No plenum

I have never seen this done, no plenum above the A/C coil, will it operate properly?

Not likely :slight_smile:
Consult manufacturers installation instructionsfor minimum plenum size.

Must have been a small place with no branch ducts.
Interested to see what Charlie says.

Thanks, did not think it was a proper installation.

Looking around many guys seem to think it is not a big deal while some say it affects airflow or air speed through the filter ,etc.


Two furnace Mansard tomorrow and hope nothing strange like that .

I would have to say its not a standard installation appears to be a novice. It is not recommended to install the ducts on the end cap. The plenum should transverse the ceiling above and the ducts attached to the sides of the plenum not the end cap. How was the return was it a local return or was there a return plenum with duct

Most of the coil is blocked off, so there won’t be a lot of heating or cooling, whatever it is supposed to be doing.

The return air is OK, duct with one grill high and and one low. on the wall about 6’0" from the unit. 16X25X1 filter.

I was once told the the ducts should start 6" down from the top of the plenum to get proper air mixing.

The blower discharge should discharge against the end cap of the plenum and build static pressure within the plenum. I have never heard of the 6 inches down from the plenum end cap but it sounds reasonable just as long as it is not on the end cap. In special cases where a duct must be on the end cap it should have a damper installed for balancing

Thanks Charley

bad deal. Too tired to explain. You could sit in a class of mine in about 3 weeks and learn all about the airflow restristions and problems there. As for the magic 6" rule throw that out along with “step down supply trunk one size for every 10 feet long”. There’s a little math involved and physics at play

A good idea is to go to the control panel and list who and where you are so we all know your location and web site . Thanks … Roy

Tim may not get your message. I just figured out how to get notifications of replies, and even with that, it doesn’t always work. I would PM, to be sure, in addition to the post. Could be useful to someone.

It’s a big Message Board :slight_smile:

No it will not work right.

As for distance, is about the number of duct diameters before the takeoff, not a measured distance. See SMACNA Standards.

Is it condensate drain tapped into the sewer pipe?
I don’t care if it is a condensate pump, it’s not allowed.

Look again its not the sewer pipe:p;-)

Vent stack? That’s wrong the also, no?

Let me go get my glasses…

The fitting is a 90 looks like it connects to the C air or the flue discharge can not tell from here but it don’t look like a vent stack;-)

I would “guess” that that is the condensate drain off for the flue.

It is supposed to drain the pipe into the “furnace” condensate trap (internal).

Not likely to drain off a vertical riser, will it?

It’s a 90+ furnace, the with PVC is the flue, the condensate is in a floor drain with a trap.