Advice - AC Coil extending past plenum
This week I had my new furnace and AC installed.
I have a concern that the AC coil extends 5.5" from the plenum.
I know that was an issue with my previous system and am having a hard time seeing how I am getting full benefit of the AC with a portion of it extended from the air flow.
I am by no means a HVAC expert, so if this is normal and there is no impact to the system cooling efficiency then I am fine. However, if there is an impact do I need to look at a bigger plenum?
My preference is to have the system running at it's peak and not hampered in any way.
I'm hoping that the pros here will let me know what their recommendations are and why.
A picture would be most helpful.
Yes. We don't know if the OP is talking about a horizontal unit in the attic, or an upflow unit in a hall closet, or one or the other in a basement/crawl space.
Originally Posted by nvr2old
Generally speaking, it is best to not intentionally blank off a section of cooling coil, as some installations do. This is what transitions are for should the coil be larger than the air handler or furnace dimensions.
- Electricity makes refrigeration happen.
- Refrigeration makes the HVAC psychrometric process happen.
- HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.
A building is NOT beautiful unless it is also comfortable.
Do you mean the AC coil box is wider than the plenum? If so, that's OK, you just don't want a coil box that is narrower than the plenum or furnace as that would cut air flow down significantly.
A good HVAC tech knows how, an educated HVAC tech knows why!
This has become a problem with the higher SEER coils & lack of room, etc. to make proper retro adjustments.
The main thing is that the entry through the coil be open to a straight stream of airflow. Also, the drain pan, if not insulated, may sweat if out of the air stream.
It is very important to have equal distribution of air through the coil circuits.
Unequal distribution will result in lack of liquid evaporation which affects suction superheat.
Due to a colder line, a TXV would tend to reduce the flow of refrigerant to the coil.
Charging by superheat will also be OFF. Both superheat & subcooling should always be checked on all systems & compared to what they should be.
If at all possible have the retro work done to correct any airflow problems.
Will take pics tonight and post them.
I'll try to explain it further...
Basement install (Toronto, Canada).
Pics will be uploaded tonight when I get home
| | Plenum
| Coil |
Hmmmm.......... It looks like the coil is offset from both the furnace and the plenum airflow and not uniformly extending out on all 4 sides. This could be a problem. Post pics!
Here are the pictures....
Please provide your feedback.
Those should go on the wall of shame, that is not right, won't work right, words cannot describe the my shock when i saw these pics.
Wow. Wall of shame is right. Someone did some poor work for you there.
"Hey Lama, hey, how about a little something, you know, for the effort." And he says, "there won't be any money, but when you die, on your deathbed, you will receive total consciousness." So I got that goin' for me, which is nice. - Carl Spackler
Just when you thought you've seen everything.
It does look as though the coil was already in that position before the new furnace was installed. and they just transitioned to it as the new furnace is shorter. Even if it was that way, the installer should have mentioned that its improper.
You should get a new cased coil installed on the furnace ( matched to the furnace opening ). The manufacturer of the furnace will have a matching enclosed coil set up.
I'll be there when I get there and not a minute later
wow...if I did that i would be fired.....lol