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Discussion Starter #1
So I am reading in the installation instructions for all Goodman CAPF cased coils, and I come across this--


NOTE:
The cased coil MUST be installed with the line set and
drain opening to the FRONT of the furnace.

The "note" part leads me to ask--Why MUST this be done? I had planned to have the parts facing opposite directions. There is plenty of service access space front and back.

I can see that the coil is not quite symmetrical front to back. But it is very close to symmetrical.

And the furnace has the usual set back of the plenum opening to allow for the intake and exhaust tubing of a high efficiency furnace. This provides a somewhat protected space above the furnace for the line set and the drain lines.

Is there any other reason--like a Code requirement?
 

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All high efficiency furnaces are installed sloped slightly to the front to drain the condensate , so your coil needs to work with this slope or it won't drain properly. I recommend an open tee on the drain connection for the coil, to work as a vacuum break. The air velocity thru the coil can sometimes interfere with the naturally siphoning of the drain.
 

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Discussion Starter #3
All high efficiency furnaces are installed sloped slightly to the front to drain the condensate , so your coil needs to work with this slope or it won't drain properly. I recommend an open tee on the drain connection for the coil, to work as a vacuum break. The air velocity thru the coil can sometimes interfere with the naturally siphoning of the drain.
I am honored to be the recipient of your 1000th post.

In my case, all of the measures necessary to make sure the condensate drains properly are taken care of nicely inside the furnace by the design of the heat exchanger, condenser, condensate collector, and condensate drains. I am pretty sure all of these would work adequately even if the furnace were installed 10 degrees off plumb in any direction.

And the AC coil drain pan has quite a bit of slope--toward the condensate drain--designed into it to take care of water removal. This could tolerate a bit of off-plumb, but I believe it will work best if the furnace and coil are straight up and down.
 

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ALL high efficiency furnaces should be sloped about 1/2 inch to the front as recommended by the manufacturer. I had lots of trouble with a York unit where the water hung up inside the secondary coil and would cause nuisance pressure switch tripping. Not much slope is necessary but some is. They don't build that into the furnace unfortunately. You may want to call Goodman and ask them why they have that statement. When an A coil is installed the installer creates the slope but I suspect they are concerned that case coils cannot be manually sloped by the installer.

Good Luck
 

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Discussion Starter #6
ALL high efficiency furnaces should be sloped about 1/2 inch to the front as recommended by the manufacturer. I had lots of trouble with a York unit where the water hung up inside the secondary coil and would cause nuisance pressure switch tripping. Not much slope is necessary but some is. They don't build that into the furnace unfortunately. You may want to call Goodman and ask them why they have that statement. When an A coil is installed the installer creates the slope but I suspect they are concerned that case coils cannot be manually sloped by the installer.

Good Luck
You got me curious, so I measured the furnace secondary coil slope. On my Goodman furnace (a GMV 115000 BTUH) the secondary coil is 1 inch lower at the front side, compared to the back side. The coils run right to left, and are at the same height right and left.

Is this what you meant by "They don't build that into the furnace unfortunately."?

As for my A coil, the mounting support rails inside the case are level. The drain pan bottom--where the water collects--is sloped downward toward the drain holes, with the high point at the corner opposite the drain holes. The top surface of the drain pan that the coil rests on is level. The top of the coil is level, and the A-sides are plumb. There really is no space inside the case to tilt the coil.

I believe that this same coil from Goodman uncased uses the same drain pan. So the proper install in a different case or a plenum would call for level side supports.

Perhaps Lennox and others might want to copy some of the engineering from Goodman.

But we have gone off-topic here. Does anyone know why the Goodman instructions are so adamant about having the AC line set facing the same direction as the front of the furnace?

My two best gusses are (1) there is something specific about the nature of the air discharge from a Goodman furnace that works better with this orientation, or (2) this text is left over from a bygone era. With a high efficiency furnace and an AC unit facing the same direction, you have vent pipes, refrigerant lines, and drain hoses competing for space. And the vent plumbing has to be removed to change out the A coil.
 

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The info I post is for everyone else who reads these posts plus you. As a servicetech real life experience is what makes these units work. I used to sell Goodman and know all about them. The latest batch are pretty good.
 
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