Replacing air handler - How to fit when form factors are slightly different??

hennyh

I'm planning a project that involves replacement of an air handler.

The outlet (base) will fit perfect. However the new air handler is 3-4" lower then the unit it is replacing and the inlet is 19.5 X 19.5. My return air plenum is 20.5 X 18.5.

Here are my questions:

1. What is the professional way of modifying the existing plenum to new air handler. I assume making a custom sleeve out of galvanized sheet metal is the best approach? What about insulated duct board? Is fiberglass tape and mastic the best seem method? How do professionals in the field handle slight form factor differences?

2. The new air handler will set on top of a sheet metal base. I assume that some form of gasket or sealant should be used where the air handler bottom contacts the base. What is the preferred method of sealing the contact of these two surfaces? Or is it even done?

I'm striving to do things using the best known industry methods and practices vs. the duct tape method.

I've also observed some other installations where it looks like they used some form of flexible material (almost like canvas) to mate the air handler to plenum.

#CARRIERMAN

Hi hennyh

The best way to make your transition is have a sheet metal shop build it. If your system is over head I would definatly reccomend the use of a canvas joint. The canvas joint's job is to stop vibration of the unit from resinating into duct work and the living space. Keep in mind a good sheet metal shop is not going to be cheap, you are paying for craftsmanship. The cheap way out but not by any means a permanent solution is duct board, its easy, its fast, and it doens't last very long. As for sealing the base to the air handler, the best solution for that is a high quality silicone, it will stay pliable for years and will generally adhere well to the metal surfaces. Hope some of this made sense for you.

Good luck
Rusty

hennyh

It sure did. Thanks for sharing your knowledge!!