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  1. #14
    Join Date
    Jul 2008
    Location
    Rochester NY
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    Quote Originally Posted by Maikerum View Post
    The reason is that I like to do a night setback and drop the temp from 71 to 65 overnight. Most nights the temp only drops to 66-68 overnight, though on very cold nights it will go down to 65 by morning.
    Why do you like to do that?

    Quote Originally Posted by Maikerum View Post
    Right now the furnace runs about twice as often in low stage as in high, and I would prefer it to be locked in high to get maximum efficiency for that short period of time in the morning the furnace runs.
    Why would you prefer that? What do you mean by maximum efficiency?

    My manual J had my heat loss at design conditions to be 34,000. So it is true I could get by with only low stage, but why use the furnace at its least efficient?
    Why would you think that's least efficient?

    What is your static pressure at low, and high?
    What is your duct leakage at low? At high?
    What pressure imbalances occur in your rooms at low? At high?
    How much pressure induced leakage is occurring at low fire? At high?
    How much heat gets delivered to occupied space per therm burned on low? How much on high?
    And at what temperature is comfort achieve with a low fan rate? How much warmer must the setting be for a rapidly cycling high blowing fan rate?
    You aren't buying temperature, you are buying comfort. http://bit.ly/comfortcalculator

    If you look at this just looking at one tiny slice, it's like your nose is pressed up against a work of art. Would you really do THAT and think you were seeing the whole picture?
    Last edited by tedkidd; 12-01-2012 at 10:42 PM.
    Which makes more sense to you?
    CONSERVATION - turning your thermostat back and being uncomfortable. Maybe saving 5-10%
    ENERGY EFFICIENCY - leaving your thermostat where everyone is comfortable. Saving 30-70%

    DO THE NUMBERS! Step on a HOMESCALE.
    What is comfort? Well, it AIN'T just TEMPERATURE!

    Energy Obese? An audit is the next step - go to BPI.org, or RESNET, and find an auditor near you.

  2. #15
    Join Date
    Jul 2008
    Location
    Rochester NY
    Posts
    4,736
    Here's a GREAT article by Dan Holohan that helped put things into perspective for me:

    http://bit.ly/danholohan1992
    Which makes more sense to you?
    CONSERVATION - turning your thermostat back and being uncomfortable. Maybe saving 5-10%
    ENERGY EFFICIENCY - leaving your thermostat where everyone is comfortable. Saving 30-70%

    DO THE NUMBERS! Step on a HOMESCALE.
    What is comfort? Well, it AIN'T just TEMPERATURE!

    Energy Obese? An audit is the next step - go to BPI.org, or RESNET, and find an auditor near you.

  3. #16
    Join Date
    Jul 2009
    Location
    Columbia, MD
    Posts
    4,036
    tedkidd. You seem really intelligent. But, when someone as myself has proof that a 2 stage furnace causes the utility bill to go up and the home owner is not comfortable I think differently.

    One customer in particular had a 150,000btu furnace that i replaced with a 2stage 60,000 btu furnace with honeywell iaq stat. Not only was she not comfortable with 1st stage but, her gas bills went up to. The correct fix was to lock the furnace in high fire. After the fix her gas bills went down and she was comfortable again. This was a 150,000 80% furnace replaced with a 2stage 60,000 80% furnace. How could her bills go up when i took a furnace out that was twice the size? The new furnace was sized for the home. So it's not like I put in a undersized furnace. There are many more stories like this. You can preach all your talk. But when I have hard facts and proof I will continue to do things the proper way and make people aware.

  4. #17
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    68,171
    Quote Originally Posted by gravity View Post
    tedkidd. You seem really intelligent. But, when someone as myself has proof that a 2 stage furnace causes the utility bill to go up and the home owner is not comfortable I think differently.

    One customer in particular had a 150,000btu furnace that i replaced with a 2stage 60,000 btu furnace with honeywell iaq stat. Not only was she not comfortable with 1st stage but, her gas bills went up to. The correct fix was to lock the furnace in high fire. After the fix her gas bills went down and she was comfortable again. This was a 150,000 80% furnace replaced with a 2stage 60,000 80% furnace. How could her bills go up when i took a furnace out that was twice the size? The new furnace was sized for the home. So it's not like I put in a undersized furnace. There are many more stories like this. You can preach all your talk. But when I have hard facts and proof I will continue to do things the proper way and make people aware.
    Don't think I ever put in a 2 stage that used more fuel. A few were installed using the timer to go to second stage. The rest were controlled by the stat. All were set up by CA and to factory specs for allowable temp rise.
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  5. #18
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    I think that customer was an annomoly. Irrational might best describe her. Seth was likely trained to correlate the sound and blast of higher temp air with feeling warm and enjoyed larger temp swings. I otoh am sitting here now a little chilly waiting for my 100k to cycle on and wishing for a smaller 2 stage or dual fuel that would be running almost constantly below 50f.

    Sent from my DROID RAZR using Tapatalk 2

  6. #19
    Join Date
    Jul 2008
    Location
    Rochester NY
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    Quote Originally Posted by gravity View Post
    tedkidd. You seem really intelligent. But, when someone as myself has proof that a 2 stage furnace causes the utility bill to go up and the home owner is not comfortable I think differently.

    One customer in particular had a 150,000btu furnace that i replaced with a 2stage 60,000 btu furnace with honeywell iaq stat. Not only was she not comfortable with 1st stage but, her gas bills went up to. The correct fix was to lock the furnace in high fire. After the fix her gas bills went down and she was comfortable again. This was a 150,000 80% furnace replaced with a 2stage 60,000 80% furnace. How could her bills go up when i took a furnace out that was twice the size? The new furnace was sized for the home. So it's not like I put in a undersized furnace. There are many more stories like this. You can preach all your talk. But when I have hard facts and proof I will continue to do things the proper way and make people aware.
    If you start seeing causation in correlation, the jump to building science hvac contractor will be really tough.

    Can I see the audit data? I have seen the problem Moto suggests, but havent seen that lead to noticeable energy consumption. I'd like to make sure it's not the enclosure.

    If you didn't do a complete audit, blower door, square footage, and bill analysis?

    Love duct blaster testing, I suspect significant duct leakage to outdoors, if what you say is true. If you attempt to heat the outdoors, longer run cycles cost rather than saving.
    Which makes more sense to you?
    CONSERVATION - turning your thermostat back and being uncomfortable. Maybe saving 5-10%
    ENERGY EFFICIENCY - leaving your thermostat where everyone is comfortable. Saving 30-70%

    DO THE NUMBERS! Step on a HOMESCALE.
    What is comfort? Well, it AIN'T just TEMPERATURE!

    Energy Obese? An audit is the next step - go to BPI.org, or RESNET, and find an auditor near you.

  7. #20
    Join Date
    Sep 2009
    Location
    Arnold mo
    Posts
    3,969
    Quote Originally Posted by tedkidd View Post
    If you start seeing causation in correlation, the jump to building science hvac contractor will be really tough.

    Can I see the audit data? I have seen the problem Moto suggests, but havent seen that lead to noticeable energy consumption. I'd like to make sure it's not the enclosure.

    If you didn't do a complete audit, blower door, square footage, and bill analysis?

    Love duct blaster testing, I suspect significant duct leakage to outdoors, if what you say is true. If you attempt to heat the outdoors, longer run cycles cost rather than saving.
    +1. A great example of why the "whole House" approach is necessary. Blower induced air infiltration/exfiltration can cause significant energy waste, not just through duct leakage, but also from pressure imballances caused by improper air flow through the home. This is also a great example to show that you cannot solve a homes energy & comfort issues with equipment alone.
    An answer without a question is meaningless.
    Information without understanding is useless.
    You can lead a horse to water............
    http://www.mohomeenergyaudits.com

  8. #21
    Join Date
    Sep 2006
    Posts
    57
    Just curious, whats elevation is this builing at? Don't forget to derate. 4% per 1000 ft of elevation when talking numbers.

  9. #22
    Join Date
    Jun 2010
    Location
    Charlotte, NC
    Posts
    155
    [/COLOR]
    Quote Originally Posted by tedkidd View Post
    Why do you like to do that? (Use night setback, that is.)

    I like sleeping in a cool room. Makes my cats (and wife) friendlier.


    Why would you prefer that? What do you mean by maximum efficiency?

    I would prefer high heat during recovery because I want a rapid warmup from 65 night setting to 71 morning shower setting. I want the house warm fast, I want warm air keeping bath mirrors defogged, and I like hearing that comforting whoosh of the furnace firing up 15 minutes before I get out of bed.

    Why would you think that's least efficient?

    While gravity made a mistake in calculating first stage efficiency by dividing low stage output by high stage input, my understanding is furnaces are somewhat more efficient at full capacity, though not as much as he had it.

    What is your static pressure at low, and high?
    Those are the numbers I posted, wanting a interpretation of.

    What is your duct leakage at low? At high? A little more at high I guess, but probably not much either way. My ducts are mastic sealed.

    What pressure imbalances occur in your rooms at low? At high? I think at high I find further rooms get more heat, so the house is more even. I don't think I have much in the way of pressure imbalances.

    How much pressure induced leakage is occurring at low fire? At high?
    How much heat gets delivered to occupied space per therm burned on low? How much on high? I think on low, more of the heat lingers in the ducts in my unheated crawlspace, getting wasted there, and more gets to occupied space on high.
    And at what temperature is comfort achieved with a low fan rate? How much warmer must the setting be for a rapidly cycling high blowing fan rate? In my particular 1750 sf house, originally with a 3 ton ac and bigger furnace that I replaced with 2 ton a/c and smaller furnace, even at 1,000 cfm on high stage heat, it is not very drafty. That 1000 cfm is divided among 13 baseboard vents each supplied by 6 inch round metal ducts (One duct run for a bath is five inch). I sometimes wonder if I have enough velocity to get good thermal mixing, especially on low.You aren't buying temperature, you are buying comfort. http://bit.ly/comfortcalculator

    If you look at this just looking at one tiny slice, it's like your nose is pressed up against a work of art. Would you really do THAT and think you were seeing the whole picture?
    Thanks

  10. #23
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    Jan 2004
    Location
    Lancaster PA
    Posts
    68,171
    Depending hop dirty the air filer is, your second stage heat static is a bit high. then again, your temp rise is a bit low at that CFM.

    If the second stage CFM were dropped to 1,000 CFM even, you would get a better temp rise and lower static.
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  11. #24
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    Jul 2008
    Location
    Rochester NY
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    Quote Originally Posted by Maikerum View Post
    [/COLOR]

    Why do you like to do that? (Use night setback, that is.)

    I like sleeping in a cool room. Makes my cats (and wife) friendlier.
    If the house typically only drops to 68 that must be comfortable, maybe that'd be a better setback.
    Why would you prefer that? What do you mean by maximum efficiency?

    I would prefer high heat during recovery because I want a rapid warmup from 65 night setting to 71 morning shower setting. I want the house warm fast, I want warm air keeping bath mirrors defogged, and I like hearing that comforting whoosh of the furnace firing up 15 minutes before I get out of bed.
    Whoosh? My clients hear NOTHING. Most have to go to the basement and put their hands on the furnace to figure out if it's running. Fast recovery is NOT efficient. It's hitting the pedal to the metal when getting on the highway. Moisture forms on your mirror due to due point temperature. The colder you let your house get, the more visible and invisible surfaces there are that will be at dew point, and the greater your risk of mold, mildew, and rot.
    Why would you think that's least efficient?

    While gravity made a mistake in calculating first stage efficiency by dividing low stage output by high stage input, my understanding is furnaces are somewhat more efficient at full capacity, though not as much as he had it.
    Look at the manufacturers ratings. Then look at fan curve and calculate your ECM draw at .27 and at .78. That might help you understand where you could save energy needlessly wasted.
    What is your static pressure at low, and high?
    Those are the numbers I posted, wanting a interpretation of.
    Too high on high. Good otherwise. I like to see between .1 and .4 - check out Fans law to understand geometric cost of flow at higher pressure.
    What is your duct leakage at low? At high? A little more at high I guess, but probably not much either way. My ducts are mastic sealed.
    An audit would help you understand where you can reduce waste.
    What pressure imbalances occur in your rooms at low? At high? I think at high I find further rooms get more heat, so the house is more even. I don't think I have much in the way of pressure imbalances.
    Typically the reverse is true. Hi heat means faster thermostat satisfaction and LESS uniform distribution.
    How much pressure induced leakage is occurring at low fire? At high?
    How much heat gets delivered to occupied space per therm burned on low? How much on high? I think on low, more of the heat lingers in the ducts in my unheated crawlspace, getting wasted there, and more gets to occupied space on high.

    An audit would help you understand where you can reduce waste.



    And at what temperature is comfort achieved with a low fan rate? How much warmer must the setting be for a rapidly cycling high blowing fan rate? In my particular 1750 sf house, originally with a 3 ton ac and bigger furnace that I replaced with 2 ton a/c and smaller furnace, even at 1,000 cfm on high stage heat, it is not very drafty. That 1000 cfm is divided among 13 baseboard vents each supplied by 6 inch round metal ducts (One duct run for a bath is five inch). I sometimes wonder if I have enough velocity to get good thermal mixing, especially on low.You aren't buying temperature, you are buying comfort. http://bit.ly/comfortcalculator

    If you look at this just looking at one tiny slice, it's like your nose is pressed up against a work of art. Would you really do THAT and think you were seeing the whole picture?


    Thanks
    You are welcome!
    Which makes more sense to you?
    CONSERVATION - turning your thermostat back and being uncomfortable. Maybe saving 5-10%
    ENERGY EFFICIENCY - leaving your thermostat where everyone is comfortable. Saving 30-70%

    DO THE NUMBERS! Step on a HOMESCALE.
    What is comfort? Well, it AIN'T just TEMPERATURE!

    Energy Obese? An audit is the next step - go to BPI.org, or RESNET, and find an auditor near you.

  12. #25
    Join Date
    Jun 2010
    Location
    Charlotte, NC
    Posts
    155
    Thanks again, Teddkid, Beenthere, and Gravity. I will take some of all your advice, and the debate has been instructional.

    I will see if I can lower cfm, first, just to 1000 from 1033, and then see how it does at 950. Hopefully that gets me near .5 static pressure.

    Since it has only run on high fire 250 hours (lifetime service hours, I love the data this stat makes available) over two winters I am probably quibbling anyway. It has run on low fire 517 hours, the rest on heat pump. So it runs on high fire 4% of winter hours, low fire 8% of the time and off or in heat pump mode the rest.

    I will think about locking it in high fire. I like the fast option for morning warmup, but I do want it to be capable of low fire on really cold days when I want to maintain temps.

    As far as an audit goes, I had a free one from the utility, just a walk-through, no duct leakage or house sealing testing.

    But they could not find a lot. I installed house wrap very carefully and sealed around windows when I resided the house a few years ago.

    Last year I airsealed my attic and crawl space, and spent several weekends applying goopy mastic to ducts and then wrapping with insulation. I am big into building science. At each step, I could tell a huge difference. For example, after air sealing my attic, my bills went down, but in addition, I did not have to use a humidifier last winter on cold dry windy days as I used to have to do.

    I have found that Teddy Bear was right in that keeping humidity under 50%, my son's dust mite allergy went away.

    On your homescale, TeddKidd, it was a bit difficult since it is not made for dual fuel, but I converted my gas use to kWh and have a total annual energy use of 16,167 kWh. That put me a touch below "high efficiency home." My annual energy use of 16,167 includes heat, cooling, lights, hot water, everything. My bills over a year for gas and electric combined is $1200, about half of which is heating and cooling, so even if I can find a way in this old 70's house to cut another 20% on heating and cooling, that's only $120 a year. So I am going to skip the duct blaster and air leak testing. If I seal too tight, I won't get any air changes.

    The bathroom mirror only fogs up when I am taking a shower, not overnight when the heat is off. So I am not overly concerned with moisture damage to my house--I keep an eye on relative humidity indoors, and have good bath and kitchen vents.

    It probably would be cheaper if I kept the house a constant temp 24-7, so the heatpump did all the work, rather than have the night setback, but the difference was about $30 a year. For $30 a year, I am going to enjoy the cool sleeping hours and the wonderful whoosh of that furnace reminding me I got fifteen more minutes. Since the furnace is in a closet across from my bedroom and between my sons' bedrooms, not much chance I will hear nothing. But I like that sound--it is not loud, and it is comforting.

  13. #26
    Join Date
    Jul 2008
    Location
    Rochester NY
    Posts
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    I have only anicdotal understanding of what energy use in Charlotte is, that said yours sounds like very low energy use. $120 month?

    Also sounds like the furnace operation is practically irrelevant (that static is not though - ecm's last longer if you don't burn them up...)

    Your air sealing efforts have probably dramatically reduced mold, mildew, rot risk. Typically those problems occur when large amounts of humid air (driven by stack pressure) come continuously in contact with dew point surfaces. Would be good to get a blower door test. Nice to know the number.

    I like/applaud your decision not to obsess about saving a small amount of energy vs satisfying comfort preferences. Late to work once might cost $30.
    Which makes more sense to you?
    CONSERVATION - turning your thermostat back and being uncomfortable. Maybe saving 5-10%
    ENERGY EFFICIENCY - leaving your thermostat where everyone is comfortable. Saving 30-70%

    DO THE NUMBERS! Step on a HOMESCALE.
    What is comfort? Well, it AIN'T just TEMPERATURE!

    Energy Obese? An audit is the next step - go to BPI.org, or RESNET, and find an auditor near you.

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