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the hell with that , any time i am uncomfortable the ac goes on . last thing i want to be is clammy and sticky because i don't want to run the ac below 90
The slower you you run the blower, the more moisture and less heat you remove from the air.
Not true if the inside and outside fans are run on a single shaft, as is moist common today. What you say is correct only if the condenser fan is always run at high speed while the evaporator fan (inside) can be run slowly. Running both fans slowly accomplishes nothing. Two fan motors cannot be exorbitantly costly, I wonder why most don't install them.
I guess they assume that most people believe any bullshyt they are spoon fed by manufacturers, as is becoming apparent in this thread.
read what i said , i said not on window units . you need a split system for a variable speed fan to work or separate condenser and evap motors. now variable compressors would be another story but they are not in window units yet .
i was just rebutting the statement that high speed is the most efficient , as long as you can use a variable speed fan it is not
read what i said , i said not on window units . you need a split system for a variable speed fan to work or separate condenser and evap motors. now variable compressors would be another story but they are not in window units yet .
Correct, not on window units, nor though the wall units.
Some manufacturer MUST make a packaged unit with two separate fan motors? The need is so apparent.
Aha, there IS a God:
But looking at the shape, there is no way that will fit my sleeve, it's 42 inches wide. Also, a bit pricey for 7700 BTU's (suitable only for keeping a bedroom cool and DRY.)
Of what conceivable use are variable speed compressors...besides doubling the cost that is.
Last edited by Kefir King; 05-07-2018 at 07:26 AM..
The ability to adjust power output to the compressor, rather than merely on-off functionality in traditional systems, allows users to achieve significant cost savings over the course of a year. In some cases these savings amount to 40% of the overall annual energy costs.
Variable speed technology enables this kind of efficiency for three main reasons:
Precise load matching
Less cycling on and off
Low amp gradual compressor motor startup
For example, if the temperature outside is 80 F and the thermostat setpoint is 72 F, the compressor only needs to overcome the 8 F delta to maintain optimal comfort for the homeowner. In these light-load conditions, the compressor may only need to run at 30% or 40% of full speed to maintain 72 F indoors. In traditional fixed-speed systems the compressors are either on 100% or off completely. In those situations, the system will cycle the compressor on and off as needed to match the setpoint as close as possible. This leads to power losses because the energy required to start up a non-variable speed compressor is much more than the energy required to gradually start a variable speed compressor and keep it running at 30% of full speed. This high efficiency operation during light-load conditions is the major efficiency advantage of variable speed technology.
I am not certain, but pretty sure that a compressor has an optimal efficiency when run at a certain speed, like most motors. If that is true, then running it at this or that OTHER speed makes no sense. Motors, even compressor motors really hate running slower than optimum.
I get the on-off cycling for motors is wasteful (how wasteful needs to be demonstrated)
but that is why it is important to properly size a heat pump, so the compressor is mostly balls ON.
Best way to destroy a motor, run it on a load that forces it to run more slowly than it was designed to.
MJ, let's call this one quits. I am sure we are boring the proletariat.
Last edited by Kefir King; 05-07-2018 at 08:04 AM..
it is really no different than a 2 stage system only far better and more flexible . in that case you have 2 compressors that interplay with each other . the problem is you can only have each off or on .
by having a compressor equal to the 2 but being able to have infinite range to match the load is a big energy saver . there is also a lot of energy saved on start up too with variable technology .
the ramp up can be nice and slow which avoids a 5 to 6x running amperage peak when starting each time .
you can have a nice controlled ramp up to speed instead of a draw of 5 to 6x running amperage and yet have full starting torque .
think of a gym which at times can be lightly loaded with a few people in the early morning while other times hundreds of sweating bodies create huge heat load .
don't forget many commercial places have demand meters plus kwh meters . these peaks are surcharged . so the lower the ramp up the lower the peak charges .
there are loads of reasons why variable speed compressors and fans are being seen more and more .
ya gotta brush up on the new technology kefir . the days of things being either on or off are going bye bye . now they can range in between being on and off when lightly loaded ....
Last edited by mathjak107; 05-07-2018 at 12:30 PM..
that is the techie nerd in me . i spent 40 years in an industry filled with technical crap . i now teach motor control and variable frequency drives one day a week in retirement so it never leaves me alone. but i enjoy it .
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