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  1. #1
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    Jan 2020
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    1948 furnace & 1978 Air Conditioner replacement?

    Thinking about replacing our Furnace and A/C and would love some unbiased opinions and advice.

    Background (or skip to question section if you don't care to read this)

    Our furnace is original to the home (1948) and when we had our A/C serviced this past year, found out it is from 1979. The furnace works just fine to heat the home. The air conditioner struggles to keep up... even in Minnesota and has broken down 5 times in the past 9 years. # of the 5 were simple and obvious electrical fixes I did on my own. The other 2 required a technician. Both technicians told me that the furnace was never meant to have an Air Conditioner installed and that I should consider replacing it all. Neither of them were pushy and recognized that the furnace will probably make it to see another world war before it actually dies.

    Questions:

    Should I? - I am usually an "if it aint broke, don't fix it guy". The furnace works fine. It is likely a maximum of 60% efficient. A/C kinda sucks and is an even bigger energy hog, but it's livable since we are in a colder climate (Minnesota). I am pretty convinced that we are going to replace them, but wouldn't mind being talked out of spending that kind of $$

    Brands - The local companies that come recommended install Trane, Rheem, and Ruud. I understand Rheem and Ruud are basically the same. Is Trane better or worse?

    Venting - Our water heater and furnace are vented together through the chimney. It’s my understanding that if we install a high-efficiency furnace, the ducting for the water heater may need to change in size? Is this correct? Our water heater is 17 years old and could be replaced as well if it's best to do it all at once.

    Manual J - Do I need a manual J calculation? Does the HVAC company that installs them usually do this?


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  2. #2
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
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    You got your money's worth outta that stuff. That furnace is a beauty but I'm sure it is costing you a bundle to run. I lived in Falcon Heights years ago and rented a house with the original 1937 furnace converted to gas. I kept records of daily usage and daily temp. Convinced the landlord the sucker wasn't safe (shoulda seen the cracks in the heat exchanger) and he replaced it with a 68% efficient furnace. Had a huge drop in gas usage. Imagine getting a 96%.

    We sell Rheem and American Standard. Either make a good furnace. AS/Trane have a screwball size return opening on the side of their furnace and for best airflow and filtration, take special installation methods which from what I see aren't too common. Both have good A/C units but AS/Trane are notably quieter and they have compressor pressure switches standard which I like.

    You would need a 3" or 4" chimney liner kit installed for the water heater to vent in.

    Manual J? Good luck. When I was selling I did them but it seems now few do. I was frequently downsizing equipment but didn't like to do so unless I had proof that was right. In 1992 I took a 137,000 BTU 60% out of a lady's house and put in an 80,000 BTU 91% and she raved about the comfort. Ironically just this week my colleague sold the current owner an S9V2 96% 2 stage and new A/C. Just don't let someone look at the BTUs of that monster and put in the same thing - they may not even make them that big anymore. Back then, biggest was bestest!

    BTW, is there a brand plate on the front of that furnace? I can read the Fedders outdoor unit though I recognize them anyway.

  3. #3
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    Jan 2014
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    New England
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    https://www.google.com/url?sa=t&rct=...wxqi0c65CNPb1r

    You can do your own load calculation and or give them the site to compare,....to me it’s the least they can do to get your business, a lot of those older A/C units used 5/16” OD liquid line. If the lineset is easily assessable IMO I would get new lineset that’s matched to your new A/C.

    Ask for AHRI matched equipment, going to 96% furnace you should meet the minimum threshold for any rebates your local gas company or state may have.

    A new furnace will be about 1/3rd the size of that monster.

    Need to register your system of choose as manufacturers warranty decreases significantly if never registered.

    What’s the refrigerant in that thing, R22 or R500...

  4. #4
    Join Date
    Aug 2008
    Location
    Hibbing, MN
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    We just replaced it’s twin sister. It was originally coal, then converted to municipal steam. We put in a Ruud 96% with a heat pump. Our customer had one month last year where their utility bill was over $1,200. That’s electric, Steam, water & sewer. So far, this year less than half of that.

    The hardest part of the job was demolishing and removing the old unit. Especially the blower assembly...It must have weighed 200 lbs!

    If you do replace it, you will see energy savings as well as comfort improvements. Get a good contractor.
    If God didn't want us to eat animals... He wouldn't have made them out of MEAT.

  5. #5
    Join Date
    Sep 2005
    Location
    Atlanta GA area
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    Quote Originally Posted by GenesisRefrig View Post
    We just replaced it’s twin sister. It was originally coal, then converted to municipal steam. We put in a Ruud 96% with a heat pump. Our customer had one month last year where their utility bill was over $1,200. That’s electric, Steam, water & sewer. So far, this year less than half of that.

    The hardest part of the job was demolishing and removing the old unit. Especially the blower assembly...It must have weighed 200 lbs!

    If you do replace it, you will see energy savings as well as comfort improvements. Get a good contractor.
    This is the absolute #1 piece of advise I can give to anyone considering new equipment...
    As installation is more important than the brand.

    Yes, this seems backwards to the way we buy appliances or home repairs (handy folks and remodelers)...
    However HVAC is kinda a unique thing... in that the installation includes sizing and lots of stuff that will affect energy costs as well as the life and reliability of the system, not to mention how comfortable you are in your home.

    The contractor is more important than the brand...
    GA-HVAC-Tech

    Your comfort, Your way, Everyday!

    GA's basic rules of home heating and AC upgrades:
    *Installation is more important than the brand of equipment
    *The duct system keeps the house comfortable; the equipment only heats and cools (and dehumidifies)
    *Cheap is not good, good is not cheap; however expensive is not a guarantee of quality!
    Choose your contractor wisely!

  6. #6
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    Jan 2020
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    Thread Starter
    Quote Originally Posted by BaldLoonie View Post
    BTW, is there a brand plate on the front of that furnace? I can read the Fedders outdoor unit though I recognize them anyway.
    There’s no badge indicating a brand. There’s a marking on it that says “installed by Burnieces economy sheet metal” and what looks like an original sticker that has operation info that says “Certified Furnace Company - a division of stainless and steel co.”

    Quote Originally Posted by Bazooka Joey View Post
    What’s the refrigerant in that thing, R22 or R500...
    R22

    Quote Originally Posted by GenesisRefrig View Post
    We just replaced it’s twin sister. It was originally coal, then converted to municipal steam. We put in a Ruud 96% with a heat pump. Our customer had one month last year where their utility bill was over $1,200. That’s electric, Steam, water & sewer. So far, this year less than half of that.

    If you do replace it, you will see energy savings as well as comfort improvements. Get a good contractor.
    My utility bills haven’t been anywhere near 1,200 in a month, but I am hoping for energy savings and improved comfort.

    The air conditioner will run all day just to try and keep up with even a mildly hot day. I’m taking in the 90°‘s.

    The focus on getting a good contractor and installation does make sense to me.

  7. #7
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
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    Never heard of Certified Furnace Co. but them Fedders were all over the place back home. They met their demise around 1980 when they thought putting a rotary compressor in a heat pump was a good idea

  8. #8
    Join Date
    Jan 2020
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    Thread Starter
    I’ve had one estimate for new equipment and am getting 2 more this week. I have a couple questions for you experts on here...

    1. Modulating vs 2 stage is more about comfort than efficiency? Correct? It does appeal to us. If the price difference is under a grand, would you advise getting a modulating furnace?

    2. Rheem and Ruud equipment are basically the same, correct?

    3. We are interested in a humidifier as we live in Minneapolis and it gets dry. Our house is sealed well. I have guitars that like to live at 45% and my wife is a hair stylist and washing peoples hair every day dries her hands out quite a bit. Is a whole home unit good? Or just use room humidifies? The company that came out recommended the Aprilaire 600

    4. What are your thoughts on Air Cleaners? We’ve been using the absolute cheapest fiberglass spun filters to not restrict air flow in the current system, so I imagine any other filter that is compatible with new equipment will be an upgrade in air quality. Is a air cleaner a good idea? Do they help the unit last longer? Do they restrict airflow too much? In general are they a good idea or a waste of money?

    Thanks!!!

  9. #9
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    Aug 2002
    Location
    Southold, NY
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    Has anyone actually done a Manual "J" yet or are replacing size for size.

  10. #10
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    Thread Starter
    Quote Originally Posted by pecmsg View Post
    Has anyone actually done a Manual "J" yet or are replacing size for size.
    The first company did not do a load calculation.

    They recommended 60,000 BTU Furnace and 2 ton Air Conditioner.

    Some info on my home:

    Location - Minneapols, Minnesota
    Year - 1948 with attic and basement full remodel in 2013 and 2016.
    Size - 2400 total Sq Ft / 2160 finished Sq Ft.
    Style - 1.5 story with conditioned attic space.
    Blower door test results - 1,534 CFM50 @ 2400 Sq. Ft.
    Insulation R-Values:
    - Basement Floor - None below or above the concrete - Carpet probably provides a tiny bit.
    - Basement Walls - R-22
    - Rim joist cavities - R-30
    - Main level Walls - R-5 - 7.5 (old insulation... this R value was determined by a home energy audit who cut a few holes in different spots to record how much insulation is in the wall.
    - Attic (partially conditioned):
    • Floor beind knee walls - R-50
    • Knee walls - R-20
    • Slant section - R-20
    • Ceiling section - R-50

  11. #11
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    Aug 2002
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    Southold, NY
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    You MUST get a Manual "J" Performed also with those ducts a Manual "D".

    Was that unit Belt Driven?

  12. #12
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    Jan 2020
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    Thread Starter
    Quote Originally Posted by pecmsg View Post
    You MUST get a Manual "J" Performed also with those ducts a Manual "D".

    Was that unit Belt Driven?
    Yes - It's belt driven. I plan to get a Load Calculation.

  13. #13
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    May 2000
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    Indianapolis, IN, USA
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    1. Modulating furnaces are amazing. They almost perfectly follow the needs of the house with the proper control. Should get the same mfr's communicating control for best operation.

    2. Identical

    3. 600 is just fine. I'd go the manual model. Then have the furnace control handle it.

    4. Get something, Honeywell F100, Trion Air Bear, Aprilaire media air cleaner. So much better filtration than a 1" fiberglass and much less restrictive than a 1" pleated.

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