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  1. #1

    Replacing central air and gas furnace

    Our furnace/ac is 17 years old. Still works but we are preparing to remodel and thought it would make sense to replace the unit. It is also an older rheem that has the recall on the vent pipe and it is past time to replace. I have had 3 hvac contractors out to look at it for a quote. In the meantime, I discovered the main duct trunks are the fiberglass duct board (17 years old) they is a fair amount of debris in the ductwork near the intake. Also the fiberglass seems very brittle and easily flakes off. I don't know about you, but I do not like the idea of sucking all the air I breath through fiberglass surfaces. We live and work at home so we are here 24-7. I feel strongly now the main trunk ducts need replacing which will involve tearing out part of the ceiling in the basement. I assume the rest of the ductwork is the flexible plastic coated stuff. All this to say I am very interested in the Mitsubishi ductless system as a replacement. This would bypass all the old ductwork. I would also zone the system which would help to seperate the studio system from the rest of the house. I don't have quotes on the minisplit yet but it looks to be 30 -70% more the the conventional replcement with the ductwork. The replacement quotes are for a dual fuel system. Anybody know how the lifespan compares betweeen the 2 systems. What do folks think about the minisplit in this application? Any other ideas about the ductboard? Finally, the three quotes we for: American Standard, Amana and Lenox. Any thoughts on which would be the best choice? Many thanks, Jim
    Last edited by bellabella; 09-19-2009 at 11:59 AM. Reason: Removed prices

  2. #2
    Join Date
    Jan 2004
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    Lancaster PA
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    Removed your prices, no prices allowed in post.
    Please read site rules, Thank you.
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  3. #3
    got it.

  4. #4
    Join Date
    Aug 2009
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    21
    mini split are great system but not cost efficient in residential.. initial cost is too high (almost double) and they are not great as primary source of heat.. i was doing almost sane job at my home and had quote from all systems but i guess looking it from all angle i guess gas furnace with higher efficieny will be better,,, ductless is great for cooling home.. but u really need to have great installer,,, there are not a lot out there...

  5. #5
    Join Date
    Aug 2009
    Location
    Long Beach CA
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    182
    The deal with a mini-split is that you have to have a unit hanging on the wall. (there are exceptions, there is an air handler box available for some systems) They work great, but I would only use one where it solved a problem (like how am I going to get A/C into there?) rather than as a whole house solution. You would also be limited to heat pump warm air. This may or may not be adequate depending on geography. (you do not state where you live) If you feel that you would like more control of where the air goes, a conventional system can be zoned.

  6. #6
    I live in Western North Carolina. What are the alternative to the fiberglass duct board for the trunk ducts?

  7. #7
    Join Date
    Nov 2008
    Location
    Chapel Hill, NC
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    1,070
    Metal trunk ducts with metal or flex duct branch lines. Select a dealer/installer that has, or has access to, metal ductwork fabrication resorces - they should be able to do a cost-effective job of replacing the ductwork. It's a little more complex than an all flex duct install but much better quality. Have the metal trunk lines externally insulated.

  8. #8
    Join Date
    Nov 2008
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    Quote Originally Posted by bellabella View Post
    Our furnace/ac is 17 years old. Still works but we are preparing to remodel and thought it would make sense to replace the unit.
    Your unit has reached 45% of the average U.S. resi. HVAC lifespan. I don't have more detailed mortality tables for the subcategories of HVAC equip. but these forum members probably do, from their business records.

    There is also a purely financial method for deciding equip. replacement strategy but it's hard to follow without being able to post prices.


    If you do a Dot Plot of your bids

    ...a....bcd..e....f
    0.....|.....|.....|.....
    relative price..$

    do the bids cluster together?

    In the example, a & f are outliers and the true cost for doing the job in your zipcode today is probably c or d.

    There is also a "credibility factor" [a weighted average] which can be blended in. Contractors who don't do a Manual J calc. or Manual D calc. get less credibility.

  9. #9
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    The middle ones of that plot, could be the worst companies to use.

    And that plot does not represent the true cost.
    The middle ones could be the ones that didn't look the job over very well. And are just using a price per sq ft method.
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  10. #10
    Join Date
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    The middle ones of that plot, could be the worst companies to use.

    And that plot does not represent the true cost.
    The middle ones could be the ones that didn't look the job over very well. And are just using a price per sq ft method.
    Contractor locator map

    How-to-apply-for-Professional

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

  11. #11
    Join Date
    Nov 2008
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    Quote Originally Posted by beenthere View Post
    The middle ones of that plot, could be the worst companies to use.
    That is unlikely

    And that plot does not represent the true cost.
    To some degree of likelihood, it does.
    http://en.wikipedia.org/wiki/Confidence_interval

    The middle ones could be the ones that didn't look the job over very well. And are just using a price per sq ft method.
    If you get enough bids the greed and incompetence will cancel out.

    Nice to see you again, Mr. T.

    These kind of techniques are what got me illegally forced out of my government job.

    If the bad guys are afraid of it, it probably works.

    You should check how many republicans die in plane crashes. It seems to be the statistically significant method of choice for getting rid of political enemies.

    http://en.wikipedia.org/wiki/Statistical_significance

  12. #12
    Join Date
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    Throwing out bogus statistics doesn't help people.
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  13. #13
    Join Date
    Nov 2008
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    Quote Originally Posted by beenthere View Post
    Throwing out bogus statistics doesn't help people.
    Knowing credible information is a dominant strategy
    http://www.google.com/search?client=...UTF-8&oe=UTF-8
    because you can always disregard it.

    It's like carrying a gun. You don't have to use it but it come in handy if you need it.

    I could swear my posts are better when I've had some rum. . .

    Bogus?
    http://www.google.com/search?client=...UTF-8&oe=UTF-8
    Verily, milord, I think not!

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