What's the correct setting for a high-temp limit switch? 200 or 210?

I know that one of these questions specifically identifies an electric furnace but it’s still a bit confusing to study 2100 questions and have these two questions be almost identical but with slightly different answers. So, I’m wondering why they are so slightly different. I doubt I would make the mistake of choosing 195 but that would be closer to 200 than 210. And 212 is closer to 210 than 200. Very subtle differences. Is there some sort of rule to go by or should I just memorize these numbers as slightly different for electical furnaces than everything else?


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This is a “Not to Exceed” question.

This whole training is to make you think and not just memorize numbers.

The Equipment Mfg. sets the specification for the device. It should be replaced with the same rated device. I do not know when any HI is going to be checking the High Limit Safety Device. It is good to know this stuff if you find a problem with the furnace short cycling and notice a 185F limit switch. But that is someone else’s job is it not?

Way back in the day, there were fan controller/hi limit switches. The fan control was mostly the only adjustment on the device. I think by now almost all have found their way to the recycle center…

The thing your most likely to find concerning these limit safety devices is dirty coils and filters, restricting air flow and overheating the heat exchanger and short cycling the gas valve.

For the two questions you posted, look at the temperature difference of your choices. Just know which is low and which is getting too far up there. Pick the one in the middle.

This training is getting you ready for the big test, and you’re going to pull your hair out over that one!


That’s probably good advice for the test, but I kind of feel like a noob if a client asks me what the typical setting is and all I can say is the the study material was unclear on this topic. I guess I’ll probably feel that way until I’m not a noob anymore.

ScreenHunter_287 Sep. 08 10.48
This is what a limit switch looks like. Only the bottom right has an adjustment (and you have no way to determine the adjustment).

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