House Not cooling in the afternoon.

[texastitan]

I live in houston. I have lived in this house for approx 3 years. I noticed last year that my A/C was running all day long. It was toward the end of summer and I had it charged. Dont remember was it was charged to. Now this summer its doing the same thing. When the temp outside gets to the high 80's my A/C keeps going. I also remember installing a digital thermostat last year. Could this be a problem. It reads the correct house temp on its display. I ask about the thermo because my system is supposed to be a dual speed and wonder if it affected it somehow. The thermostat that was in the house was a old POS anyway. just a turn dial type. I am told that I have a 3 ton unit. Rheem/ criterion gas furnace upstairs. Tempstar 2400 outside. House is approx 1800 sq ft. The temp drop is pretty good out of the registers. Attic is pretty well insulated. Coil looks clean. the return air sucks pretty good. I can close the door to the farthest room in the house and feel the air get sucked from under the door. Any help or idead would be appreciated.

[Mr Bill]

If you have a two speed compressor and do not have the right stat it can effect your system performance, but I live in Houston also and I would just imagine at the temps we have had lately the only time it would see the lower speed would be about 5:00 am in the morning, maybe it's just low on charge again, did the prior service company get into any detail about how low it was or even see were the leak might be? or was it just a charge and go? and has it been ok up until now?

[Edited by mrbillpro on 06-25-2005 at 11:36 AM]

[texastitan]

It was charged last year about 3 pounds maybe? I had it checked again about a week ago and it took minimal charge. If it has a leak its minor. The The hvac guy didnt see anything wrong off hand that was bad. I wanna say after about 1 in the afternoon it continualy runs till about 830 900 at night. I have even taken my filter out of the return to see if its a too restrictive filter. no help. I was told also it might be a slightly undersized unit. I can swear the first summer here it worked fine.

[Mr Bill]

In my personal opinion heat load or no heat load, I live in Houston and you would have to have r-100 insulation everywhere and no windows for a 3-ton to cool 1800 sq. ft.

[bbk]

1800 sq.ft. is where we usualy wind up going from a 3 1/2 ton to a 4 ton up here around Longview.

[coco]

here in minnesota 2400 sq ft we put in 2 .5 tons and they work great 20 degree td on a 95 ambient w/ high humidity

[coco]

r-22 40 ft linest 5/8 3/8 9 7''r/a 17 6'' s/a

[Mr Bill]

Originally posted by coco
here in minnesota 2400 sq ft we put in 2 .5 tons and they work great 20 degree td on a 95 ambient w/ high humidity

Hey we here in Texas are happy for you but you dang sure won't get any 2.5 ton unit to cool 2400 sq. ft. in Houston Texas unless you are installing it in a cave take my word for it been in Houston 54 years and been in this Business for 28 years. If you minnesotians have a trick to make a 2.5-ton a/c work in 2400 sq.ft. at higher humidity conditions could you please sell me your idea? I could make millions in Houston by saving my customers millions.

[hiltontech]

I'm not far from Houston, I live here in hot Louisiana and 2400 sq. ft. home requires a 4 ton unit, a 3 ton unit just won't cut it, if you had a 4 ton you wouldn't have the problem your having now,but being you have a smaller unit than you should have raises questions on how to fix your problem, maybe adding a large window unit in the largest part of your home would help out.
Tough call here.

HiltonTech

[dan sw fl]

Originally posted by texastitan
I wanna say after about 1 in the afternoon it runs continually till ~9.
I was told also it might be a SLIGHTLY undersized unit.

Sounds About NORMAL to me.

What's the attic Temperature?
How much duct is in the attic?

Can you maintain < 78'F at 53% relative humidity?

"Temp drop pretty good" .. does that mean air diffusers temperature is < 60'F.

Any Windows on the WEST side.
TOTAL AREA? ___ SQ. FEET
Tinted? IF not, have a PRO add film.

If you have 100 Sq. feet of Glass on the West side
with CLEAR windows, adding film will save
~3300 BTUh equipment capacity or 1/4-Ton.

Then a SLIGHTLY Undersized 3-Ton A/C for 1,800 S.F. HOUSTON Residence will only run Continuously from 1:20 PM to 7:15 PM.

[texastitan]

Ill fill in the blanks for you sometime today, thanks for the help!

[coco]

new construction , very tightly insulated homes , master of airflow

[coco]

wow i never thought about such large a/c 's down south we it takes a 4-5000 sq ft house to get 4 or 5 tons of cooling in mn

[dpatty]

Originally posted by coco
wow i never thought about such large a/c 's down south we it takes a 4-5000 sq ft house to get 4 or 5 tons of cooling in mn

Your homes up north are designed for severe temp differences in the winter being the reason yo can cool maybe up to a 3000 sqf home with a 2.5 to 3 ton ac. Just for kicks someday recalculate with wall insulation of r11 and cieling insulation of r19 and see the difference.

I use the 600sqf per ton for estimating only. All of my homes are manual j calculated before quotes are given. In the Tyler Tx area I have homes of about 1800sqf with 2 to 4 ton systems. most get a 2.5 to 3 ton on new construction and 3.5 and 4 ton on older less well insulated homes

[coco]

55 years of company experience my boss knows in 10 seconds what size furnace and a/c w/o manual j

[slice]

This question was most likley asked a week ago when our heat index was up around 105*, My own a/c at home would do the same thing, As far as 1800 sq ft per 3 tons is 600 per ton, in new construction here that would be called okay. not exact but close..

[dpatty]

Originally posted by coco
55 years of company experience my boss knows in 10 seconds what size furnace and a/c w/o manual j

After 55 years I bet he would know what will get it done.

[hiltontech]

"As far as 1800 sq ft per 3 tons is 600 per ton"

I misread, I thought it was 2400sq. ft.

3 ton is about right.

[thewoodman]

this is only a suggestion, but I have been scratching my head over the same thing for some customers. I finally broke the code. Problem exist especially in the afternoon evening hours hottest part of day. What I found was that the return air grills are mounted in the wall in the hallway. The units are in a closet in the hall. you know mounted up off the floor, plenum going through the ceiling. Underneath is the return air area. Also opened up to the bare 2x4s, you could see the back of the bathtubs from the bathrooms. I am thinking you only want return air from the living area, but in this situation you are pulling return air right down from the attic by way of 2x4 channel. This is by default. So I closed the inside up. Pulling more return from the house and improved the air pressure coming from vents. Boy are those folks happy. They said they actually got cold sleeping last night.

[hiltontech]

I might try the same here at my home because I as many others have a problem cooling my home between 3:00 and 6:00 pm, after that is cools like crazy, I insulated everything I could, I put this unit in when my home was built, even when it was brand new I had the problem, I understand why but explaining to the customers is not that easy to make them understand.