Select Your Manufacturer as Carefully as Your Equipment
A company that has been in existence for a number of years would be a good choice. You should look for a reliable and trustworthy team that operates within an endorsed quality system, which may have been approved to the standards of ISO 9001:2008. Such a company will always outperform a local fabrication shop and an overenthusiastic salesman.
Whomever you choose as your heat exchanger manufacturer, a partnership should develop. Someone needs to spend time with you, to help you find the optimal solution, and then follow the project through to completion ultimately helping you exceed your expectations.