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  1. #1
    Join Date
    Sep 2010
    Posts
    32

    HE AC unit costing me more per month... Why?

    I had an 11 year old Goodwin that died last year. I think it was a 4(or5) ton. When the new installers came they said that I needed a 5 ton. I had some come and tell me that I need a 4 and others that said a 5. They all did the measurements around the house, added the window thickness and that the temp that I like to keep the house at (I need it cold due to a head injury). The company I choose swore that I had to go with the 5 ton variable unit. So I did.

    My house is 1832 sq ft. I live in Arizona so it gets very hot. With my old unit I used to keep the house set at 74 during the day and 68 at night. Since installing the new unit I've had to keep the house at 72 during the day and I still keep it at 68 at night. I asked the company why I had to lower the temp with this new system and they just said that it happens but I'll be saving money anyway with this new HE system.

    It's almost a year later and when I compared my bills from 2010 & 2011 on the APS website it shows that I'm paying more since using this new system.

    I thought I was supposed to save money when switching to a HE unit.

    Why would this be? Could the unit be too big for my house? Should I get the 4 ton?

    Thank you for your help.

  2. #2
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,787
    Well, I can't see the unit from here, but your post raises a lot of questions in my mind.

    If you put a 5 ton system in place of a 4 ton system without upgrading the ductwork, you might have some trouble.

    Was the system properly tested at startup? Newer systems are pretty critical in their operation.

    Do you do regular maintenance on the unit? Have it professionally serviced regularly?

    The first thing I'd do is have it evaluated by a qualified professional. You can call the installer or contac another local company. There is a link to a map in my signature lines and you may actually be able to find a pro who frequents this site.

  3. #3
    Join Date
    Oct 2007
    Location
    Austin Texas
    Posts
    1,804
    Also check and see if your electric rates per KWH have not gone up.
    Nemo me impune lacessit.

    How much blood do I have to bathe in to get clean?

    Don't look down on anyone unless you're helping them up.

  4. #4
    Join Date
    Aug 2011
    Posts
    568

    Confused

    Quote Originally Posted by John Culpepper View Post
    Also check and see if your electric rates per KWH have not gone up.
    mine went up this year, and depending on out door teps, unit could've been running longer

  5. #5
    Join Date
    Sep 2010
    Posts
    32
    All the duct work was redone with the new unit. I actually think the old unit was also a 5 but some of the contractors that came out said it should be a 4 ton.

    I scheduled an appt for the company to come out and take a look. I've had a few problems since they installed it. Some rooms weren't getting air and they came out to change the vents and ducts to accommodate this. Then the return vent makes this annoying whistle sound. At first the company said it's because the filter needs to be changed but it start doing it again within a few days after a new filter is put in. I change them once a month.

    Another time a guy came out and said that there wasn't enough freon in the line. Due to the large size of this new unit they had to place it further away from where it used to sit but it appears as though they didn't calculate the freon to make up for this distance. Now it should be fine.

  6. #6
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,339
    Quote Originally Posted by jpsmith1cm View Post
    If you put a 5 ton system in place of a 4 ton system without upgrading the ductwork, you might have some trouble.

    Exactly. Most of the time ductwork is insufficient for the size you have let alone going 25% bigger.

    Did you compare cooling degree days for same periods?

  7. #7
    Join Date
    Jul 2007
    Location
    Chicagoland
    Posts
    479
    Just a few thoughts on your situation, obviously a full evaluation by a properly trained tech will be necessary.

    1. If you had to set the temp 2 degrees lower to feel comfortable, the new system may not be dehumidifying as well as the old one. Airflow and system capacity effect moisture removal.

    2. Variable speed blowers operating at a set airflow rate (CFM) can consume excessive power when trying to push/pull that air through under sized ducts. The whistle you hear could be related to high static pressure.

    3. It's been HOT! almost everywhere, and humid too. Check several years data and compare apples to apples not just the dollar amount.

    Hopefully these points will help to steer you in the right direction.

  8. #8
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,367
    Only 1 return grille? How big is it.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  9. #9
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    5,012

    Lightbulb

    My house is 1832 sq ft. I live in Arizona so it gets very hot. With my old unit I used to keep the house set at 74 during the day and 68 at night.

    Since installing the new unit I've had to keep the house at 72 during the day and I still keep it at 68 at night.

    I asked the company why I had to lower the temp with this new system and they just said that it happens but I'll be saving money anyway with this new HE system.
    Your home is the most important part of the HVAC system's performance curve; followed by an efficient duct & airflow system.

    Central air equipment represents a major investment with monthly energy costs which needs be dealt with in the most cost-effectively ways possible.

    When contractor's are talking about 4 & 5-Ton systems in an 1832-sf home, we should always begin with a Home Energy Efficiency Audit to determine what cost effective options need to be applied before doing a Manual J, D & T.

    AZ has a dry but hot climate, there are effective ways to lower heat conduction & solar radiation.

    I'm guessing that with effective retrofitting at least a 3.5-Ton could achieve your comfort zone with efficient & quiet airflow to all rooms.

    Only a thorough & complete analysis, - would enable your goal of substantially lowering your utility bills while achieving the comfort levels you demand.

  10. #10
    Join Date
    Nov 2009
    Location
    West Monroe, LA
    Posts
    287
    Quote Originally Posted by AccurateHT View Post
    Just a few thoughts on your situation, obviously a full evaluation by a properly trained tech will be necessary.

    1. If you had to set the temp 2 degrees lower to feel comfortable, the new system may not be dehumidifying as well as the old one. Airflow and system capacity effect moisture removal.

    2. Variable speed blowers operating at a set airflow rate (CFM) can consume excessive power when trying to push/pull that air through under sized ducts. The whistle you hear could be related to high static pressure.

    3. It's been HOT! almost everywhere, and humid too. Check several years data and compare apples to apples not just the dollar amount.

    Hopefully these points will help to steer you in the right direction.
    I agree with all but number 1 makes the most since! So let's say you had a 4 ton then they put a 5 ton in now you have to run the t-stat 2 degress lower to feel comfortable. What that tells me that the 4 ton system was removing more humidity and ran longer cycles. Know you have a 5 ton system that is running less until you lower the t-stat down 2 degrees to get the same comfort as your system did at 74. Does this make since?

    Even though it is a brand new system with higher seer rating you are still having to run it lower to stay comfortable in turn causing you to use more electrical. Know I well say that it has been a hot summer for all but it was last year as well just not as bad. Also there could be other factors that needed to be addressed such as return, duct size, ref. Charge, etc....

  11. #11
    Join Date
    Sep 2010
    Posts
    32
    (BTW the 11 year old Goodman was a 4 ton).

    The AC guys came back out and did another load calc. They keep on insisting that there's nothing wrong with the system and that the load calcs are correct. But it doesn't make any sense because all my electric bills are showing higher KW since this new 5 ton variable speed Bryant unit was put in.

    In addition, I have another house less than a mile away that's 2800 sq ft, 2 story with 2 AC units (1 upstairs and 1 down). We keep this house at the same temps of 74 during the day and 68 at night. We decided to change out the first floor unit to the same 5 ton variable speed Bryant unit and since changing to the higher SEER on this house we're saving a great deal of money and using lower KW per month.

    Here is the last letter that the AC company wrote to us (keep in mind that they were fully aware that I kept my temps at 74 during the day and 68 at night).

    "There is not a problem per say, the temp you want the home is the issue there is nothing wrong with the system and it is running as good as it can… 5 ton is the biggest system made so we are stuck because of that temp there are no options or upsizing or getting a bigger system
    You never mentioned to me the 68 degree temp till now it was 74 degrees, and if you keep the house at 68 you will not save any money, I know you have a higher seer system and you think it should save you money but not at that temp!, new systems are built on efficiency, not horse power, so the temp is important.. at this point with that temp being 68 there is truly nothing we can do to help the issue, if the home is going to be at 68 degrees for almost half the day, there is nothing that we can do to help the issue at hand, I think maybe we should have the register of contractors get involved"


    Please share your thoughts and comments. The 1 year warranty is up in a couple of weeks and I don't want to be stuck with something that isn't energy efficient.

  12. #12
    Join Date
    May 2008
    Location
    Missouri
    Posts
    3,583
    You've never addressed the question of utility cost as to whether or not the actual price has changed. But as they mentioned, keeping your home at 68 degrees is VERY difficult for any AC unit. We never recommend anyone go below 70 degrees, without further low temp controls added to the indoor unit to keep it from freezing up or trying to nearly all the time. The whisling worries me though.....does not seem right. You aren't using the 1" pleated air filters are you?

  13. #13
    Join Date
    Sep 2010
    Posts
    32
    I do believe that the prices have gone up somewhat but that still wouldn't explain why the KW have gone up per month.

    I've been keeping the night temps at 68 for years with the older unit... why would this one not work as well if not better? I have an head injury and need to keep temps low at night.

    As for the whistling, I do not use the pleated filters. It seems to come and go. I don't know why.

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