Regular furnace set up backwards.....

[kurt]

Standard furnace, combustion on bottom, heat exchanger up next, AC coil plenum, etc. But they set it up so it's counterflow....air flow is top to bottom, so in effect, it's the return air being conditioned. Also, the cabinet doors are backwards. I reinstalled then with the vented portion at the bottom to supply the combustion.

I've never seen, heard, or imagined anyone ever doing this. Besides from the complete stupidity, what else can go wrong? It's so wrong I'm not even sure what that means or how to describe it..... Anyone ever seen this?

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[Marc]

If that's the blower on top then the airflow is not in the direction of the arrows.

Air enters at the center of blower cage, exits along its outer perimeter.

A lot in that picture still confuses me though, so I could be wrong about it all.

I've seen a fair number of downflow units.

Marc

[kurt]

The blower is "on top"; the doors are set up wrong. Air flow is absolutely downward. I checked it several times because I couldn't believe it. I see plenty of counterflow furnaces; this is an upflow furnace they converted to counterflow. I don't know why.

Combustion on the bottom, blower in the middle, AC plenum on top of it all. It's the return air that gets conditioned. As far as pushing heat and cold air, it does that. It's just setup ass backwards.

They took a standard furnace and converted it to counterflow. It's wrong, it works, I'm not even sure how to describe it intelligently.

[Jim Katen]

. . . Besides from the complete stupidity, what else can go wrong?

The classic fear is that a refrigerant leak at the evaporator coil can allow refrigerant to hit a hot heat exhanger and convert to an unpleasant (if not unhealthy) gas.

Also, if the evaporator coil's condensate collection system isn't working properly, the blower can suck up the water and spray it all over the heat exchanger, accelerating corrosion.

[inspector57]

If that's the blower on top then the airflow is not in the direction of the arrows.

Air enters at the center of blower cage, exits along its outer perimeter.

A lot in that picture still confuses me though, so I could be wrong about it all.

I've seen a fair number of downflow units.

Marc

I think you are looking at the humidifier. The blower is not actually visible if I followed the description correctly. (I had the impression that was the blower at first due to the duct from the side)

[inspector57]

. . . Besides from the complete stupidity, what else can go wrong?

The classic fear is that a refrigerant leak at the evaporator coil can allow refrigerant to hit a hot heat exhanger and convert to an unpleasant (if not unhealthy) gas.

Also, if the evaporator coil's condensate collection system isn't working properly, the blower can suck up the water and spray it all over the heat exchanger, accelerating corrosion.

It seems I remember a requirement that the coiling coil be located down stream from the furnace but the only bad outcome I can think of is accelerated corrosion.

[Jim Katen]

. . . Besides from the complete stupidity, what else can go wrong?

The classic fear is that a refrigerant leak at the evaporator coil can allow refrigerant to hit a hot heat exhanger and convert to an unpleasant (if not unhealthy) gas.

Also, if the evaporator coil's condensate collection system isn't working properly, the blower can suck up the water and spray it all over the heat exchanger, accelerating corrosion.

It seems I remember a requirement that the coiling coil be located down stream from the furnace but the only bad outcome I can think of is accelerated corrosion.

In the bad old days R-12 impinging on a hot heat exchanger could actually produce phosgene gas. R-22 doesn't produce phosgene, but it still produces some very unpleasant gases when heated. I don't know about 134a.

[mjr6550]

I'm confused. Why is it not a downflow furnace with the AC coil on top?

How would you do this with a standard furnace?

[kurt]

I was confused too. It's a bunch of different parts that someone cobbled into a down flow furnace with the AC coil on top. I was so goofy, I didn't know what I was looking at, and it's now clear that confusion was an appropriate response.

They're going to put in a new furnace. Problem solved.