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[Corngrinder]

Hi, I'm new to the forum, but love all the discussion and topics available.  I'm sure something regarding this question has already come up, but due to the countless pages of threads I'm unable to find an answer.

I have a modular home (the pre-fabricated kind) with a down-flow furnace.  Inside my HVAC system, the fan sits on top.  Directly below the fan is an enclosed space, roughly 16" from top to bottom and the width of my HVAC system.  Under this is my furnace (it's gas), and directly under that is my a-coil. There is about 1.5" between the bottom of my furnace and my a-coil.  Under the a-coil is my floor level, and under that my ducting branches out to the various rooms of the house. 

I need to install my water-to-air exchanger somewhere in this system.  The easiest way I can think of is to cut into the 16" deep "box" that sits under my fan.  However, I'm not an expert in this matter and don't know if that box serves a purpose or it is just there as a cold air (or something like that) plenum.  My other option is to lift the furnace up, by cutting the 16" box and putting the furnace closer to the fan, then installing the exchanger under the furnace and above the a-coil.  A third option of installing the exchanger under the a-coil is out of the question; there is simply not enough space between my floor and the bottom of the a-coil. Furthermore, option 3 would require me to complete all steps necessary to accomplish option 2 and therefore be unnecessary.  Also understand that option 2 would require me to reduce the size of the 16" space under my fan.

So, finally to the point - does anyone know or have first-hand experience in this regard?

NOTE: Manufacturer of my exchanger merely suggests that the unit be installed after the fan. My dealer suggested installing somewhere between the fan and the a-coil (hence option 1 and 2).


Please help.  All suggestions are welcomed and appreciated.

[mlappin]

I can point the exact thread out, but I do recall several people saying they installed their HX before the fan.

[Corngrinder]

Installing before the fan is, of course, an option, but I fear the negative effects of all that hot air being blown through my fan.  That's just an added headache down the road if I'm not mistaken.

[Jwood]

If it will fit on the supply side of the fan put it there the return side is option 2 if the supply side won't work.

[Corngrinder]

I've recently talked to an HVAC installer (friend of a friend) and he said it was okay to put the exchanger inside the 16" box I had mentioned in the original post.  The 'box' is called a draft hood, by the way.  If you were to do a Google image search for a 'Coleman downflow gas furnace', you'll find an illustration of what I'm talking about.

Thanks to all who lent advice.  Hopefully this thread will also help other members who may have been confused like I was.