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  1. #14
    Join Date
    Feb 2012
    Location
    Michigan
    Posts
    87
    This is the Ask Our Pro's forum, and only Pro members that have been vetted by the AOPC may post advise, commentary or ask questions of the OP here. Please apply to the AOPC today, thank you.

    You can find the rules for posting and qualifications here.

    Further infractions may result in loss of posting privileges.
    Last edited by beenthere; 10-03-2012 at 04:46 PM. Reason: Non Pro * Member

  2. #15
    Join Date
    Feb 2005
    Posts
    46
    Quote Originally Posted by Homeowner314 View Post
    This is the Ask Our Pro's forum, and only Pro members that have been vetted by the AOPC may post advise, commentary or ask questions of the OP here. Please apply to the AOPC today, thank you.

    You can find the rules for posting and qualifications here.

    Further infractions may result in loss of posting privileges.
    Here's all the numbers (September bills aren't here yet):
    Electric - July - 2521 kWh - $231.23
    Electric - August - 2500 - 2500 kWh - $232.40
    Gas - July - 13.15 therms - $23.25
    Gas - August - 12.18 therms - $22.47

    Gas calc: ($23.25 - $22.47) / (13.15 - 12.18) = ($0.78) / (.97) = $0.80

    I can't do the electric calc because as you can see my August cost was higher but kWh was lower - this is because according to my billing statement the average cost per kWh went up slightly in August.

    Thoughts?
    Last edited by beenthere; 10-03-2012 at 04:47 PM. Reason: Removed quote of Non Pro * Member

  3. #16
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,311
    Homeowner314, this is the Ask Our Pro's forum, and only Pro members that have been vetted by the AOPC may post advise here. Please apply to the AOPC today, thank you.

    You can find the rules for posting and qualifications here.

    Your post has been deleted.
    Further infractions may result in loss of posting privileges.
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    How many times must one fix something before it is fixed?

  4. #17
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,323
    Quote Originally Posted by michael73 View Post
    Gas company = Vectren
    City = Carmel, Indiana
    Heat pump model = Bryant 264ANA (13.5 or 14 SEER and 9 HSPF)
    Furnace model = Bryant 355AAV (80,000 BTU)
    Full unit number for 264 ANA _ _ _ _
    Cooling Coil # __________________ ___________ ___ has not been provided.

    Heating Load at 2'F (~ Design Temperature) __________ " " _ " _ "
    Specific cost of gas (fuel, distribution) for the winter months for each month " _ " _ " _ "
    Vectren IN website is not as easy to deal with (so far) as some others in accessing the specific residential rate structure.
    -------------------\

    Can someone provide EXTENDED HEATING DATA in the PRODUCT SPECIFICATION (PDF file, ~30+ pages) for this BRYANT series?

    I am looking for the COP Heating in the 25' to 50'F range so that the economic and heating capacity balance points
    may be determined a little more accurately.
    I believe COP may be slightly higher than or close to:
    F _COP
    25 2.6
    30 2.8
    35 3.0
    40 3.1
    45 3.2
    47 3.3
    50 3.4

    However, using one's memory is surely not the best approach when getting down to the details.
    The realistic answer to the OPs question in post #1 is always - in the details.
    _
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  5. #18
    Join Date
    Jul 2008
    Location
    Rochester NY
    Posts
    4,739
    Hmmm.

    Possible broken assumption here - what efficiency is being assumed on the gas side?

    That efficiency has a LOT of dependencies...
    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.

  6. #19
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    Quote Originally Posted by tedkidd View Post
    Hmmm.

    Possible broken assumption here - what efficiency is being assumed on the gas side?

    That efficiency has a LOT of dependencies...
    Does actual measured effciency in the field vary that much from the rated AFUE??? I had always figured that sicne the heat exchangers had enough mass and surface area, that effciency was fairly consistent.

  7. #20
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,311
    Quote Originally Posted by motoguy128 View Post
    Does actual measured effciency in the field vary that much from the rated AFUE??? I had always figured that sicne the heat exchangers had enough mass and surface area, that effciency was fairly consistent.
    On some set ups it does.

    Of course, on many set ups heat pumps aren't getting their COP rating either.
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  8. #21
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
    Posts
    4,370
    I think the number of heat pumps not getting their COP is higher than the number of furnaces not getting their AFUE. Low airflow (which many systems suffer from) has a bigger impact on COP than AFUE.

  9. #22
    Join Date
    Jul 2008
    Location
    Rochester NY
    Posts
    4,739
    Choked airflow is just one commonly deficient dependency.

    What about cycle time? Low fire on that furnace is likely to satisfy quicker than low stage on the pump.

    How about comfort? Short cycling furnace could lead to temperature imbalance that causes crazy behaviors (thermostat fiddling, continuous fan, space heaters...), whereas long low stage output by the pump could balance the house.
    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.

  10. #23
    Join Date
    Jul 2008
    Location
    Rochester NY
    Posts
    4,739
    Quote Originally Posted by motoguy128 View Post
    Does actual measured effciency in the field vary that much from the rated AFUE??? I had always figured that sicne the heat exchangers had enough mass and surface area, that effciency was fairly consistent.
    My other combustion appliance efficiency is measured more transparently, thus more effectively. It's range is 25-46 mpg. That's a pretty big swing.

    Im finding you design this stuff so it gets and stays on the highway and surprising things happen to comfort and energy consumption. People who want their equipment to shut off, to NOT run, have it backwards.

    The only time I want my equipment off is when there is no load.
    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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