Should I tip the guy installing carpet at my house. If so, how much? He doesn't own the business, he's the installer for the company from which I purchased the carpet.

I would say no, he is either a contract or employee of the carpet company most likely making more money a hour than you are.

Should I tip the guy installing carpet at my house. If so, how much? He doesn't own the business, he's the installer for the company from which I purchased the carpet.
I usually try to tip someone who is doing physical work for me (installers, fixers, etc.). But I think I do it more for myself since I have seen them at work and I tip if I felt they did their job well.

If he's not the owner and he does a good job then I'd give him a little something, say $20.

Any time physical labor in particular is involved I would always try to tip someone. I don't know about installing carpet, but I worked off and on as a professional mover for almost a decade, and we made a heck of a lot less than most people would assume, the same with landscaping. Twenty dollars is a very respectable tip, and such was always truly appreciated. It never hurts to be a bit kinder than is perhaps necessary. :)

If you think he did a prompt good job I would tip.

NO, trust me you tip them in the price you pay to have it installed... you could offer the person something to drink during the time (soft drinks only)