First you need to take some short term courses in HVAC design in any quality school to learn the basics for HVAC design, at the same time improve your knowledge in HVAC by reading the contents in mepanet.com and ask any related question to get an answer from the experts. When you feel that you are ready to work in design phase then apply for an entry level designer/ drafter in any MEP firm which will accept you. Once you get into the firm, you should be real active for learning from the senior engineers to grow.
