Enough return air for existing heating system

[resjan]

How do I know if I have currently enough existing return air capacity for a 2.5 ton air handler system in laundry room? This is not a standard return ducting system and may be hard to explain well, but tried below. Basically, trying to analyze what I currently have. I want to make sure have enough return air capacity feeding into current air handler.

5 return registers feed into a T shaped return area (hallways for bedrooms) that then feeds into 3 return openings (no air restriction) that then goes into a 12 high x 24 wide x 32 long return area(laundry room) which feeds a 18.5 wide x 18.5 Deep x 20 inch high metal return plenum and then a 20 x 20 x 4 filter set up on top of air handler (downflow application)

Return registers - 4 bedroom with 7.5x11 stamp faced grilles (1/4 inch gaps) and 1 hallway- 9x21 grille that is basically a piece of plastic with 1/2 in x 1/2 in openings

Main Return area – is a lowered ceiling T-shaped since we are on a slab and is 12 inch High by 36 wide. Stem of T is 15 Ft long that has the big grille and the cross is 20 feet long and has the 4 bedroom return grilles.

The 3 return openings that go into return plenum are 6x18, 6x14, 6x14. These are wide open with no grille restrictions.

[beenthere]

I think pics would make it easier to know what you have.

[dan sw fl]

How do I know if I have currently enough existing return air capacity for a 2.5 ton air handler system in laundry room?
This is not a standard return ducting system and may be hard to explain well, but tried below.

Basically, trying to analyze what I currently have. MEASURE THE TOTAL AIR FLOW RATE
I want to make sure have enough return air capacity feeding into current air handler.

2.5 TON A/C = 900 to 1,000 CFM is required
if you are located below 3,500 Foot Elevation. > 1,000 CFM, IF > 5,000 FT.
No ZIP _ _ _ _ _ is provided.


TAB may be necessary along with ACCA MANUAL J ROOM-BY-ROOM CALC.

[resjan]

I knew it would be hard to explain. Do I have enough posts to be able to post pictures?

I do not understand what Dan sw fl is saying in his post. I am in northern ohio.

I am just a homeowner and wanted to try to verify myself by seeing if I could do it by total area, # of openings, and # of grills, etc. since I have been told yes, but no firm calculations provided to me.

[dan sw fl]

Anticipated TEM6 AHU Performance

Previous Thread by OP:
____________ CFM air flow higher than performance table
2.5 Ton 14 SEER Heat Pump

https://www.trane.com/content/dam/Tr...N_08152017.pdf

__ TRANE
TEM6 AOB 030

PAGE 4
______ 1/3 HP MOTOR

PAGE 8 - TABLE 2
_____________ 2.5 TON Setting @ 0.9" TESP = 872 CFM

I don't know the VOLTS & AMPS measured on the AHU.
_ NORMAL AIRFLOW SETTING: _ 325 Watts at 0.9" W.C. ESP is exceeding a 1.0 Service Factor for a 1/3 HP Motor

[resjan]

Dan,

Please explain in words. What you provided tells me about the air handler and static pressure, but not the capacity.

I just want to know the capacity of my return area that feeds into the air handler based on what I stated in my original post.

I have this large return area in my house and want to know how much airflow it is capable of handling.

[timjimbob]

You can measure static pressure drop, but this will tell you if you dont have enough. But it also depends on total system ductwork. With RA, more is better.

[resjan]

beenthere,

Here are pictures

[dan sw fl]

Dan,

Please explain in words.
What you provided tells me about the air handler and static pressure, but not the capacity.

I just want to know the capacity of my return area that feeds into the air handler based on what I stated in my original post.

I have this large return area in my house and want to know how much airflow it is capable of handling.

If the Existing TESP is > 1.0" W.C.,
the AHU capacity would be ~ high 700's or low 800's CFM
given a Rough extrapolation of the highlighted Table 2 data.


An A/C unit air flow rate capacity is NOT determined by the amount of return duct work.

ALL INFORMATION ABOUT ALL SUPPLY AND RETURN FLOW PATHS AND EVERY DUCT / connection COMPONENT
IS REQUIRED
TO DEVELOP AN ACCURATE ACCA MANUAL D CALCULATION.

SIMPLIFICATION:
If all the SUPPLY ducts are 5" Diameter, 20 foot long Flexible ducts
that are NOT properly STRETCHED, the OVERALL duct capacity
may be ~ 10 to 12 supply branches * ~ 60 CFM Each = ~ 700 CFM.

I Do Not Have upto ~ 2 Days free time to determine
what the ACTUAL Problems are and the EFFECTIVE resolutions.

EMBEDDED duct schematic [ specifically an applicable Downflow arrangement ] would be about 1/3 of the information needed
to evaluate an existing duct layout.

[pecmsg]

How do you get return air ducts where Headers should be?

[resjan]

Pecmsg,
what to you mean by headers?

[pecmsg]

*

Pecmsg,
what to you mean by headers?

[resjan]

all homes in our development have this type of return ducting. It is basically a big drop ceiling that is 12 high by 36 wide and encompasses the hallways leading to the bedrooms for a total of about 35 feet in length (T shaped). I guess since this is a slab, they needed to put return ducting somewhere and chose to use this type system for the return system.

[comfortdoc]

it would be best to have a competent technician measure the static pressure and using the airflow performance tables determine the current airflow.

[BNME8EZ]

As I read it I think the hall ceiling was lowered, all return grill dump into the lowered ceiling area then there are 2-6x14 & 1-6x18 openings going from the lowered ceiling area through the wall into the return drop.

As I measure it the area going into the return drop should be ok, the lowered ceiling should be the same but the grills/openings may be suspect.

[resjan]

BNME8EZ

You are correct. That is exactly what is happening and the type of answer I am looking for.
Just wanted to be sure. I do not hear any noise coming from the 5 return vents, but the 4 bedroom vents I could see if I could get larger grille if needed.
I am just trying to get some additional feedback since I still ultimately believe something is wrong with the air handler itself from my previous post.
My neighbor concurs with me since he has a Trane VS (older thought) with same return system, but his unit on 2.5 normal is much quieter at the unit as well as air flow in ducts much quieter and lower. He also has 10 individual runs like my house.

[BNME8EZ]

Simple test, pull the grills off in the bedrooms, see if anything changes, if it does great yo have a direction to pursue, if it doesn't your not wasting money on new grills that may not help.