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  1. #1

    New AC, Need help

    Looking for some opinions and suggestions on the new AC unit on a rushed decision. After finding this forum I realized all the mistakes I made in buying a new AC system as I'm sure you all will too. The reason it was rushed is because we were leaving on vacation the day it stopped blowing cold air called a place out to find the compressor has failed.

    I live in SE Michigan just outside of Detroit in a 1150sq ft 1960's brick ranch home. The AC system that was in the house when we bought 4 yrs ago was a Lennox Elite HS29-024-1P. Pretty sure it was a 13 seer 2 ton system. The furnace we have is a Lennox 80MGF series, not sure on all the details on the furnace.

    Like said above came home from work Monday, noticed ac was blowing room temp air, turned it off, looked up online what to check. Realized compressor wasnt running but the fan was. Visually looked at capacitors and looked for loose wires, looked fine. Tuesday morning we called my wife cousins family friends small company (did their whole house/figured trustworthy if they had good service) They were in the area on a job and waited around til 4 for them to be done. I stood outside and watched, he checked capacitors and hooked up new one, checking voltage and explained what he did but got nothing from the compressor. He concluded the compressor went out. Sounded right to me but now wishing I got a second opinion. So he said to replace the compressor with
    other parts that should be changed would be cheaper but not the best option. His other recommendation if we plan on living here for a while was all new system, his recommendation was the Lenox 13 acx. Seemed pretty comparable, 2 ton 13 seer. Against what I was thinking about making a rushed decision, we did and set it up for this past Monday. We knew the temps were going to be high coming home from vacation, we have a 20 month old and price seemed to be comparable to other people i know in similar size houses.

    3 hr install, was blowing about a 15-20 degrees cooler than outside air. Seems like it was going to be fine. A few things now worry me on that fast decision. Yesterday it was 89 out and 30% humid. Ac was turned on around 11am, we set it usually at 77, it read 80 in the house all day until 9:30 at night it dropped to 79. At night I usually turn it up to 78, so I do that around 10pm, at midnight it reached 78 and shut off. Does not seem normal to me. Our old on did also struggle on hot days but I do think it would have preformed better on an 89 degree day. I do get a small brick ranch has a lot of heat on the outside, our attic is well insulated, did 10 inches of blow-in 2 years ago, newer windows, keep blinds shut. Most of the neighbors units run constantly all day too so maybe its just normal for the year house, size and many other factors. Just seems strange the ac can only cool 9 degrees cooler than outside temps.

    So i guess my questions are, did I buy an undersized unit? I read on here that an AC company should do heat load tests or other calculations to determine the right size, they didn't do that. I assumed they matched to the old unit which for all i know wasn't adequate.

    I plan on calling them about this and asking what they think the problem is or how they determined this was the right sized unit. I assuming I'm stuck with this now? or if they wrongly sized it couldn't I tell them they need to replace it with the correct size?

    Just don't know my options as this is my first major appliance dealings and Im pretty sure I did it completely wrong. I'm almost thinking or calling another company just to come out and see what they say too. Lesson learned for everything in the future though but I payed a good amount of money, I should have a properly working ac unit. Last, how much does a furnace play a part in cooling, could our furnace prevent proper cooling?

    Any suggestion, opinions and help will be appreciated
    Last edited by belusart; 08-08-2012 at 12:07 PM.

  2. #2
    Join Date
    Jul 2007
    Location
    Delaware
    Posts
    3,824
    He installed both the outdoor & indoor A-Coil for that price (which will down soon, no pricing on this site) ?
    Always here

  3. #3
    Join Date
    May 2008
    Location
    Missouri
    Posts
    3,494
    First off, what are the actual model numbers of the equipment you had installed? Are you turning off the AC and waiting until house is hot before turning it back on (I noticed you "turned it on at 11am)? If you are turning AC off, opening house up, and then closing home and turning it on during hottest part of day, then you can't really expect comfort. In hot weather it's always best to leave house closed up, with AC turned on all the time. Otherwise the AC has to play "catch up" during the hot part of the day and your comfort (and cooling bill) will suffer.

  4. #4
    Energystar- Sorry about the price thing, i edited it out. Yes he did install everything for that quoted cost. It was for Lennox 13acx-024-230-12, condensing unit, coil, cineset, sheetmetal, plumbing, misc and labor. So it was inside and out. Thats right from the quote page and he took me around and showed me everything he did.

    wahoo, yes the AC was turned on a bit late and I know it does play catch up turning it on late. Today is another hot day, mid 80's I think, and the air is on. My wife is at home with it on so I'm going to call soon to check. But I set it to 77 and was 76 in the house in the morning so it will be a good test today when it heats up and the ac kicks on if it can keep up. The house has been closed up since yesterday.

    But even with our old ac unit during multiple hot days the AC would rarely reach the set 77 degree temp during the day, at times it would but wouldnt ever cycle, just constantly run. Always seems like catch up. I always wondered if the old ac was undersized or just circumstantial to the old brick houses.

  5. #5
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    4,973
    Detroit MI area 2.5% summer design is 88F dry bulb 72F WB or 46% RH.
    A 2-Ton A/C should be plenty big if not oversized considering your climate & fairly high humidity conditions. (Unit is not performing well.)

    Well, if U want to do some simple temperature checks verses what the nominal performance data of that tonnage & SEER Rating unit's data should be, then check the following temperatures & humidity.

    After taking the data you will need to call an Energy Efficiency HVAC Technician & provide them some documented data clues as to where the problems seem to be. Tell the contractor/Tech about this forum.

    All U need is a good thermometer (digital reading in tenths preferable) & and indoor Humidity Gauge

    1) Helpful; Tonnage & SEER of Unit &/or outdoor condenser model number: ____________ Matching indoor coil # ______

    2) TXV or, orifice metering device? _______. Only if U know…

    3) Outdoor condenser’s discharge-air-temperature ______-F
    Subtract Outdoor air temperature: _______
    Outdoor Condenser Air-Temp-Split _______

    4) Need the ‘Indoor’ percent of relative humidity - in the middle of the rooms or, at Return-Air inlet grilles ___
    5) Indoor Return-Air Temperature ______
    Subtract Indoor Supply-Air Temperature ______ -F
    Indoor temperature-split _______-F

    If U can find a turn in the small liquid line insulate the temperature-probe; get its temperature for the subcooling analysis:
    Small liquid line temperature ____F

    Need the above information for troubleshooting & performance analysis.

    Example below:
    A Goodman 2-Ton 13-SEER condenser, @800-cfm indoor airflow; 80-F indoor dry bulb & 50% relative humidity; Indoor temp-split 18 to 19-F.
    @ 85-F outdoors; 103.9-F - 85-F outdoors or around an 18.9-F temp-rise-split;
    @Indoor 75-F, 63-wet bulb around 50% RH - condenser temp-split is only 14.9F.

  6. #6
    thanks udarrell, I will get a thermostat and humidity gauge and fill this out. Talking to some neighbors today all have the same issues and seems common in these houses. I also found out that these 60's houses have absolutely no insulation in the walls. I assume thats a big factor. 80% of our basement ceiling is dry-walled so can't really see if the ducts are leaky, could be why the air blowing out doesn't feel real strong. These are things I always wondered about since buying the house.

    So would an Energy Efficient Tech be the person who could find out if our house is too drafty or if ducts are leaking air? I guess there so many thing to consider it might be best to get an evaluation of some sorts.

  7. #7
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    4,973
    Quote Originally Posted by belusart View Post
    thanks udarrell, I will get a thermostat and humidity gauge and fill this out. Talking to some neighbors today all have the same issues and seems common in these houses. I also found out that these 60's houses have absolutely no insulation in the walls. I assume thats a big factor. 80% of our basement ceiling is dry-walled so can't really see if the ducts are leaky, could be why the air blowing out doesn't feel real strong. These are things I always wondered about since buying the house.

    So would an Energy Efficient Tech be the person who could find out if our house is too drafty or if ducts are leaking air? I guess there so many thing to consider it might be best to get an evaluation of some sorts.
    Some utilities do Home Energy Efficiency Audits, check all the energy companies that serve your heating & A/C systems; especially the electric company; they do it to keep peak-loads down to save on costly power plant expansions.

    The air flow CFM volume delivery to the rooms needs to be checked by someone who knows how to do it right.

    After the home & duct system upgrades a room by room heat-gain & heat-loss needs to be performed to figure what the Btuh & then figure what the CFM to each room should be.

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