Replacing Furnace - Need help on recommendations

Discussion in 'HVAC Heating & Cooling' started by The old college try, Feb 15, 2013.

  1. The old college try

    The old college try Engineering Technician

    Messages:
    104
    Location:
    MO
    I need help weeding through the process of deciding on a furnace. I have a 23 year old Lennox Whisperheat that I'm thinking about replacing with a high efficiency system since I can get in on some rebate and tax credits. I've had three contractors in for quotes so far and I'm getting differing opinions on what I should do. All three proposed 70,000 btu units to replace my older 100,000 btu outfit. One contractor recommended against variable speed fans because he said that generators wreck them (not that I really use my generator ever), another one recommended an Amana 95% variable, two stage unit and the other recommended a Lennox 96% two stage variable option, but cautioned that the two stage option could decrease comfort on the second floor. My 1600 sf house (with basement) is 85 years old with newer windows throughout, has a lot of attic insulation and has had cellulose blown in the walls in the past. I would by no means consider it to be sealed, but I'm sure it's better than when the furnace was originally put in. Ducts are sized appropriately, or possibly slightly oversized (so I'm told), and oh yeah, I'm in Michigan. Can you help me figure out the best solution for me to increase home comfort and energy efficiency? Thanks.
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,266
    Location:
    New England
    Well, I really like the variable speed fan on my unit. The bigger thing is you really need an analysis done on the house to determine the proper sized unit. A two stage option can be nice. For best comfort, you want long runs. Since the weather isn't below zero every day, having a variable output can help. A variable speed fan prevents the cold surge and noise you get when the thing first comes on since it ramps up, and at the end, ramps down. You may not notice that it's running unless it ever (may not happen often) ramps up to max speed.

    You can get a fair idea of your actual, as used, heat load if you take the amount of gas used and compare that with the degree-days for that month(s). A therm is about 100K BTU (you can get more exact if you wish). See how many therms used, then how many heating degree days there are in the period, and you get the BTU/day, then divide by 24 for the per hour. Depending on what else is run by gas in the house, if you subtract say a summer month's usage from a winter month's, you should eliminate things like a gas dryer, stove, or WH from the equation. It wouldn't be uncommon to have a real heat load in the order of 30-40K BTU. A two stage unit an meet that often on low-fire. Longer runs means better efficiency and less wear and tear on the equipment and comfort is improved.
  3. Failure2Comply

    Failure2Comply New Member

    Messages:
    29
    Location:
    Virginia, USA
    When considering any variable speed "ECM" motor check the replacement costs before deciding, it just might scare you. Even though you can purchase the module separate from the motor they are still vey expensive. Or at least get a 10 year "Parts" warranty if the unit only comes with the standard five year warranty. I would recommend a Trane, American Standard, or a Carrier unit. If you are happy with the longevity and performance of your Lennox that should also be considered. Amana is now a division of Goodman.
  4. The old college try

    The old college try Engineering Technician

    Messages:
    104
    Location:
    MO
    That's the other thing I'm trying to figure out. The Amana guy told me that although Amana was bought by Goodman they are made in different places with different spec's. They look almost identical, though. The Amana unit was proposed with a 10 year parts/labor warranty / lifetime heat exchanger. The Lennox carries a 10 year parts / 5 year labor. I do have to say that the Lennox has been good to me. Had one service call 8 years ago and it was simply a ground issue that was diagnosed and repaired in about 3 minutes. I am concerned after reading about the hassle in getting Lennox parts if something goes wrong. The guy pushing Amana is 10 minutes from my house and they've been in business for years. Very well established with a good reputation. It makes it very difficult to decide.
  5. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    To the best of my knowledge, most, if not all, Amana units come off the same production lines as Goodman models. In fact, it has happened that Goodman shipped Amana-badged units in lieu of a GMS or whatever model, just due to inventory issues.

    As with all brands, there are warranty differences between model series, and to some extent varying with where you buy it....If you purchase from a contractor the warranty may be better than if purchased from a wholesale distributor...but the price will also be different.

    I have stated many times, and am supported by lots of folks on the forum here....that the most important part of an HVAC purchase is the reliability and reputation of the installing contractor.
  6. The old college try

    The old college try Engineering Technician

    Messages:
    104
    Location:
    MO
    Understood. I'm also trying to figure out if I should replace both furnace and a/c or just the furnace at this time. A/C is about 17 years old (10 seer). The Amana guy said that if I just did the furnace he would recommend a new coil be put in. The Lennox guy said that we could just replace the furnace and leave the existing a/c unit as-is if we wanted to. I'm think that the extra $1000 for the higher seer unit in order to qualify for rebates might not be worth it right now. Can anyone shed info on pros/cons of not doing both?
  7. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,266
    Location:
    New England
    A 10 SEER, 17-year old unit could last another 5-years, or could crap out tomorrow. While maybe not cost effective, some of the new ones are good for up to 18 SEER or maybe even more, and the feds have been slowly ratcheting up the minimum for a new one. The refrigerant on the old one, and the lines and coil are not likely compatible with what's required today, and they'd likely have to purge then refill what you have, should you keep it. That extra labor would better be put towards a new unit with a new warranty, and likely MUCH better performance IMHO, especially if you can get some subsidy or rebate. I think there's still some federal tax credits to be had as well.
  8. Failure2Comply

    Failure2Comply New Member

    Messages:
    29
    Location:
    Virginia, USA
    I would recommend replacing all at the same time, more cost effective plus the higher efficiency will save on utility dollars. I am a big fan of efficiency while keeping it simple, less to go wrong. Something in the fifteen SEER rating will give you savings without the extra bells and whistles to break. You mentioned that your ductwork is correct, has it been inspected? Sealing up the joints with mastic and replacing any defective insulation will increase your comfort and stretch your utility dollars. Have them verify that your return is sized properly and I would recommend a .05 static, you CAN NOT have too big of a return, just too small. If you can't get the air in, you can't get it out.
  9. The old college try

    The old college try Engineering Technician

    Messages:
    104
    Location:
    MO
    One step away from the looney bin.

    Thanks for responses. This support group helps me keep my sanity. Now I'm more confused than ever. Had a guy from Carrier out the other day and he was very, very confident in recommending a 2-stage, variable 60,000 btu to provide the best balance of comfort and efficiency. We discussed that a heat load calc would be done if I were to move forward. He agreed but was also very confident with the 60,000 but option. This morning I had a guy from Bryant out. He didn't know what to recommend. He tried to recommend an 80% Payne saying that it's identical to Bryant and Carrier and it's cheaper. I might as well keep my 78% furnace until it dies in that case. He then said that a two stage variable 80,000 btu would be what he might recommend saying that he would never put in a 60,000 btu just in case it was too small. Once again I told him that I wouldn't consider moving forward without a manual J or whatever they do to properly size the thing. Both Carrier and Bryant are reputable installers (not just working on the side out of the back of their van), but Bryant was about $1000 more in price for doing less work than the Carrier install. I'm really leaning toward Carrier. One other option I'm looking at is a 2-stage, Lennox (EL296E) which offers two-stage heat with what they refer to as a "Power Saver Constant Torque" motor that they boast as being 33% more efficient than the others and supposedly has less to go wrong. The guy though this option was better than the variable speed for heating/cooling the second floor. I just want the best balance of comfort and cost. I'm willing to spend a little extra for comfort, otherwise, like I said, I might as well just keep what I have until it dies. Any more thoughts? :confused:

    I wish I were just like the average guy who gets a quote, says "Hey, where do I sign" and is done with it. Too confusing.
  10. Failure2Comply

    Failure2Comply New Member

    Messages:
    29
    Location:
    Virginia, USA
    Carrier bought Bryant, Day and Night, and Payne many, many years ago and became BDP under the Bryant label. All of those companies go back to the early 1900's and were reputable companies on their own, that is why Carrier bought them up. Think of them as Carrier (Cadillac), Bryant (Oldsmobile), Payne (Chevrolet). Have you considered looking at Trane or American Standard? Both are owned by American Standard and are high quality units. I would put Trane, American Standard, or Carrier in my house. Wait for a Manual J load to validate the BTU requirements for YOUR home before selecting a unit. Keep in mind the BTU ratings they are giving you is "Input", not "Output". Since these furnaces are 80% efficient that will be your net output. JMHO
  11. The old college try

    The old college try Engineering Technician

    Messages:
    104
    Location:
    MO
    I thought about Trane/American Standard, but a search on their website didn't list a dealer in the closest city. I think my wife is going to hurt me if I schedule another in-home estimate. I'm really leaning toward the Carrier products since the sales rep was so confident, explained things well, didn't constantly talk about cutting corners to save money and his price was the lowest on furnace and air. Oh yeah, and the Carrier dealer is well respected and has been in business for 47 years. I'm just nervous about heating/cooling issues on the second floor with the variable speed unit, but only 1 out of 6 guys saw that as a concern, so maybe I'm over-thinking this.
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