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  1. #27
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    Jan 2004
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    Lancaster PA
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    CPH is in the thermostat. It digital mimic of a heat anticipator. Set to 3. It will attempt to do 10 minute on, 10 minutes off. On Honeywell thermostats CPH is only accurate(maintained) at the equipments 50% load. Above or below that point it my do more or less cycles.

    On the GMH. If you set the stats CPH to 3 or 4, you won't get run times longer then 10 minutes, until its past the homes 60% heat loss mark. So it won't time into second stage, since it can be set to 12 minutes of first stage before it goes to second stage. Weather 3 or 4 CPH works better, is dependent on what the person/customer wants.
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  2. #28
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
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    11,357
    Quote Originally Posted by beenthere View Post
    CPH is in the thermostat. It digital mimic of a heat anticipator. Set to 3. It will attempt to do 10 minute on, 10 minutes off. On Honeywell thermostats CPH is only accurate(maintained) at the equipments 50% load. Above or below that point it my do more or less cycles.
    That's cool to know about the 50% being indicative of the system's run state. My Honeywell VisionPro was cycling the a/c this afternoon at 10 minutes on, 10 minutes off, and it was nearly 90 degrees outside. Meaning on a 90 degree day with my new cool roof, my home's heat gain is ~50% of what the system was originally sized for? Hmm....
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

  3. #29
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    68,308
    Quote Originally Posted by Shophound View Post
    That's cool to know about the 50% being indicative of the system's run state. My Honeywell VisionPro was cycling the a/c this afternoon at 10 minutes on, 10 minutes off, and it was nearly 90 degrees outside. Meaning on a 90 degree day with my new cool roof, my home's heat gain is ~50% of what the system was originally sized for? Hmm....
    With the amount of improvements you've made to home in the last few years. it wouldn't surprise me if you reduced it load that your system is over sized close to 50%.
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  4. #30
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
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    4,367
    Quote Originally Posted by beenthere View Post
    With the amount of improvements you've made to home in the last few years. it wouldn't surprise me if you reduced it load that your system is over sized close to 50%.
    That's why I always say install the smaller system then fix the house to get the temperatures where you want them. It's easier to put off fixing the house over high bills than if it's hot/cold inside.

  5. #31
    Join Date
    Jul 2008
    Location
    Rochester NY
    Posts
    4,739
    Quote Originally Posted by beenthere View Post
    CPH is in the thermostat. It digital mimic of a heat anticipator. Set to 3. It will attempt to do 10 minute on, 10 minutes off. On Honeywell thermostats CPH is only accurate(maintained) at the equipments 50% load. Above or below that point it my do more or less cycles.

    On the GMH. If you set the stats CPH to 3 or 4, you won't get run times longer then 10 minutes, until its past the homes 60% heat loss mark. So it won't time into second stage, since it can be set to 12 minutes of first stage before it goes to second stage. Weather 3 or 4 CPH works better, is dependent on what the person/customer wants.
    That might help them. Thanks!

    Quote Originally Posted by 54regcab View Post
    That's why I always say install the smaller system then fix the house to get the temperatures where you want them. It's easier to put off fixing the house over high bills than if it's hot/cold inside.
    I say the first part too.
    Gonna steal that second bit.
    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. #32
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
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    11,357
    Quote Originally Posted by 54regcab View Post
    That's why I always say install the smaller system then fix the house to get the temperatures where you want them. It's easier to put off fixing the house over high bills than if it's hot/cold inside.
    In my mind that would mean all planned house fixes should be known in advance, and calculated to deliver a figure for targeting the reduced capacity.

    Yes, I'm going at it back-azzwards. Interesting to note, however, is that the house fixes to date have not rendered the HVAC incapable of creating a comfortable environment, year round. It is oversized, but we're not cool but clammy in hot, humid weather, nor chilly and nostril-cracking dry in cold weather. Being it's not a comfort issue, it's an efficiency issue. At some point the HVAC will be redone to fit the envelope mods. In the meantime I look forward to next summer to log and observe the difference our new cool roof makes on the cooling load.
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

  7. #33
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,308
    Quote Originally Posted by 54regcab View Post
    That's why I always say install the smaller system then fix the house to get the temperatures where you want them. It's easier to put off fixing the house over high bills than if it's hot/cold inside.
    Would also be an easy way to get in a law suit. Can't force someone to make improvements to their home's envelope.
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  8. #34
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    68,308
    Quote Originally Posted by Shophound View Post
    In my mind that would mean all planned house fixes should be known in advance, and calculated to deliver a figure for targeting the reduced capacity.

    Yes, I'm going at it back-azzwards. Interesting to note, however, is that the house fixes to date have not rendered the HVAC incapable of creating a comfortable environment, year round. It is oversized, but we're not cool but clammy in hot, humid weather, nor chilly and nostril-cracking dry in cold weather. Being it's not a comfort issue, it's an efficiency issue. At some point the HVAC will be redone to fit the envelope mods. In the meantime I look forward to next summer to log and observe the difference our new cool roof makes on the cooling load.
    If the blower is slowed enough, it can keep the RH down.
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  9. #35
    Join Date
    Jul 2008
    Location
    Rochester NY
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    Quote Originally Posted by beenthere View Post
    Would also be an easy way to get in a law suit. Can't force someone to make improvements to their home's envelope.


    Truth of the matter is it won't unfold as being uncomfortable. In my experience "undersizing" IMPROVES comfort, balance, AND energy bills. But it sounds like a good way to orient a ho perspective.

    Sort of like the idea - no matter how many times I cut it, it's still to damn short.


    No matter how much I improve the home, my equipment is still exhibiting problems associated with oversized equipment. You can always cut it shorter, cutting it longer is a challenge.
    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. #36
    Join Date
    Oct 2012
    Posts
    16
    Actually there is a toggle switch on the board in my Goodman that lets me set it to run as 2-stage (high heat) all the time, no delays, no single stage only, so I could just run it that way. I don't believe there is any way to wire up this furnace to run with a two stage stat even if I wanted to.
    It does not have a variable fan, one speed only, unless you move the jumper on the board to a different 'speed'

  11. #37
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    Jan 2004
    Location
    Lancaster PA
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    Let it run as a 2 stage.
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