Replacing furnace. Wondering what bells and whistles to get.
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  1. #1

    Hmm

    Hey guys,

    Cool forum. I did a search but couldn't find a real good answer to my questions. Here's my story. About 8 years ago I bought an old (1918) farmhouse (2100 sf 2-story) in southern Indiana. It had a 1960 vintage furnace in it that I replaced after the 1st winter with an 80+ 125,000 unit. I did not swap the a-coil out. The previous owner had replaced it and the compressor unit right before we bought the house. I think it's 4 tons.

    Since then, I've done some insulating in the attic, and replaced some of the windows. The furnace has never had any problem keeping up, even when we hit 20 below last year (extremely rare in this area).

    I have 2 issues with my system:

    1. Energy has gotten more expensive and I'm kicking myself for not buying a higher quality system.

    2. This thing is LOUD. I mean it's FRICKING LOUD!!! When the blower kicks on, I have to turn up the volume on the TV. I have to talk louder. It's really annoying.

    So...seems like I would be an ideal candiate for a 92+ furnace with a 2-speed or variable speed blower. My questions, though, are these:

    1. Looks like the variable speed blower costs about $400 more. If I understand what I've read, it actually only operates on 2-speeds anyway...it just senses the "proper" speed to run at for high or low operation. Is that worth $400?

    2. The variable speed furnace I'm looking at (a Heil model) also includes a 2-speed draft fan vs the standard single speed. Does that make it worth the extra money especially considering I want something quiet. For reference I can clearly hear my draft motor on my LOUD 80+ fire up now.

    3. Zoning a possibility? The bedrooms in my house are upstairs, the living area is downstairs (as is the thermostat). It's always a bit too warm upstairs and a bit too cool downstairs UNLESS I kick on our ventless logs in the family room (where the thermostat for the furnace is). THEN the furnace basically locks out because it gets so warm in that room and it's FREEZING upstairs by the time we go to bed. If down the road I went to zoning, THEN would the variable speed blower be a Godsend?

    4. Should I DOWNSIZE the furnace from 125,000 to 100,000 based on the increase in efficiency? There is very little price difference.

    5. Am I nuts to be considering replacing only the furnace and not the AC unit? Cinergy increased are power rates by about 10% last year. I guess I'm in the 7-cent a KWH range now. The compressor is at least 10 years old and actually predates the furnace I'm going to take out.

    Sorry this got so long. Any thoughtful advice would be mucho appreciated.

    THANKS!

    Phil

  2. #2
    Join Date
    Jan 2002
    Location
    Ft.Worth,Tx
    Posts
    4,584

    Unhappy Good BUY Variable Drive..

    1) The price for variable drive is $400.00 difference and you don't see the savings..
    First thing to remember is there is variable drive not multi speed.Multi-speed has high for air condtioning and low for heat.
    Variable Drive adjust to dip switch settings inside the furnace,and most 90% furnaces have (2) stages of fire.
    A) Low stage is first called on thermosat and if single stage thermostat, after 10 minute of operation thermostat still calling for heat, unit stops and fires to second stage . As for the blower the variable drive design is very quiet as is ramps up according to settings, so you can watch t.v........

    Savings in this area are from 12-17% on 2 stage variable, but this is Texas and we don't get very cold here...
    "Everyday above ground, is a good day".
    "But everyday that you have made a difference in someones life, may insure you stay above ground a little longer".<aircooled>

  3. #3
    I think that you have a unique situation there,and that it would probably do you a lot of good to at least have a professional come and perform a heat loss\gain evaluation of your home.

    This is the first step to take. If your are serious about installing the right equipment, and getting the most fuel efficeint system available for your home.The bells and whistles are other options and accessories that are available to enhance your system,but they will not mask or compensate for errors made during the time that you choose the size and style of your equipment.

  4. #4
    Join Date
    Feb 2004
    Posts
    2,597
    phil,

    1. go to the fireplace forum for more info on your un-vented gas logs. many feel they are unsafe.

    2. have a load calculation done on your home. just because a 125,000 was put in beforehand does not mean it was right.

    3. click the target at the top of the page for a low cost version of the load calc.

    4. start researching your options so you know what you want when you finally call a contractor, and keep reading this site for some good info to make a wise decision.

    5. quality, is not inexpensive.

    good luck

  5. #5
    Join Date
    Jan 2005
    Location
    Seattle
    Posts
    191

    Cool 90+%furnace

    hoos1erbud.
    to answer you questions.
    The 90+% furnaces are one
    FRECKEN less noisy than that
    125,000btu duel turbocharged,
    supercharge,Boeing jetpowered
    747 heicopter furnace you got
    powering your place right now!!!!
    I really do know what you mean.
    When a 80% 125,000 furnace lights
    off it will make you jump.The
    only thing that saves the old ticker
    is that the inducer motor noise
    let you know its coming.

    Anyway enough of the funnys.
    The 90% are very quiet because
    all the fire is in a box.
    The second thing you want to make
    sure you have is the two pipe
    venting system.One for the
    combustion air and one for the
    exhaust.Some installers only
    run the exhaust out of the house
    but use the air from inside the
    house for the combustion. This
    is not good.BECAUSE it creates
    a draft.That cold breeze you
    probably feel when the furnace
    is running.all that air going
    out the out pipe is coming
    from somewhere you know.
    Next thing yes yes yes the
    V/S blower is worth the money
    with out question to me.
    They are quite,Very energy
    efficient.Cost about the
    same as a 60 watt light
    bulb to run in the continuous
    fan mode. this is what you
    want so you can set your
    self up a with a really good
    filtration system.Also the
    V/S do a really good job
    in combination with you a/c
    to help with the dehumidification
    the motor has the ability to
    ramp doen the air speed
    leting the air spend alittle
    more time on the coil.THis
    helps a lot to pull the
    water out of the air.
    The two stage furnace
    in general are good because
    it give you the total capacity
    in high gear to keep you and
    yours toasty warm during the
    coldest nights.Yet will spend
    ninty percent of the time just
    plugging along in low gear
    during your average "it just
    a little chilly out" times.
    I don't sell Heil furnaces
    but I always tell people
    who buy the V/S's to but
    the ten year warrenty.The
    part and labor are covered
    that way so any repairs on
    that cool motor are no big
    deal.The to stage inducer
    motor well..... that is
    just part of a good furnace.
    Now hold on to your shorts
    because there are some pretty
    strong opinions here about
    V/S motors.Also make sure you
    have a good load calc done
    on your home before installing
    anything.You seem to have a wierd
    set up now.I have never seen a
    125,000 btu furnace in a four ton
    always five ton. But you say
    you have a four ton a/c...?
    Good luck.
    41Gasman




  6. #6

    Thumbs up Thanks everyone

    Hey everyone...thanks for the information.

    Regarding the 4 ton thing...I have no idea WHY I think it's a 4-ton unit. That's just what I've had in the back of my mind. The only thing I've ever done to it is mow around it...so that probably means I'm just WRONG.

    Regarding the ventless heaters (logs) I have a set of logs and a small ventless spaceheater in an enclosed porch area in my home. I've been using ventless products for about 12 years now and I think I appreciate their limitations. Where I work, they actually service and sell them...and they DO have their limitations. However, in my 1.2 decades of experience owning them...they're fine if you only use them a couple of hours a day...and always always always turn them off before you have any kind of solvent (paint, glue, etc.) within a quarter mile of them. The more I live with them...actually the LESS I like them...but I could say that about my ex-wife too, right?

    Seriously...they're OK. Not great...not good...but better than wood.

    On the furnace sizing issue...I had better check that a/c unit size...because I realize I don't want to have a furnace that is too small to handle the a/c. The OLD 1960 furnace I took out was 200,000 BTU's!!! The other thing is, my ductwork sucks eggs. This house got natural gas service in 1960...42 years after it was built. I'm pretty sure it was originally heated with an oil furnace of some kind. I don't know if the ductwork dates that far back...probably more like to the early 40's. It's galvanized on the hot side. The return air is mostly just boxed in floor joists.

    The other thing I should own up to is I paid well under 100K for this house...and it probably wouldn't bring 100K now in this area. So, it's not like I can drop 20 grand on a HVAC system WITH new ductwork. No matter what I do, the exterior wall insulation is iffy, there's no house wrap, and CURRENTLY there's no insulation in the basement (which has about 28" exposed on all 4 sides of the house.

    I guess my point is...if I spring for a 92% afue furnace...then it's going to be the best part of my whole system. I'd actually rather undersize it a bit rather than oversize it...because I'll pick up more BTU when I get around to insulating the basement. Of course a 92% 100K BTU furnace is ALMOST as big as a 80% 125K BTU furnace anyway.

    Thanks again everyone for your advice.

    Oh...one more thing...the Heil comes with a 5 year warantee...but they extend it to 10 for more money. I'll find out what a new motor costs and see if it is more than the extended contract. If so...the contract would be a bargain.

    Phil


    [Edited by hoos1erbud on 03-04-2005 at 07:44 PM]

  7. #7
    Join Date
    Feb 2003
    Posts
    275
    there is a good contractor in New Albany, call him

  8. #8
    Phil,

    There are a lot of reasons to do it the inexpensive way,I'm sorry that we could not convince you that having it done by or at least having a professional size it for you was a worthwhile investment,your scenario is one that we see all the time, and more often then not we see it lead to unecessary repairs and an uncomfortable home over the life of the equipment.

  9. #9
    I appreciate what you are saying.

    I'm a little better off than the worst offenders because I am fortunate to have two guys working for me that I hired away from HVAC work. One did it for 15 years. One did it for 10. I had the guy who did it for 15 over for lunch today. He got free chili and a look at my situation. He suggests 125K to make sure it's big enough.

    I agree that it would be nice to have a load sizing done.

    At the same time though I'm skeptical. How could they adequately model my exterior walls? It's aluminum siding over a styrofoam bat over wood siding over dimensional poplar framing with lathe and plaster that has been filled with blown in cellulose to some degree. What degree?

    Do they take actual measurements on heat loss?

    Same thing on the attic insulation, degree of sealing around windows, uninsulated floors over a small crawlspace area, etc. etc. etc. All of these issues could make a huge difference in the heat load. Speaking of heat load, what about the parasitic heat load from all of the computer equipment and appliances?

    It seems to me that it would be A LOT easier to calculate this for a new house where all of these factors were known than guess at them for an old house. But, I freely admit I haven't ever done this type of work...so I could be completely wrong.

    Phil

  10. #10
    Phil

    I agree that there are a lot of variables to contend with,and that is what makes your home unique.The various types and configuration of materials used in your home will make assessing your loads a challenge, even for a well experienced estimator.That is why I recommended that you have the assessment done first,although it would be challenging it promises to be more accurate than dong it by comparison of an existing unit.

    When you sart your new furnace you will find that its operation hardly resembles the unit you are removing,and will not run appropriately enough to provide comfort to the whole dwelling if it is mis-sized by very much on either the low side or the high side.A true evaluation will provide a good assessment of what type of unit to use and may result in the best choice of unit\brand to accomadate the existing duct system.

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