I agree. I once had a to buy a professor's book. It was $240.00 of confusing sentence structure, no diagrams(other than manafacture's publicity material, written terribly). He actually made a slightly complex topic seem like we were finding the "God Particle".

As to his profit, I'm not sure how much he made off of each book, but the book is used across the world. The only reason I think any instructor would use his book is because it's a niche subject matter; the mechanics and theory of hydronic heating systems.

If Dr. Hydronics ever reads this--you're probally a nice guy, but you made a relatively simple subject complex. Funnel your sentences. Use numbers. Don't use unnessary words. KIS(keep it simple).