Could someone enlighten me on a couple things. First we are looking to replace our condensing unit and air handler. Ours was installed in 83 so it has had a good life. After looking a some different units online just for price ideas I have noticed that all newer models these days come with the coil on the bottom and blower on top. Looking at a couple of my friends furnaces theirs are like mine, with the blower on the bottom, controls on top, and the coil in a fabricated plenum. Does any one know why the coils are on the bottom on newer units?
I'm trying to find a system that will allow me to put my return duct into the left side of the unit insted of coming up through the bottom of the air handler. I've notice in a couple install manuals that I downloaded that alot of handlers have the return air coming up through the bottom. Are these things that have just changed over the years?
Anytime you see a unit with the coil on the bottom and the blower on top, this is a "counterflow" unit. Basically its blows the air down into under the floor ducting rather than up into a plenum. As for bringing your return air into the left side, all units allow for left, right or bottom return air applications. These will have to be cut in manually for the application you have. You CANNOT cut a return air into the back of the unit however, as there isn't sufficient area for the volume of air required on the back. As for your new A/C system, there have been a few industry changes in the last year or so. For 1 your old system ran on R-22 (Freon) refridgerant. As of Dec 31, 2010 these systems are no longer manufactured, so most companies are proactivly installing the new R-410A systems. These require replacement of the entire system, condensor, evaporator coil and line set. Gov't regulations also called for more efficient systems. As such, the easiest way manufacturers have been able to increase efficiency was to increase the coil sizes, allowing more heat transfer. I mention this to ensure you can check you have enough space above the handler to acommodate the taller coils.