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  1. #1

    Question

    I have decided upon a heat pump system with a two-stage compressor. I live in southern Georgia and plan to live in the house forever. Most people tell me that the two-stage compressor will really improve the comfort level in the house. It also comes with the higher SEER unit which I want.

    My first Question is how does it improve the Comfort? In what way? I was told the VS air handler should help humidity control -- does the Two-stage system just help even more?

    My second Question is will the two stage compressor run a lot longer than a normal compressor? Seems if it runs at a lower capacity much of the time it will actually have to run longer than a normal compressor to heat/cool the house. I realize that running at lower capacity can reduce expense -- my fear is that after being accustomed to my old single speed compressor I will think that my new HP unit is running all the time. I actually enjoy the periods of the year that my system does not run much or at all.

    Can anyone help me understand the benefits or disadvantages of a two-stage compressor.

    Thanks in advance.

    J. D.

  2. #2
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,755
    It will run longer while in first stage, but it won't be using as much electric.

    The longer run time will help even the temp in all the rooms.

    Running longer, and with a humidity control, it should be able to control your humidity better.

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  3. #3

    Question Run Times

    Does anybody ever complain that the two-stage system just runs too long -- first stage or second? I guess it is because my system I am replacing is just so noisy that I am always glad when it shuts totally off. I have been promised that the AMANA Ultron 16 SEER Heat Pump I am getting will be very quiet. In fact, the salesman tells me not to worry about longer run times because I will barely hear it. But of course, I worry.

    How much longer run times (first stage or second) do these two-stage compressors run as compared to single stage? I mean are they running twice as long or 50% more or what can I expect.

    Thanks, J. D.

  4. #4
    Join Date
    Apr 2004
    Posts
    7,680
    Over the course of time the output from any system will have to be the same as the amount of cooling you need. Lets use an hour for kicks.

    Lets then assume you have a 2.5 ton system or 30,000 bthu capacity. What then if you have a mild day of say 90 and only have a cooling requirement of 20,000 btuhs. What happens now? Well the unit would run roghly 40 minutes out of the hour. That may be 10 on, 5 off, 4 times.

    A two stage unit would output closer to your actual need and reduce it's capacity to more closely match that of your needs. Many two stage systems run about 70 percent of full capacity on 1st stage. In this case you would have a 3 ton system (not many 1/2 ton increments in 2 stage systems). If your needs were the same as mentioned above the unit would put out a constant say 21,000 btuhs leaving you with little or no cycling.

    The energy is less for the lower capacity but is still using the same amout because of the longer run times, so what you get is better comfort for the same money.

    Now, many ultra high efficiency machines use 2 stages for a couple of reasons, 1st, thats one way to get the higher efficiency rating and 2nd, the ability to remove moisture is less, but longer run times allow that to be counterd. Now you still have more comfort for the same buck.

    VS motors can be configured to lower airflow, inclreasing moisture removal by lowering the coil temperature and decresing the sensible capcity. All these functions are targeted to help reduce operating costs AND improve comfort.

  5. #5
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,755
    I thinnk the amana uses the copeland scroll, so first stage is 70% capacity.

    So not quit as long.

    2 stage units are very quit in first stage, and I doubt you'll notice it nearly as much in second stage.



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  6. #6

    Beginning to understand

    I am beginning to understand. I live in the most humid place on earth seems like (Valdosta, GA). Everyone keeps telling me how the two-stage compressor will help with comfrom (humidity) control and how if humidity is less in summer I can actually keep the temp up several degrees and if will still feel cool.

    I am beginning to understand better.

    Does anybody know what type of Thermastat comes with the Amana Ultron Heat Pump? Can you set the humidity level you want in the house? Can you set the temp variance so that the unit only comes on if temp inside house rises 1 or 2 or X degrees above or below set temp. Does Amana offer different thermastat choices. Finally, what is the purpose of an outside thermastat?? -- was told if gets really cold outside could trigger the electric heat strips to help heat house (or something like this).

    I have learned so much about Heat Pumps in just a few days from this forum but obviously still have lots to learn.

    J. D.

  7. #7
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,755
    If they included the Honeywell th8321 thermostat it will do what you want.
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  8. #8
    Join Date
    Oct 2002
    Posts
    369
    The Ultron is very quiet...can't tell the compresor is running on low speed unless you put your ear on the unit...as to run time and staging....for much of the season you don't need the full capacity of cooling...like when its 80 degrees outside vs. 90 degrees outside....longer run time is not always a bad thing...its the starting and stopping that wears things out.
    Havin'a good time is what life is all about.

  9. #9
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Check into what Thermostat/Control you'll be getting,they may have one that increases dehumidification when the humidity in the home is above the set point.It may also be able to run a cycle to dehumidify even if there is no need for cooling,like in mild rainy weather.


    Not all Variable speed motors or control systems are the same ,even within the same brand,choose wisely.


  10. #10
    Join Date
    Jul 2004
    Posts
    253
    Hi,

    I live in St. Marys, GA and have a Bryant Evolution 2-speed compressor. On low-speed, you can't hear the system running in low-speed inside the house. You can, of course, hear the compressor outside the house.

    Originally posted by help in georgia
    I have decided upon a heat pump system with a two-stage compressor. I live in southern Georgia and plan to live in the house forever. Most people tell me that the two-stage compressor will really improve the comfort level in the house. It also comes with the higher SEER unit which I want.

    My first Question is how does it improve the Comfort? In what way? I was told the VS air handler should help humidity control -- does the Two-stage system just help even more?

    My second Question is will the two stage compressor run a lot longer than a normal compressor? Seems if it runs at a lower capacity much of the time it will actually have to run longer than a normal compressor to heat/cool the house. I realize that running at lower capacity can reduce expense -- my fear is that after being accustomed to my old single speed compressor I will think that my new HP unit is running all the time. I actually enjoy the periods of the year that my system does not run much or at all.

    Can anyone help me understand the benefits or disadvantages of a two-stage compressor.

    Thanks in advance.

    J. D.

  11. #11
    Join Date
    Apr 2003
    Location
    Eugene, Oregon
    Posts
    1,209
    Since I am not dissatisfied at all with the 10 SEER Goodman AC unit that I currently have (it has no variable speed air handler) I think the comfort of the Goodman 13 SEER with Variable speed air handler will be just fine. I see no need to pay the extra $2000 plus for the Trane XL16i or XL19i.

    Anyway, that is my decision as of now. Unless someone can warn me or give me better advice, I pull the trigger on this tomorrow morning.

    Sounds like a better choice, I am curious though how the change came about. As far as understanding the benefits didn't the salesman explain this in order to get you to change your mind on the system?
    Proud supporter of Springfield Millers and Oregon Ducks.

  12. #12
    Join Date
    Jul 2005
    Posts
    435
    The best decision I made was the Trane XL19i with VS airhandler. Since I live in S Fla on the seacoast, humidity control plays an important part. Yes the 1st stage runs a long time on those peek 90+ deg days but, since humidty is so low, I can raise the temp on the thermo and be very comfortable. I have saved $$ running this system. Even though the compressor runs a lot on 1st stage on those paek hot days, it does not cycle like other units, so you are saving $$, start current well exceeds run current.
    I can also say on those cooler days, it never runs continious in 1st stage because the smaller compressor can handle the temp. On the cooler days ( under 90+ deg) the 1st stage cycles without ever going into the larger second stage.
    The big difference, humidity is low as to keeping me from lowering the thermo. In fact members of my household sometimes sit in the chair in the evening with a blanket. This is with the thermo set at 79deg. It feels a lot cooler then 79, which most people are surprised when they find out!

    So I think that multiple stage condenser units tied to a VS airhandler is the only way to go!

  13. #13
    So, are you saying that a two-stage compressor removes more humidity that a single stage? I hadn't heard that before and don't see it listed as a selling point in any of the literature/websites.

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