dumb hot air furnace question

Is the fan before or after the heat exchanger? I.e. is the heat
exchanger under positive or negative pressure?
Pondering

The air path in the hot air furnances that I've had is: cold/return
air-->filter-->blower-->heat exchanger-->plenum-->humidifier-->supply pipes.

So, if anything, there is a slight positive pressure in the area around the
heat exchanger relative to room air.

I don't think that is a dumb question, and the answers were
interesting.

And remember, there is no such thing as a dumb question. Only a dumb
person.

What if they start asking questions though?

Darn.

LOL

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me know if you have posted also.

Then you have "dumb person questions," which is
really what is commonly meant by a "dumb question."

Case rested :)

FTR, I left off the smiley but I was kidding.

I had a girlfriend for a while, and one of her big complaints was that
I asked questions, the answers to which were obvious.

I hadn't noticed this, but I spent years paying attention, and it was
true.

But it was still a good idea. I usually got more information in
return than I already knew.
Sometimes what I thought was the answer wasn't.
And people don't like it when you start off with a really hard
question. But if I ask an easy question first, and he answers it and
I appreciate the answer and show it, we're both happy. If I have
another question, he'll make a bigger effort to answer it.

This happens with me especially if I'm just watching someone working
in public, who has no responsibility to answer my questions at all.

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Mine's a big-ass squirrel-cage that forces air TO the
heat-exchanger, presumably also because on the other
side all the parts would have to stand up to more heat.

positive pressure usually