One of the new systems being promoted these days is known as a dual stage comfort system. It truly is the luxury car of home comfort systems. How this system differs from others is the fact it is two air conditioning systems in one. How this works is the outside unit has two compressors. What that means to you is increased comfort level by providing exaggerated dehumidification and more flexibility in comfort performance. As mentioned, the system has two different compressors, one of the compressors has a 70% capacity of rated size, the other has 100% capacity of rated size. They never run at the same time. In plain language this means that if we have a system that is designed to remove 36,000 btu’s and the system is running in the 70% mode, we have a removal capacity of 24,200 btu’s. And if running in the 100% mode you will get 36,000 btu capacity. The next question that usually pops up is “why in the world would you want your system to run at anything but 100% all the time”. Remember that an air conditioning system has two major functions; it removes heat but also removes humidity. This is achieved through air exchanges, this is the number of times per hour all the air in your home goes through the system. Each time the air passes through, it is cooled and dehumidified a little more. If there isn’t that much heat, such as in the morning, but the humidity has built up over night a regular system running at 100% will not give the system the opportunity to achieve enough air exchanges and the temperature may be where it is supposed to be but the humidity could still be high. So what do you do, you go and turn the temperature down a little more. There also is a energy cost saving of running your system at 70% vs. 100%. Not to mention it is quieter. So how often on average does it run at 70% of the rated speed. The answer may surprise you. The system runs in the 70% mode on average 70-80% of the time, with the 100% mode only running the balance of the time.
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