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  1. #1
    Join Date
    Mar 2008
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    205

    BeenThere, this comment of yours caught my eye

    "Long run cycles prolong the life of the compressor of an A/C system."

    This is what we do in the summer. Pull the T-stat way up to around 80-82* then around 5 or 6 PM, pull her down to sleepin' temperature (70*)

    Now if I'm readin' your post right, this is much easier on said compressor (and bank account) than leaving it on 70-72* the entire day?
    Last edited by RomulanSpy; 07-06-2008 at 03:56 PM. Reason: mispelling

  2. #2
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    68,171
    Somewhat depends.
    If at 80 and 82 it cycles a lot, then your not getting long run times all the time.

    Then leaving it set at 70 or 72 is easier on the compressor, because more of the cycles are longer run times.

    Short cycling takes out more compressors. And usually, those compressors are on systems that are over sized. And short cycling even when its 80 to 85 outside, let alone when its 75.
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  3. #3
    Join Date
    Mar 2008
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    205

    It hardly comes on at all

    at 80-82*

  4. #4
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    Short compessor cycle is possible at high set back temps.
    Not saying it is happening with yours.

    I set mine back too on mild days. Hardly runs during the day while I'm at work then.

    Short cycling while at normal stat set temp is what I was mainly refering to.
    Just gave you an FYI so you could be aware.
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  5. #5
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,470
    T-stat day time set-up is big energy saver. That's going tobe my strategy if the outside temperature ever warms up enough to activate my a/c.
    Unfortunately, most of these a/c experts recommend sizing the a/c to the minimum. I like enough cooling capacity to handle the hotest days, extra company, and being able to cool down from tstat set-up in a couple hours. The fear is that the extra .5 ton of capacity will make the a/c unable to control humidity during low/no load cooling conditions. We are hearing from many about not being able to maintain reasonable temps as the systems age or even when brand new. The reality is that an undersized a/c is unable to control the humidity in home with adequate fresh infiltration and occupants during low/no cooling load conditions. This year, many homes with basements have little cooling load have low/cooling load while having significant latent moisture loads. An adequately sized efficient, dehumidifier is an excellent part of ideal comfort, energy savings, and indoor air quality package. I just replace a 25 year old a/c that only operated when the home was occupied. The a/c had its original components and was operational. How many minutes shorter is a a/c system with an extra .5 ton of capacity? How much less moisture is removed by that shorten run time? Will the .5 ton smaller system dehumidiy my home during cool wet weather? Regards TB
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

  6. #6
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    Some people promote over sizing to sell whole house dehumidifiers.


    Your sig says keep our home at 45&#37;RH.
    But by the charts you posted, you don't maitain a steady 45% humidity.
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  7. #7
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
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    Fresh air when the home is occupied is valued by all who have knowledge of indoor air quality. In green grass climates, the latent cooling load exceeds the sensible cooling the majority of the hours. If you value purging indoor pollutants, renewing oxygen, controlling indoor humidity to avoid mold/dust mites, comfort, and energy efficiency , the whole house dehumidifier is ideal.

    Some don't want dehumidifiers, so they can sell full featured a/cs that are high priced, difficult to install correctly/set-up/trouble shoot and unable to control humidity during wet cool weather. It's ok with me. The market will sort out the ideal systems. I have the data to prove the a/c is unable to maintain <50%RH with adequate fresh air during low/no cooling loads. As a/c mfgrs. one by one offer the dehumidifier option your opinion may change. Do not let "beenthere" became "staythere". Regards TB
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

  8. #8
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,171
    I don't sell 2 stage as cure all for humidity and IAQ problems. No one product can do that.
    Like you tend to claim.

    I can give you plenty of places to go and talk to them all about IAQ and whole house dehimidifiers.
    And then you can explain why they need it now. Even though they haven't needed one for 30 or 40 years.
    You can show them all your charts, and quote ASHRAE all you want. You might sell 1 out of 100 sales calls if your lucky. In this area.

    Your size for the once or twice a year 20 to 30 person party, or those 2 to 3 times it reaches 100&#176; once every 4 or 5 years is propaganda to sell your product.

    You quote ASHRAE for IAQ. But no where does ASHRAE say to size for the conditions you recommend to size to.

    Selective quoting to benefit your sales.
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  9. #9
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
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    18,836
    Quote Originally Posted by teddy bear View Post
    Fresh air when the home is occupied is valued by all who have knowledge of indoor air quality. In green grass climates, the latent cooling load exceeds the sensible cooling the majority of the hours. If you value purging indoor pollutants, renewing oxygen, controlling indoor humidity to avoid mold/dust mites, comfort, and energy efficiency , the whole house dehumidifier is ideal.

    Some don't want dehumidifiers, so they can sell full featured a/cs that are high priced, difficult to install correctly/set-up/trouble shoot and unable to control humidity during wet cool weather. It's ok with me. The market will sort out the ideal systems. I have the data to prove the a/c is unable to maintain <50%RH with adequate fresh air during low/no cooling loads. As a/c mfgrs. one by one offer the dehumidifier option your opinion may change. Do not let "beenthere" became "staythere". Regards TB
    Over priced dehumidifiers,sold as bandaids by those unable of finding the real issue(s).

    The above statement is more true then your claims about top of the line systems.


    Rained several inches today and a lot yesterday,set poit 76,it is 76,RH =50,same as it's set point.

    ERV and nook window cracked all day,with kitchen exhaust on,due to smokers in the house.

  10. #10
    Join Date
    Jul 2008
    Posts
    19
    What constitutes short cycling? I haven't timed my cycles (yet) but for the most part it seems to run for ten minutes shut off for five and start again. However, during the peak of the day it runs much longer.

  11. #11
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    A 10 minute on 5 minute off cycle is ok.
    A 5 minute on 10 minute off is questionable.
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  12. #12
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
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    11,350
    Quote Originally Posted by teddy bear View Post
    Fresh air when the home is occupied is valued by all who have knowledge of indoor air quality. In green grass climates, the latent cooling load exceeds the sensible cooling the majority of the hours. If you value purging indoor pollutants, renewing oxygen, controlling indoor humidity to avoid mold/dust mites, comfort, and energy efficiency , the whole house dehumidifier is ideal.

    Some don't want dehumidifiers, so they can sell full featured a/cs that are high priced, difficult to install correctly/set-up/trouble shoot and unable to control humidity during wet cool weather. It's ok with me. The market will sort out the ideal systems. I have the data to prove the a/c is unable to maintain <50%RH with adequate fresh air during low/no cooling loads. As a/c mfgrs. one by one offer the dehumidifier option your opinion may change. Do not let "beenthere" became "staythere". Regards TB
    Perhaps if you ever get some hot, humid weather, you might understand how many of this who live in these conditions for a large part of the year tend to look a bit puzzled when reading a repeated mantra of "low/no cooling loads during cool, wet weather". This is not my reality except for a few weeks a year. Right now we are in a moderate drought. Last year we had a tropical low stall over us for the entire month of June, dumping tons of rain. It made for warm, wet weather...i.e. HUMID.

    I also have no basement. My house is not airtight, but a bit better than average for a 49 year old house due to efforts I have taken to improve tightness. Controlling humidity is not a problem. Between natural air infiltration, ingress/egress patterns, and opening a bathroom window while that room is occupied, and ventilating the bath with a desk fan, I still don't have a humidity problem.

    On the 4th of July we had a party at the house. People going in and out to and from the patio to use the outdoor grill and socialize on the patio. Food cooking inside. 95 degrees outside. I turned the stat down a notch in anticipation of the higher heat load, just like I do at work when a large crowd is expected in the auditorium. My system did fine; nobody was fanning themselves in discomfort.

    Now, a question for you...one of your posts above seems to suggest an underskilled labor pool for installing higher grade residential HVAC systems, leading to complications regarding performance from these systems. Now, is the labor pool substantially more skilled for the installation of whole house dehumidifiers?

    Any aspect of "staythere" from my perspective is that reducing whole house INFILTRATION and controlling fresh air introduction into a home through climate controlled means can, for many of us, supplant the need for a separate means of dehumidification - that is, apart from a/c.

  13. #13
    Join Date
    Aug 2003
    Posts
    466
    Quote Originally Posted by beenthere View Post
    A 10 minute on 5 minute off cycle is ok.
    A 5 minute on 10 minute off is questionable.
    Many higher efficiency systems today take at least 15 minutes to even reach their full efficiciency. This is why we need to wait so long in between temperature/pressure checks. I prefer the on cycle of systems to be much longer, which means I prefer exact or even undersized capacity systems. Every system is basically oversized to any temperature below the design temperature, so we need to be diligent to not overshoot capacity to design temperature.

    The very worst thing we can do to any motor is to start it. This is indicated in the high amp draw of a motor on start up. It takes a lot more effort to start a motor then it does to run one, so compressors, outdoor fan and indoor blower motors all last longer and operate more efficiently when they opererate for longer cycles with less cycles per day.

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