Indiana » Save Energy & Money » Calculate Your Home Energy Savings » Room A/C CalculatorSizing Estimator for Air Conditioners Desired Indoor Cooling Temperature (°F) : The cooling capacity of an air conditioner is measured in tons. In regards to cooling, 1 ton is equal to 12,000 BTU's (British Thermal Units). A standard air conditioner ranges in size, from smallest to largest: 18 = 1.5 Ton (18,000 BTU) 24 = 2.0 Ton (24,000 BTU) 30 = 2.5 Ton (30,000 BTU) 36 = 3.0 Ton (36,000 BTU) 42 = 3.5 Ton (42,000 BTU) 48 = 4.0 Ton (48,000 BTU) 60 = 5.0 Ton (60,000 BTU) For example, a model SSX160241 is a 2 Ton (24,000 BTU) air conditioner. There is only one correctly sized air conditioner or heat pump for your home. A unit that is oversized will turn on and off too frequently, called “short cycling.” Short cycling causes the unit to lose both efficiency and the ability to properly dehumidify the home. This may result in higher utility bills and a less comfortable home.

A unit that is undersized will run too often, and on the hottest days of the year, may not be able to adequately cool the home.The thermal gain of your boat varies greatly during every 24 hour period, and peaks when the sun is at its maximum strength. You must at least equal this otherwise the temperature inside your boat will go up rather than down when you close it up and turn on the a/c at noon. If you undersize your load you will be very uncomfortable and unhappy with your system when you need it the most! Significantly oversizing the system will result in system "short cycling" - not giving the system adequate run time to satisfactorily dehumidify the vessel. The general rule of thumb for sizing a pleasure boat is using the formula of 14BTU's/cubic foot (480 BTUs/cubic meter) of air conditioned space. This factor is for typically constructed pleasure boats and should be adjusted if non-standard construction techniques have been

It is prudent to use a factor of 16 to 19 BTU's/cubic foot (550-650 BTUs/ cubic meter) for areas that are used during the heat of the day that have a lot of sunlight coming in - for example a pilothouse, especially if the roof is not shaded or well insulated. For areas below deck that are primarily used after sunset such as a stateroom, you can usually drop this factor to 10 - 12 BTU's/cubic foot(380-410 If you plan to air condition the vessel only in the evening hours, or if your boat is under a canopy and out of the sun, you can typically use a factor of 10-12 BTUs for the entire vessel. In many installations we have designed systems that will cool the main salon during the day and the entire boat, including the staterooms, in the evening by using multiple ducting with closeable grills combined with a more powerful blower motor. This frequently results in a single system accomplishing what you would

typically need two systems for, saving you a lot of money and frequently eliminating the need for an additional shore power service. about 10 BTUs/cubic foot after sunset, therefore if entire capacity of a single unit to the main salon only, during the day, you will end up with, for example, 18 BTUs/cubic foot in this smaller area during daylight hours, andold singer ac dc 10 BTUs/cubic foot during the evening when you openhow to size window ac units up all of the ducts and cool the entire boat).how much is it to replace an ac unit Exceptions: Catamarans and boats with large "greenhouse" like glass that allows lots of direct sunlight into the boat: Unless you can shade these areas so they are not in the direct sunlight, add

about 600 BTUs of a/c capacity for every square foot of this glass (not the vertical panes as well). Tinting the glass helps a lot, however a simple tarp a few feet above the glass is the best solution while not eliminating your view. fabric the better for dark colors also block most of the UV radiation unlike a white fabric. that tinted glass is not permitted in the navigation station because it almost eliminates your nighttime In applications where there is an unusually high heat load from many passengers such as a party boat, you should also increase yourThe general rule of thumb is 250 BTU's for inactive occupants and 500 BTU's for active occupants such as working or dancing. Please note that these formulas are for maintaining the desired temperatures of a typical vessel. Don't arrive at your boat at noon after it's been baking in the hot sun for hours with an inside temperature of 120�F, and expect it to be at 72�F in

You usually have thousands of pounds of furniture, fiberglass and steel that needs to be dropped 50� before the a/c has to only maintain this temperature. Just as in a house that has been closed for vacation, it may take several hours for the a/c system to catch up. "Thermal Load" or "Thermal Mass" is most easily overcome during the evening hours when the thermal gain from the sun is nonexistent. program the system to go on a 3AM, for example, in these situations - especially with commercial boats, unless you want to grossly oversize the system to Using these factors combined with some common sense will almost always produce a satisfactory system, however you can always hire a professional to prepare a thermodynamic heat load analysis for your particular vessel. We have a lot of experience sizing different vessels and will work with you in Equally important to properly sizing the vessel is determining how much individual