I once had a similar problem, it turned out to be a short in the thermostat wiring.

I’d sue for false advertising. Marketing people…..sheesh…and they give degrees for this stuff….lol.

I can’t imagine the circuit for this is all that complicated. I’m guessing that you have a bad ground somewhere.

When the furnace kicks on the motor draws so much current so fast that the ’short’ loads up and causes the fuse to let go.

Finding it is another matter, but liike I said, I can’t imagie it being al that tough to trace out.

If you are handy with these kinds of things, just go look at it. You may notice a wire that is loose, or off, or poorly connected.

Often things like this are obvious, simple things.

However if you do go poking around, make sure you unplug things or turn off the breaker to the furnace so it won’t try and kick on.

I think most of these systems have the curcuit on the access panel. As long as it was done with standard schematics you have a chance of finding what’s wrong.

If, on the other hand, they are using ‘industry’ schematics then you probably won’t know one thing from another. But it’s still worth giving things a ‘visual’ and see if you see anything.

Good luck to you.