TL;DR, teach people how to read their own schematics (is it safe to do so? IDK: for some it will provide a false sense of competence; others it may save their life).
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That answer is comprehensive but on it's way too becoming to broad, especially if you take my suggestion of somehow adding more information about how to read a schematic and how to apply it to the real world.
If people knew what they were doing they wouldn't have to ask, and they certainly don't know what to say over the phone to the manufacturer:
"...and may not be approved by every manufacturer. Check with the furnace manufacturer..."
People ask a new question because they want you to answer this; here's my model numbers, now do the math please... (and draw me one of those nifty-colored-idiot-prof diagrams for my furnace).
If I had a schematic of anything I didn't understand, I'd bring it before you, regardless of on-topic or not. Because you're really, really good at understanding them and making people understand them (+1 for non-hand drawn red circles).
No. They keep making new and different ones; you're gonna have to keep drawing red and blue lines on people's specific schematics.
Apples and oranges:
What size wire for my garage?; now, that's been put to bed I hope. At least that doesn't keep changing, like thermostats and furnaces. I have one good question here, How To Do Tile. I asked it partly because it seemed that no one else had, and as a go-to for: all of your concerns are answered here. For tile you can pretty much get away with that; electrical schematics, not so much.
Admittedly though, I did not ask my question to close dups... It's more for leaving a comment: see here, or for a short answer with: further reading.
A 'hold' on questions that can be lifted by the OP, by simply editing the post or something like that.
Your question has been placed on hold because it is believed to be a duplicate of this question. If the answers to that question do not provide a solution for you, click the button at the bottom of that page to re-open this one.
This may just be a roundabout way to deal with my pet peeve of post abandonment, but it'd be a good way to make people read that other question, and it be OK when they don't come back to their own; it'd have been dealt with: on hold and on its way to being closed. Also, it should only require
X rep; not 5 people seemingly ganging up on some poor new user, for which they can basically do nothing if y'all think it's a dup.
Stack Exchange exists as a repository of Q&A's; it's main goal. However, to usefully achieve that goal it must help people to understand their specific situation ("please explain to me..." -the FAQ).
Until we have addressed Every Single Possible Conundrum Ever, our work is not done.
I ask you:
(out of sheer boredom at this point)
When you close a
C wire question as a dup, did you pull up the schematics of their equipment and verify that it is indeed answered elsewhere, or do they still need to verify that with the manufacturer? If so, your entire answer is useless to the common noob; information-overflow.
Don't get me wrong, it's an excellent answer to Google across, but not if you need the concepts behind the concepts explained to you: i.e., reading schematics... (and as expressed in meta questions concerning safety, you should not be explaining electrical concepts to novices anyway).
I realize that is what your answer has tried to accomplish; teach furnace schematics. But what it really needs is real world pictures showing where the things on that diagram are. Which will however be different for each person's unit. So again: no.