Help file. You can do this in any screen. We can look at the sequencing types, and we can read through these. Typically, parallel is something that, I think, often operates more efficiently, though it would depend on who you talk to of course, and that’s definitely not always true. In this case, just going with my gut, I would imagine that Parallel is more efficient just based on this chiller type, so I’m going to select Parallel. I want to save that, and I want to select Parallel for this chiller as well, That way once we get to 600 tons, each chiller will be running at 300 tons, as opposed to one chiller running at 600 tons and the other chiller being on and off for whatever’s needed for that portion of the hour where we’re over 600 tons.

So if you follow, say we were at 650 tons. In Parallel, that will split the load. They will both run at 325. If they were at Series, the first chiller would run at 600 tons, full-blast, and the other chiller would run, in theory, at 50 tons, which of course is something that the chiller probably wouldn’t operate at, so it would probably operate at 100 tons for part of the hour and then turn off, and then operate again, because large chillers cannot operate at such low tonnage. That’s another thing that happens with Series sequencing.

Of course, most of you already know that. The main difference here would be the economic definition. There’s a reason that we’re evaluating this, and one of these costs more than the other to implement. Most likely, the two small chillers cost more to install. Now we just go ahead and click “calculate” and “view results.” It will calculate that. This simulates pretty quickly, because it did the earlier simulation to develop that load profile.