Furnace options
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Thread: Furnace options

  1. #1
    Join Date
    Jul 2008
    Location
    Columbus, OH
    Posts
    10

    Furnace options

    I'm looking at a gas furnace (20 year) and AC (15 year) replacement and have some questions primarily about the furnace options I have before me:

    80% vs >90% efficiency; is the higher efficiency worth it? I'm in Columbus, OH and my yearly gas bill is ~$1200 and I estimate ~$800 is for heating. Is it simply looking at the % differential and finding an acceptable payback time period?

    multiple speed vs variable speed; is variable speed much better than 4-speed?

    any other features of a gas furnace that I should consider?

    I have quotes on Trane, Lennox and Rheem systems. One definitely recommended the 80% afue, another provided the higher efficiency info when asked and the third's starting point was the high efficiency.

    From what I've gathered here, most would say that these manufacturer's all put out good products and that it is the installation that makes for a good working system. Other than that, any particular recommendations for a Trane, Lennox or Rheem?

  2. #2
    Join Date
    Nov 2005
    Posts
    11
    I would install a complete Carrier infinity system if replacing the whole system
    You can get a good rebate back from carrier and get a good payback if living there for a while.

    You can go to a high efficiency 90% plus furnace but have to pay some extra labor to run new pvc flue out of the house or if you choose to go with 80% and use existing flue you can get two stage heat with variable speed. Two stage is less wear and tear on the heat exchanger and a more comfortable heat. Variable speed is the smartest way to go for dehumidification features in the summer. Also a way quieter motor some customers can't even hear it run and have to feel their vents to see if its running. You get good benefit for heating as well a more comfortable heat and even temps around the house. What ever you go with make sure you good a good upgrade on your filtration the smartest thing you can ever do
    good luck

  3. #3
    Join Date
    Mar 2008
    Location
    Central Maryland
    Posts
    246
    Quote Originally Posted by cafco View Post
    80% vs >90% efficiency; is the higher efficiency worth it? I'm in Columbus, OH and my yearly gas bill is ~$1200 and I estimate ~$800 is for heating. Is it simply looking at the % differential and finding an acceptable payback time period?
    The answer depends on the price differential between 80+ and 90+. It sounds like you need to know that differential from each of your quoting companies.

    For me, the difference small enough as to make it a no-brainer. Your milage may very.

    Quote Originally Posted by cafco View Post
    multiple speed vs variable speed; is variable speed much better than 4-speed?
    Variable speed uses less electricity, and usually runs constantly (pull about 60-75 watts) to keep air moving in your house and even out hot and cold spots. I recently upgraded to a VS (Variable Speed) Rheem furnace and it does help. It won't eliminate the upstairs/downstairs temp differential, but what it did do is help the "one room" that was always cold in Winter and hot in Summer.

    Quote Originally Posted by cafco View Post
    any other features of a gas furnace that I should consider?
    Variable Speed furnaces usually have a mode where the accelerate dehumidification in A/C mode by slowing the fan. This mode can often be changed from algorithmic (guessing) to actual by simply adding a humidistat. This should be a fairly affordable option.

    Quote Originally Posted by cafco View Post
    I have quotes on Trane, Lennox and Rheem systems. One definitely recommended the 80% afue, another provided the higher efficiency info when asked and the third's starting point was the high efficiency.

    From what I've gathered here, most would say that these manufacturer's all put out good products and that it is the installation that makes for a good working system. Other than that, any particular recommendations for a Trane, Lennox or Rheem?
    You would probably be happy with any, I have the Rheem modulating furnace, which is supposed to be the tops in its class. I am happy with it.

    -HF

  4. #4
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
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    33,829
    Dual fuel!

  5. #5
    Join Date
    Jul 2008
    Location
    Columbus, OH
    Posts
    10

    Serious response?

    Quote Originally Posted by BaldLoonie View Post
    Dual fuel!
    Is this a serious suggestion?

  6. #6
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,829
    You bet! You're just a few hours from us, same climate, probably similar electric rates. Dual fuel is a great way to save on the old heat bill. In our area, 80% furnace and 13 SEER pump is a cheaper heating bill and usually lower installed price than 90+ furnace and 13 SEER A/C. Spend the bucks for 90+ furnace and pump and you'll really save. Next door I went from 8 SEER A/C to 10 SEER pump and 65% furnace to 93% furnace. First December they had it was colder than the winter before and their gas bill was UNDER HALF the December before and electric bill hardly went up. And no complaints about comfort!

  7. #7
    Join Date
    Jul 2008
    Location
    Columbus, OH
    Posts
    10

    Variable speed

    Quote Originally Posted by hangfirew8 View Post
    Variable speed uses less electricity, and usually runs constantly (pull about 60-75 watts) to keep air moving in your house and even out hot and cold spots. I recently upgraded to a VS (Variable Speed) Rheem furnace and it does help. It won't eliminate the upstairs/downstairs temp differential, but what it did do is help the "one room" that was always cold in Winter and hot in Summer.

    Variable Speed furnaces usually have a mode where the accelerate dehumidification in A/C mode by slowing the fan. This mode can often be changed from algorithmic (guessing) to actual by simply adding a humidistat. This should be a fairly affordable option.
    Thanks for all the comments.

    Is the VS aspect of moving air significant to feel cooler? We currently have a fan going in our "one room" (hot/cold summer/winter) even with the AC on to move the air.

  8. #8
    Join Date
    Jul 2008
    Location
    Columbus, OH
    Posts
    10

    Thanks

    Quote Originally Posted by homeless View Post
    I would install a complete Carrier infinity system if replacing the whole system
    You can get a good rebate back from carrier and get a good payback if living there for a while.

    You can go to a high efficiency 90% plus furnace but have to pay some extra labor to run new pvc flue out of the house or if you choose to go with 80% and use existing flue you can get two stage heat with variable speed. Two stage is less wear and tear on the heat exchanger and a more comfortable heat. Variable speed is the smartest way to go for dehumidification features in the summer. Also a way quieter motor some customers can't even hear it run and have to feel their vents to see if its running. You get good benefit for heating as well a more comfortable heat and even temps around the house. What ever you go with make sure you good a good upgrade on your filtration the smartest thing you can ever do
    good luck
    Thanks for the suggestions.

  9. #9
    Join Date
    Jul 2008
    Location
    Columbus, OH
    Posts
    10

    Dual Fuel payback

    Quote Originally Posted by BaldLoonie View Post
    You bet! You're just a few hours from us, same climate, probably similar electric rates. Dual fuel is a great way to save on the old heat bill. In our area, 80% furnace and 13 SEER pump is a cheaper heating bill and usually lower installed price than 90+ furnace and 13 SEER A/C. Spend the bucks for 90+ furnace and pump and you'll really save. Next door I went from 8 SEER A/C to 10 SEER pump and 65% furnace to 93% furnace. First December they had it was colder than the winter before and their gas bill was UNDER HALF the December before and electric bill hardly went up. And no complaints about comfort!
    Thanks for the thought about the HP, I hadn't considered it. However, it seems like the payback will be significantly long especially with the high efficiency furnace. I was already thinking 80 to 93% might be in the 7-10 years. Add the additional expense of the HP and it probably extends that probably goes to 12-15 years since it will be used even less. One would have to see significant savings with the HP. I don't know that my electric rates ($0.11/kwh) will give me that much of an advantage.

  10. #10
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,597
    Whats your gas rate?

    Keep in mind, that all utilities/ heating fuels are going to continue to rise.

    Oil heat is plentiful in my area. But because of its rising price. MOre people are swithing to heat pumps, or gas heat.
    As the demand for gas rises, so will its price across the country.
    5 years from now, your nat gas price could double.

    Dual fuel with a 90% will keep your heating bill as low as possible for years to come.

    You don't have to get a VS blower. But they are nice to have.
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  11. #11
    Join Date
    Mar 2008
    Location
    Central Maryland
    Posts
    246
    Quote Originally Posted by cafco View Post
    Thanks for the thought about the HP, I hadn't considered it. However, it seems like the payback will be significantly long especially with the high efficiency furnace. I was already thinking 80 to 93% might be in the 7-10 years. Add the additional expense of the HP and it probably extends that probably goes to 12-15 years since it will be used even less. One would have to see significant savings with the HP. I don't know that my electric rates ($0.11/kwh) will give me that much of an advantage.
    I know, it is hard to cost justify adding a bunch more equipment to your setup. Fortunately for me, I was able to do it once piece at a time.

    On energy use and dual fuel, if one fuel goes up, you can change the set point to use more of the other. If electricity is cheap, set the changeover point low, if your get a good deal on a propane fill, set it to a higher temp.

    Still, it will take a long while to pay off dual fuel in energy savings, if ever. The advantages, from my viewpoint, are:

    1. Real comfort from gas heat when the weather gets really, really cold.
    2. Runs off of a reasonably sized generator (whereas a heat pump with electric backup needs a very big generator).

    Part 2 may not matter to you.

    -HF

  12. #12
    Join Date
    Jul 2008
    Posts
    17
    I vote for trane, but all three would do the job well. Dual fuel is a great way to go if you want to save on your energy bills. I have a trane 95% efficient variable speed furnace in my house and i love it. What ever way you go i would get a variable speed furnace.

  13. #13
    Join Date
    Jul 2008
    Posts
    551
    IMO, as it has already been stated if you go with a conventional furnace/AC setup, definitely get a furnace that is 95% or 96% efficient.

    My personal preference is to go with an 80%+ furnace and a heat pump. The two systems should be around the same price.

    As for stages and variable speed, that is up to you. You can get a pretty darn efficient SEER13 system for less than a 2-stage SEER 16+, but you "might" be able to get a more comfortable house with a SEER 16 & variable speed setup. I don't know that you'd ever see a payback going from the SEER 13 to the SEER 16.

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