'as _____ as' is used with other adjectives. "as fast as", "as big as", ect. With "same", you use 'the same as'. If the two things are exactly the same, you just say "My book is the same as his book." Or "My dog is the same as her dog." If there is just one part that is the same, you say "the same _____ as". "We'll maintain the same temperature as the tank." is more natural. You can also use this for other sentences. "My bag is the same color as her bag." "My house is the same size as his house." "I will do the same work as he does."