Water Heater Replacement rules

[Gagan P.]

Anybody know the rules for replacing water heaters these days?
Had a company that AHS sent over last year that replaced a heater, no issues.

Different tech this year, same subdivision, different property, same setup (no pressure reducing valves and no pressure tank), and tech claims it needs "Sediment trap, expansion tank, T&P modifications, and permit", essentially more than what AHS says the new tank itself is worth.

Figured I'd ask here if anybody knows the exact regulations, because the tech seems not to want to explain anything other than "We can't tell you by law, only American Homeshield can, we've told them what it needs". AHS says "They told us what it needs, we don't know what the rules are, we rely on the contractor for that".

When I mentioned the other property (before realizing it was the same company) had an issue last year and no fuss about an expansion tank or T&P or anything extra, he said "They probably did it illegally then". I didn't realize until after that the SAME company went out for the other property.