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  1. #27
    Join Date
    Jul 2011
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    71
    Quote Originally Posted by AC Bad Dog View Post
    It's sounds to me you are really not that concerned with comfort, or why not fix the crappy windows?
    This year: new granite kitchen counters, new microwave, new dishwasher, raised kitchen cabinets to new floor level, new A/C, new countertops in all three baths, full-time summer daycare, prepayment of private school tuition, needed to get a new car, refinanced mortgage, summer vacation, downpayment on winter vacation, and now new furnace.

    :-) That's why!

  2. #28
    Join Date
    Jul 2011
    Location
    Saskatoon, Canada
    Posts
    25
    This may seem a little simple but as I do not know where you live I often ask people if their old furnace ran steady on the coldest days of the year. It does not bypass load calculations but is a little common sense test when all else fails. I have the 355aav and it has been trouble free. As someone noted make sure you have the two pipe venting done as using outside air cuts down on flame sensor and ignitor problems the haunt midefficient furnaces. I have the evolution thermostat on use the single stage system.I live in Canada and I rarely go to high fire except after setback.

  3. #29
    Join Date
    Aug 2011
    Posts
    568

    Confused

    Quote Originally Posted by beenthere View Post
    He's probably happy, cause he doesn't know how much better it would be with the smaller size furnace. Many people do live the philosophy ignorance is bliss.
    hey global, i got a philosophy in life, if it ain't broke, don't fix it! if the customer is happy, let it go! i see enough people on these boards, that are unhappy, with there installs,leaks from day one,capacitors that blow out once a month,unit won't cool on a hot day etc. so when a customer/h/o is satisfied and happy, i smile and leave! that's just me. p.s. years ago a old girl friend, got a hair cut. a real twiggy look, if you remember twiggy, she loved the cut, unfortunately no one else did. she says to me how do i like her hair cut? i said "don't like it". should of left it alone!
    like i said, if the customer is happy,pick up the check, say thank you,and leave! but that's just me!

  4. #30
    Join Date
    Sep 2002
    Location
    I don't know
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    2,904
    ^There is absolutely no benefit associated with oversizing.

    It's cheaper in the short and long run to install the smallest unit which will do the job with a small safety factor. (all furnaces have a safety factor since they're usually sold in 15-20k btu increments) It's not as if the 80k unit is cheaper. (on the contrary, oversizing defeats the purpose of getting a 2-stage unit to begin with - what's the point if it will cycle off after a few minutes, even on low fire?)

    A accurate load calc will tell you which size is required.

    As for windows, I agree with you - the ROI of replacing existing double pane windows is probably very poor.
    General public's attitude towards our energy predicament: "I reject the reality of finite resource depletion and substitute it with my own; energy is infinite, we just need an alternative storage medium to run the cars on. The economy can grow indefinitely - we just need to "green" everything! Technology is energy! Peak what?"

  5. #31
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,314
    Quote Originally Posted by MM#7 View Post
    hey global, i got a philosophy in life, if it ain't broke, don't fix it! if the customer is happy, let it go! i see enough people on these boards, that are unhappy, with there installs,leaks from day one,capacitors that blow out once a month,unit won't cool on a hot day etc. so when a customer/h/o is satisfied and happy, i smile and leave! that's just me. p.s. years ago a old girl friend, got a hair cut. a real twiggy look, if you remember twiggy, she loved the cut, unfortunately no one else did. she says to me how do i like her hair cut? i said "don't like it". should of left it alone!
    like i said, if the customer is happy,pick up the check, say thank you,and leave! but that's just me!

    Yes, there are many 'thats good enough" contractors around.

    Clocker doesn't have his new system installed yet. So no telling if he will be happy with the larger over sized unit.

    I may not know exactly where in Michigan he lives. But over sized furnaces there, work the same as they do here.

    Over the years, there has been m any people that have come back here and said they wish they had taken the advise of the majority of the members here, and not over sized.
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  6. #32
    Join Date
    Jul 2011
    Posts
    71
    Did you guys come over and do a precise load calculation over-night for me to be able to say with such certainty that the proposed system is oversize? Truth is you have no idea because you haven't done a load calculation, either. Or is your intuition that good that you don't need a load calc? Doesn't sound any different than 99% of the contractors out there.

    I'll bet 90% of the guys on this forum don't always practice what they preach and that 75% of the calcs. that actually are done are probably wrong anyway.

    Real world experience with a home almost identical to mine will be better than any load calc. unless the calc is performed by someone who really knows how to do it and is familiar with my surroundings and weather. We'll see what my other contractors say though.

  7. #33
    Join Date
    Sep 2002
    Location
    I don't know
    Posts
    2,904
    Did you guys come over and do a precise load calculation over-night for me to be able to say with such certainty that the proposed system is oversize? Truth is you have no idea because you haven't done a load calculation, either. Or is your intuition that good that you don't need a load calc? Doesn't sound any different than 99% of the contractors out there.
    I don't know what you're climate is like or how well built the house is, but with a design temp around -10F and R30+ attic/R12+ above ground walls/insulated basement, a 80 k unit (100k mid efficiency equivalent!) is sufficient for a larger 2 story house - sometimes over 3000**** sq ft.

    ****Factors which could render that statement completely invalid: High ceilings, excessive air leakage, ductwork in unconditioned space, high window surface area, plus much more. Do not take my word for it.




    Experience doesn't mean anything unless you know for a fact that it runs continuously on low in extreme cold (does it?), switching to high occasionally. If a 2-stage shuts off at all near design conditions, either it's connected to a single stage t-stat or it's grossly oversized.

    Having 2-stages of heat can make a 40%+ oversized unit seem okay based on experience.
    General public's attitude towards our energy predicament: "I reject the reality of finite resource depletion and substitute it with my own; energy is infinite, we just need an alternative storage medium to run the cars on. The economy can grow indefinitely - we just need to "green" everything! Technology is energy! Peak what?"

  8. #34
    Join Date
    Mar 2010
    Posts
    195

    There is no such thing as a "Precise Load Calculation"

    Quote Originally Posted by Clocker View Post
    Did you guys come over and do a precise load calculation over-night for me to be able to say with such certainty that the proposed system is oversize? Truth is you have no idea because you haven't done a load calculation, either. Or is your intuition that good that you don't need a load calc? Doesn't sound any different than 99% of the contractors out there.

    I'll bet 90% of the guys on this forum don't always practice what they preach and that 75% of the calcs. that actually are done are probably wrong anyway.

    Real world experience with a home almost identical to mine will be better than any load calc. unless the calc is performed by someone who really knows how to do it and is familiar with my surroundings and weather. We'll see what my other contractors say though.
    Yo Clocker, Calm down now..

    First,
    No one can do a "Precise Load Calculation", that is impossible on many levels. Even when tests are preformed we simply lower our +- tolerances.

    Second,
    As AMD has correctly stated, a load calc is only as good as the inputs.With and old "leaky" house like yours these inputs are impossible to even be close on with out testing your homes leakage, and system losses. So, on old houses, we basically agree, "75 % of the calcs...are wrong". Or we don't even know.

    Third.
    Even though you say it sarcastically, "Or is your intuition that good that you don't need a load calc?" This is actually quite true for the best contractors out there.They have designed hundreds if not thousands of systems for homes just like yours. Place more value on their experience than anything. The load calc act, can actually be a crutch for guys with less experience, and as previously stated, garbage in,,,etc.

    Forth.
    You make the statement "'ll bet 90% of the guys on this forum don't always practice what they preach". I can't say for sure on this, but think about it, these guys are trying to help you, they are not getting paid to do it, and they are doing this on their own time. You may not agree with some of their comments, but can you at least thankful they are here? Right?

    Fifth.
    You go on to say "75% of the calcs. that actually are done are probably wrong anyway." So, here is the Deal. The "load" on your house is a constantly changing number,never the same for more than a second. Sometimes there is no load and sometimes you have more load than any one ever figured would happen. It is a moving target, no one answer. That is why you will love a Modulating Furnace. Why? Duh, Because it Modulates. As the load changes the machine continuously changes its capacity to match the load. With the two stage unit, what the guys are telling you, is that if your load never gets above the 1st stage output, you never get to experience the comfort this unit can provide.Again, they are trying to help you.

    Sixth.
    You go on to say "Real world experience with a home almost identical to mine will be better than any load calc." To a degree, this is true as well.
    If the other home is identical in size, type, and vintage, and the furnace is running on 1st stage 84% of the time and just keeping up on the coldest day you could make this case. One Note: Never trust a neighbor.

    As I see it, you have two choices:

    1. Do it right.
    Get your Ducts tested, and your Home's infiltration rates confirmed with a Blower Door. As I said you will be shocked with these results. You will now now have some credible information to base your decisions on. You will find the ROI on Duct retrofits, and Air leakage much higher than the furnace. Doing these projects together is best. If you don't address your leaky home directly you simply pay for these improvements in your gas bill(but you don't get them). You are not saving money by not making the first order improvements.

    2. Fly by the seat of your pants.
    This is what the vast majority do. Get the bigger furnace and it will blow all the hot air you need.

    I am now done blowing hot air,

    good luck,

    ACBD

  9. #35
    Join Date
    Aug 2011
    Posts
    568

    Smile

    Quote Originally Posted by beenthere View Post
    Yes, there are many 'thats good enough" contractors around.

    Clocker doesn't have his new system installed yet. So no telling if he will be happy with the larger over sized unit.

    I may not know exactly where in Michigan he lives. But over sized furnaces there, work the same as they do here.

    Over the years, there has been m any people that have come back here and said they wish they had taken the advise of the majority of the members here, and not over sized.
    hey global do you belive in MANUEL J CALCULATIONS, YES OR NO?

  10. #36
    Join Date
    Aug 2007
    Posts
    72
    Quote Originally Posted by MM#7 View Post
    go with # 2 the high efficency motor uses about 1/2 the electic as a standard motor!
    When that high-efficiency motor needs replacing, how much will that cost, compared to a standard motor?

  11. #37
    Join Date
    Aug 2011
    Posts
    568

    Confused

    Quote Originally Posted by PowerPlay View Post
    When that high-efficiency motor needs replacing, how much will that cost, compared to a standard motor?
    usually that motor comes with a 10 year warranty, but after warranty, it ain't cheap, that's a question you'd ask the installer! but i like your thought process as far as it great that they have this hi tech stuff, but when it breaks down how much is it going to cost? most h/o don't ask those questions until it breaks down out side oof warranty. just another factor among many for all to consider!

  12. #38
    Join Date
    Mar 2010
    Posts
    195

    So, should the tech make the economic decision for the homeowner?

    Quote Originally Posted by MM#7 View Post
    usually that motor comes with a 10 year warranty, but after warranty, it ain't cheap, that's a question you'd ask the installer! but i like your thought process as far as it great that they have this hi tech stuff, but when it breaks down how much is it going to cost? most h/o don't ask those questions until it breaks down out side oof warranty. just another factor among many for all to consider!
    OK,

    So, Lets say home owner makes 400k/yr. Lets say HVAC guy makes less.

    When should HVAC guy start making economic and comfort decisions for the homeowner?

    Should he survey homeowner as to their financial status before quoting systems? Lets have a look at your ductwork and your Stock Portfolio before we quote this job.

    Thinking the customer has no money is a great way to make less yourself.
    Keep talking them out of the good stuff, and you just end up quoting price on commodities.

    How about we just let the customer choose? Our job is to create choices not make choices. We do not know what is important, or two expensive.

    Perfect,

    ACBD

  13. #39
    Join Date
    Jul 2011
    Posts
    71
    ABCD- I agree with you 100%. I am very appreciative of those who are volunteering to help, as I have stated more than once.

    Only thing I take exception with is some of the conclusions being drawn here that are based on nothing more than a guess. Nobody here really knows if an 80K BTU furnace is oversize for me but several members sure act as if they know that with certainty with only a small bit of knowledge about the situation. That's not good advice. I'd say it's worse than the advice I would get from any joe-contractor who doesn't run a Manual J. At least he would see the house and my existing furnace.

    I think the only useful advice regarding furnace size that can be given in a forum like this is that you should get a Manual J if you really want size your furnace right and try not to oversize but don't let yourself get too undersize, either. Maybe they need to make more sizes....60,70,80,90,100 etc.

    Nobody really talks about the risk of undersizing. I 've been very happy with the performance of my 80K/80% furnace. It doesn't blast me out but it heats the house quick enough when I get home from work and I notice it running for relatively long periods on cold days. If I go to a 60K/95% furnace, I'll lose 7K BTU in peak output. What if the house doesn't get warm enough or heat up fast enough on those cold days? I'd hear it from my wife because I didn't listen to joe contractor and tried to cheap out or over-optimize the furnace. :-)

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