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  1. #1
    hugodrax Guest
    Just curious on what goes under the hood, these 2 speed compressors work both in 4 ton then 2 tons by using less pumps? but the motor still spins at the same time right?

    when they run at 1st speed does it consume less power or the same but just lower tonnage

    also when running a two speed does it kick in on high gear, cool down the home lets say from 85 to 74 then switch to the low speed mode just to maintain the house temp and occasionally kick back the high speed when temps creep up VS a single speed which would just cycle on and off.

    Anyhow between the speed capability of the indoor fan coil and the exterior compressor with 2 speeds it looks like a lot of calculations must go on I read that this infinty system measures the outside temp and inside temp to determine I guess comfortlevel etc..

    Also anyone know what is the filter size the 05 FE4 model uses(4 ton) I want to stick in a good 3m filter in it (Filtrete Ultra Allergen) this should be fine with the FE4 Handler correct. or will it mess with the system performance?

  2. #2

    Two speed compressor

    Generally when a two speed motor starts up, both winding are energized then falls back to the selected winding speed.

    for example Most compressors carry two winding the start winding and the run winding. At start up both winding are energized then the start winding is taken out of the circuit leaving the run winding in the circuit.

    At start up the amp draw is higher because both winding is drawing current. so more current is being used.

    this application applies generally to all multispeed motors.

    this happens with the 3 and 4 speed motors as well. Compressors and fan motors

    it starts at high speed then goes back to the selected speed.

  3. #3
    Join Date
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    There are more than one type of "2 speed" compressors. Since you are talking about Infinity I assume you are asking about the Carrier 2 speed Puron unit.

    This compressor only has one motor winding and does always run the same speed, however it does use less electricity on low speed. When it is running in low there is less load on the motor so it does not have to work as hard, thereby using less power. The motor in this compressor can turn in both directions. When it turns one way it only pumps on 1 piston (low stage), when it turns the other way it pumps on 2 pistons (hi stage). The direction it turns is controlled by the control board in the outdoor unit that responds to commands from the thermostat.

    Whether it runs in low or high depends on the call from the thermostat. The thermostat will make this decision based on how far the temperature in the space is from set point. When a proper load calculation is done, the system is sized to provide enough cooling or heating at the most extreme temperatures to maintain comfort in the space. Since most of the time it is not operating in these extreme conditions, the unit is usually oversized. With a 2 stage unit the unit can be better matched to the load at all conditions. If there is a larger demand for conditioning, the unit can run to the Hi capacity and when there is less demand it will run in Lo capacity.

    The Infinity does not use the outdoor temperature to decide on staging. It does have an option you can turn on that when the outdoor temperature gets above a certain point (you decide what that point is) that it will automatically run only Hi capacity.

    [Edited by plain spoken on 10-08-2004 at 01:52 PM]
    If all else fails....Try reading the directions!

    Tell it like it is and let the chips fall where they may.

    Any views or opinions stated here are strictly my own.


  4. #4
    Join Date
    Aug 2004
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    38
    Plain Spoken: I've got a follow up question regarding your explanation of the thermostat high/low call.

    Could you explain how the thermostat actually determines high or low speed?

    For example, let’s say the stat is set to 75 and the temp in the space climbs to 76, creating a call for cooling. In this scenario would a 1 or 2 degree temp differential (between the set temp and acual temp) cause the unit to always start in low speed and then move into second stage if the thermostat can't be satisfied in X amount of minutes?

    I'm also curious as to how the Infinity Fan coil operates. I.E. how the fan speed is determined by the thermostat. Is it the same principle as the heat pump?

  5. #5
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    Aug 2004
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    **Sorry double post**

  6. #6
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    How the thermostat works depends on the stat. There are a lot of different schemes of control used by various manufacturers. If you are asking about the Infinity, it is a calculated algorithum. It considers how far the temperature in the space is from set point, how long the unit has been running, or on a new call how long it has been off. It is not a fixed temperature, but changes with conditions. If you go over to the Infinity and change the setpoint, it resets all algorithums. At that point for the first call, .5 degree from setpoint brings on Lo.

    Control of the fan speed with Infinity? The Infinity "talks" directly to the variable speed motor. It always knows what the cfm and speed the motor is operating at and tells the motor what it wants it to be at. The exact cfm will vary depending on several variables. If the Infinity senses that the humidity in the space is too high, it can tell the motor to slow down some in order to dehumidify the air. If it senses that the humidity is just a little high and the temperature is further away from setpoint it will adjust the motor speed again in order to try and reach temperature and humidity setpoint at the same time. It can speed it up for electric heat if needed. These are just a few of the variable it considers. It knows the best speed for all the variable it may encounter and commands the motor to run accordingly.
    If all else fails....Try reading the directions!

    Tell it like it is and let the chips fall where they may.

    Any views or opinions stated here are strictly my own.


  7. #7
    Join Date
    Aug 2004
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    Thanks Plain. Yes I'm asking about the Infinity system (controls, etc.)

    How would the Infinity handle a temperature that is at set point, but high humidity. For example: Stat set to 75, space temp is 75, but humidity in the 60% range.

    In that situation with a call for dehumidification would the Infinity run at low speed compressor, low speed fan?

  8. #8
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    If dehumidification option is turned on, then yes as long as your humidity set point is below 60%.

    You select the humidity set point just like you select your temperature set point. You can turn dehumidification off or on, again a selection.

    The design of the Infinity is to provide much greater than normal dehumidification (as well as many other controls and comforts). It provides this dehumidification in seveal ways. 1. Any time you have a call for cooling (temperature above setpoint), the Infinity system operates at a lower cfm range to dehumidify. 2. If the humidity is above your set point during this call for cooling, it will slow the fan even further to do more dehumidification. 3. If you do not have a call for cooling and the humidity is above the set point, it will bring the cooling on with a very low fan speed just to dry out the air. In other words it becomes like a whole house dehumidifier. In this mode there are a couple of limits. It will only over cool the space up to 3 degrees. Once the space gets below 75 degrees then the 3 degree ovecool is proportionally decressed.

    If all else fails....Try reading the directions!

    Tell it like it is and let the chips fall where they may.

    Any views or opinions stated here are strictly my own.


  9. #9
    Join Date
    Oct 2004
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    47
    Originally posted by plain spoken
    If dehumidification option is turned on, then yes as long as your humidity set point is below 60%.

    You select the humidity set point just like you select your temperature set point. You can turn dehumidification off or on, again a selection.

    The design of the Infinity is to provide much greater than normal dehumidification (as well as many other controls and comforts). It provides this dehumidification in seveal ways. 1. Any time you have a call for cooling (temperature above setpoint), the Infinity system operates at a lower cfm range to dehumidify. 2. If the humidity is above your set point during this call for cooling, it will slow the fan even further to do more dehumidification. 3. If you do not have a call for cooling and the humidity is above the set point, it will bring the cooling on with a very low fan speed just to dry out the air. In other words it becomes like a whole house dehumidifier. In this mode there are a couple of limits. It will only over cool the space up to 3 degrees. Once the space gets below 75 degrees then the 3 degree ovecool is proportionally decressed.

    Plain,
    You seem to know a lot about this subject. I have had a new Amana Ultron system installed with a two speed compressor, a two stage furnace and a varible speed blower. The installer used a White-Rodgers thermostat model 1F95-391.
    This thermostat has all of the same control features you described about the Infinity. The thermostat has many points for connections but the installer only used five wires to hook up the system. My question is, is it possible to control a system with multiple speeds and stages (including humidity control) using only five wires. Thanks for any input.

  10. #10
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    North Richland Hills, Texas
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    Re: Two speed compressor

    Originally posted by mrcoolz4u
    Generally when a two speed motor starts up, both winding are energized then falls back to the selected winding speed.
    Actually, only the windings for the desired speed are energized. If you were to apply power to more than one of the speed taps in the motor, it would burn out the motor windings.

    for example Most compressors carry two winding the start winding and the run winding. At start up both winding are energized then the start winding is taken out of the circuit leaving the run winding in the circuit.
    I don't know of any compressors that drop the start winding out after startup. If it has a start kit, it will drop the start capacitor out, but the start winding will still be energized and have a run capacitor.
    There are some fan motors out there that drop the start winding out after startup, but they are rare. The last one I saw was about 5 years ago on a very old 7.5 ton Westinghouse condensor with a belt driven condensor fan. A centrifical switch dropped the start winding out after it got up to speed.

    At start up the amp draw is higher because both winding is drawing current. so more current is being used.

    this application applies generally to all multispeed motors.
    The amperage is higher at startup because the motor is pulling lock rotor amps. When induction motors start up, the amperage starts very high and goes down as it gets up to speed. It has nothing to do with how many windings are energized. Unless it is a part winding start motor, fairly rare, power is being applied to the same inputs when it is running as when it is starting...

    this happens with the 3 and 4 speed motors as well. Compressors and fan motors

    it starts at high speed then goes back to the selected speed.
    Again, power is applied to only one speed tap at a time or bad things happen. Some higher horsepower motors used in big applications have some interesting sequences of operation, but fractional horsepower motors are started on the same speed tap/winding they are run on.
    If more government is the answer, then it's a really stupid question.

  11. #11
    Join Date
    Aug 2004
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    Originally posted by hugodrax
    Just curious on what goes under the hood, these 2 speed compressors work both in 4 ton then 2 tons by using less pumps? but the motor still spins at the same time right?
    Different manufacturers do it different ways.

    plain spoken covered the Carrier Infinity way. Looks interesting, I have no experience with them though.

    Lennox used to do it with a compressor that had two speed motor with two complete sets of start windings and a run winding with two speed taps. The compressor spins in the same direction for both stages, just at different speeds. Gota love those 2 stage 9 pole contactors with mechanical and electrical interlocks! After years of working on them, I still change those contactors out wire for wire, one wire at a time, lol.
    Any units that used that Copeland 2 speed compressor worked that way.

    The newer 2 stage scroll compressors spin at the same speed for both stages, but the compressor is partially unloaded for the first stage. Copeland has a neet flash vidio explaining how it works on thier web site.

    Trane, ever the fan of the "bigger hammer" brute force method, just uses 2 different sized compressors.
    If more government is the answer, then it's a really stupid question.

  12. #12
    hugodrax Guest

    interesting

    Thanks for the update, I could imagine the computer must be pretty powerful to figure this stuff out. I could only imagine it would be an expensive service call when some component goes bad

  13. #13
    Join Date
    May 2004
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    Should not be any different than any other service call. The components are really the same in the units, the Infinity controller is not that much more than a Thermidistat. The cost is having someone who is not familiar with the system trying to figure it out on your time. As long as you stay with a trained service tech you should be ok.
    If all else fails....Try reading the directions!

    Tell it like it is and let the chips fall where they may.

    Any views or opinions stated here are strictly my own.


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