I am installing a 4 ton packaged heat pump into my double wide. These homes have two main tunks which run parallel and have the same size floor registers in every room. The supply from one branch to the other is a single 12" flex that runs from directly under the discharge of the airhandler into the other branch. Here is my question: As I install the new unit what is the proper size of supply into the two trunks?? 18" into a distribution with one 14" out and suppling each trunk - that is my guess, but what is correct in these conversions? If you have worked on these you know that the existing duct is duct board approx 12" x 6". Each trunk feeds 6 registers. Thanks for the help.
Last edited by w-s_1; 10-16-2007 at 01:59 PM.
Reason: clarifify home style
Found this answer from a local pro who is actually friendly and not money hungry - he did the math and my current total of 12" lines only provide slightly more than 500fps which is not nearly enough. A simply reduction to 10" flex will take the fps to mid 700's with my unit and set up. Made these changes and the work is paying off.