HVAC 101

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Frequently asked questions about ductless mini-split A/C systems

What is a ductless mini-split system?

A ductless mini-split system is comprised of an indoor unit called the evaporator and an outdoor unit called the condensing unit. The evaporator is connected to the condensing unit by copper tubing and electrical wiring which is passed through a 2 ½” – 3” hole. Basically, it is a small central air unit with the flexibility of cooling or heating one room or more; zoning.

What is BTU?

BTU stands for "British Thermal Unit." It is a measurement of heat, and each individual unit represents the amount of heat required to raise 1 lb. of water 1 degree F. Each BTU is equivalent to roughly 252 calories of energy. Calculating BTU requirements is essential for minimizing your energy costs while providing you the optimal heating/cooling you need for your space.

How much BTU Do I need for my room?

PROPERLY SIZED CONDENSER AND INDOOR UNIT

Sizing is all about matching the house size to the HVAC system's size. A unit that is too big will be less effective and offer reduced air conditioner efficiency. Air conditioners remove both heat and humidity from the air. If the unit is too large, it will cool the room, before it has a chance to remove the humidity. The result will be a room that's not very comfortable to spend time in that cool moist air will make the room feel damp and clammy.

On the other hand, unit too small will be less effective as well. Air conditioner will be running all day to try to keep the room temperature cool while wasting energy.

The table below gives recommended air conditioning BTU's necessary to cool a single room. The data in the table assumes that the ceiling over the room is insulated and that the room is not over or is not itself a special heat-producing area such as a kitchen or boiler room.

Ductless splits cool a larger area at the same BTU level than do window air conditioners and portable air conditioners.

Below is an approximate sizing guide:

  • 250 square feet = 6000 BTU

  • 350 square feet = 9,000 BTU
  • 500 square feet = 12,000 BTU
  • 750 square feet = 18,000 BTU
  • 1000 square feet = 24,000 BTU
  • 1250 square feet = 30,000 BTU
  • 1500 square feet = 36,000 BTU
 
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How much does a split system cost?

The cost of the system depends on your space and requirements. You can fill our easy form for a service request and one of our professionals will contact you to better understand your needs and provide you with a price quote. To submit a service request form click here.

Is Ductless Mini-Split Air Conditioner a Good Choice?

The biggest advantage of mini-splits is that they require no ductwork, they are more efficient than other types of room air conditioners, they operate very quietly, because the outdoor condenser unit is separated from the indoor evaporator unit, and they normally come with remote control capability.

Split systems are cheaper and easier to install than central systems, while they can also offer multiple zones cooling; 2 to 4 cooling units can be connected to one outdoor condenser unit and each indoor unit can be used independently.

Call now for advice on how to choose a ductless mini split A/C system 516-328-3838

References:

Mitsubitshi - What size system

Energy star - Air Condition Room

Michael Zhong