Air handler not pushing enough air

Doc Holliday · 04-16-2012, 02:33 PM

Quote:

Originally Posted by ryanxo

Well I figure Texas is hot as crap in the summer and can get pretty cold in the winter too so you all prolly know what you are talking about and if it works better than the crap I have going on now then I'm all for changing it up.

I have been told it's a 2 ton system.
I have done research on this style of duct system and they call it a Reducecd extended plenum duct system.
Apparently the plenum goes a certain distance then steps down a size as vents are run off of it.

I would love to be able to do a shorter plenum. It would make maneuvering around the attic alot easier.

You have a how to or some diagrams somewhere so I can maybe design a better configuration.

I'll work on all the details of that analysis today.

2 ton? You kidding me? What size trunk line is it from there it starts off? And how big are those duct take offs/flex duct lines?

Judging by the size of that trunk, the length and the size of the ducts your trunk line would be for something like a 7.5 ton minimum.

Let's say for each single ton you push 400 cfm. That would mean, and I'd have to ge out my ductulator and do some real research for the exact numbers, you could only use something like TWO 10" flext duct at best. That is all the air that system can push.

How many lines of what size duct is on that right now? No wonder you have no air.

http://efficientcomfort.net/Rules_an...ct_Systems.pdf

ryanxo · 04-16-2012, 02:39 PM

Quote:

Originally Posted by Doc Holliday

2 ton? You kidding me? What size trunk line is it from there it starts off? And how big are those duct take offs/flex duct lines?

Judging by the size of that trunk, the length and the size of the ducts your trunk line would be for something like a 7.5 ton minimum.

Let's say for each single ton you push 400 cfm. That would mean, and I'd have to ge out my ductulator and do some real research for the exact numbers, you could only use something like TWO 10" flext duct at best. That is all the air that system can push.

How many lines of what size duct is on that right now? No wonder you have no air.

http://efficientcomfort.net/Rules_an...ct_Systems.pdf

There are 10 flex duct lines.
8 are 6 inches.
2 are 4 inches

Isnt the rule 1 ton per 600 square feet? That's what I was told.

According to that PDF. "A 2 ton system should have 10 or 11 outlets"

Doc Holliday · 04-16-2012, 02:41 PM

Quote:

Originally Posted by dcastillo

Im definitely not an AC expert....but wouldnt a 1344sqr ft house need more then a 2 ton system?

Rule of thumb only from the older days of less efficient systems such as the Trane XR11 woud be 500 sq ft per one ton. Btw, efficientcy means energy consumption, not that it won't produce cold or hot air, just that you pay more for it on your elecrical bill.

Nowdays, around here at least, they say 600 sq ft per one ton with insulation and envelope being so much better than the old days. Again, just a simple rule of thumb and not the correct or scientific way to size an hvac system to a structure.

Better to be slightly undersized than slightly oversized for dehumidification factor, heat intensity of the air molecules. A 72 degree air molecule with high moisture content (humidity) will feel hotter and stickier to the skin than a much drier 72 degree air molecule due to less moisture in the air.

In other words, a/c run time needs to appropriate enough to dry the air as an a/c system is a dehumidier. A bigger or oversized system will shorten the run time as it satisfies the stat quicker. Not good.

Doc Holliday · 04-16-2012, 02:45 PM

Quote:

Originally Posted by ryanxo

There are 10 flex duct lines.
8 are 6 inches.
2 are 4 inches

Isnt the rule 1 ton per 600 square feet? That's what I was told.

According to that PDF. "A 2 ton system should have 10 or 11 outlets"

Funny, it all looks so much bigger in the pic, like they're 10's and 12's.

Perhaps if they are very small 6" duct lines. It's actually not the amount of lines you have but the combined total cfm the system has to offer and how you disperse it, with the correct sized ducts leading to a room of equal cfm requirement.

Doc Holliday · 04-16-2012, 02:47 PM

http://www.alpinehomeair.com/related/Ductwork.pdf

Doc Holliday · 04-16-2012, 02:53 PM

http://www.udarrell.com/proper_cfm_b...g_systems.html

ryanxo · 04-16-2012, 03:01 PM

Quote:

Originally Posted by Doc Holliday

Rule of thumb only from the older days of less efficient systems such as the Trane XR11 woud be 500 sq ft per one ton. Btw, efficientcy means energy consumption, not that it won't produce cold or hot air, just that you pay more for it on your elecrical bill.

Nowdays, around here at least, they say 600 sq ft per one ton with insulation and envelope being so much better than the old days. Again, just a simple rule of thumb and not the correct or scientific way to size an hvac system to a structure.

Better to be slightly undersized than slightly oversized for dehumidification factor, heat intensity of the air molecules. A 72 degree air molecule with high moisture content (humidity) will feel hotter and stickier to the skin than a much drier 72 degree air molecule due to less moisture in the air.

In other words, a/c run time needs to appropriate enough to dry the air as an a/c system is a dehumidier. A bigger or oversized system will shorten the run time as it satisfies the stat quicker. Not good.

The XR11 is an older system? Dang i thought it was newer. How old is it? Maybe it's time for a new one while I'm at it.

Doc Holliday · 04-16-2012, 03:07 PM

If I'm not mistaken Trane prints the date of manufacture on their equipment data plate/sticker. American Standard and Trane are one and the same, why I'm posting the pic.

ryanxo · 04-16-2012, 03:27 PM

Ok I have a pic of my air handler label that I took last year.

Looking at the manufacturer date now the air handler looks like it says 90 something but I know the outdoor unit was either 2007 or 2009 so that means they don't match I guess. Awesome! << Sarcasm

The pic is huge I'll resize it and add it later...

Doc Holliday · 04-16-2012, 03:35 PM

Post the model numbers of both the inside air handler and the outside condenser. The size will be in the model number.

**beenthere** · 04-16-2012, 05:03 PM

Quote:

Originally Posted by dcastillo

Could I check and see if its running slow by reading the current draw to the motor? (with a Clamp meter)

Or is there another way to verify the motor is running at full (proper) speed?

thanx
Danny

I usually just look at them. Seen enough to pretty much know by sight if its running slow or not.

If its bearings causing it to run slow, then the amp draw will be high.

ryanxo · 04-17-2012, 06:30 AM

Indoor Air Handler:

American Standard Inc.
Model: TWE024C140A0
Serial: N3234X11V
Motor HP: 1/4
F.L AMPS 1.7
Volts: 200-230
MFR Date: 08/96 << I think its hard to read. I know it's 90 something
I took a pic of the outdoor one but apparently it didn't save on my phone. I know it's XR11 tho.
Aha found the model #: model: 2TWR1024A1000AB
Checking my notes I wrote down that the outdoor unit was 6 years old and this was last year meaning it is 7 years old now.
Aka manufactured year: 2005

I used the indoor model# to do some searching and found this other thread on a HVAC forum. The fellow was having the same issue where the air flow out of his vents was just a trickle and he could barely feel it. The issue turned out to be the main control board.... "After many (good) limit switches being changed, the repair company finally replaced the main control board and the furnace is back to working as it did after it was initially installed."

Could that be an issue with mine? When I first got the house the attic fan didn't work so it was pushing 140+ up there during summer days... It could have easily burnt something up.

dcastillo did you check out things at your rental last night? Any updates? I'm still hoping our findings overlap and fix both of our issues.

Doc Holliday · 04-17-2012, 12:15 PM

Of course it could be. All you need is an electrical meter to check the voltage being applied through the board to the motor.

I think I've already stated that on here somewhere, to check voltages.

dcastillo · 04-17-2012, 12:18 PM

Quote:

Originally Posted by ryanxo

dcastillo did you check out things at your rental last night? Any updates? I'm still hoping our findings overlap and fix both of our issues.

Nope...
Love how the tenant complains about the AC, but cant seem to find time for me to come take a look....

-Danny

Doc Holliday · 04-17-2012, 12:24 PM

Quote:

Originally Posted by dcastillo

Nope...
Love how the tenant complains about the AC, but cant seem to find time for me to come take a look....

-Danny

Ha! I was out in BFE Conroe, about 65 miles from where I live, on a service call. The home owner was talking to me on the phone, the tenants had a very difficult time waking up to let me in. I was banging and banging on their door and windows as I knew they were there, their vehicle was on the driveway.

Said their a/c was out for over a week and she, the landlord, had other people there to try and repair the problem but the tenants would never wake up to let them in.

Go figure.