Another Plumbing Question

I'll follow cyberwollf's lead and throw in another non-homebrew plumbing question.

My neighbor came over to ask me to take a look at his new furnace installation. He's not too happy with it, but I don't have any answers so hoped someone here could help. Lots of questionable workmanship, but the biggest concern is the reduction in pipe size. The house is a pretty big ranch with one zone. The main pipe exiting the old furnace and running through the house was about 1-1/2" diameter. The pipe coming out of the new furnace is the same size, but for some reason he reduced it to what looks like 1" for the short runs he made between the furnace and the existing plumbing on both the in and out lines.

Is there a reason for this or did the guy just cut corners and use the pipe that he had available. The installer was a private subcontractor hired by Sears to do the installation.

You can see the four points where the pipe goes from big to small in this picture.

Only one bump (I promise.)

Reducing pipe size, good or bad?

Hoping there might be someone on now who wasn't here over the weekend.

I can't claim to have much plumbing knowlwdge, so take this with a grain of salt.
Your circulators are likely not moving the water at tremendous pressure. A bit of a bottleneck at any point should have minimal impact. If this were the clean water source for usage of appliances, I would be more concerned.

If it was done by a sears subcontractor contact sears.
They put a homeowners satisfaction promise.

Thanks for the input.

And to TxBrew for the link he PMed.