AHU Sizing AHU configurationOur AHU sizing guide enables you to rapidly select the appropriate unit size for a specific project requirement.  Simply, select the velocity and volume (or next highest value) required from the table. Then, locate the unit size, external width and external height from the left hand column. Finally, add the base height to the external unit height and 50mm for a pitched roof if the unit will be sited in an external location. Please note that dimensional restrictions may dictate a higher velocity of around 3m³/s. This, however, is likely to mean that the AHU specific fan power will exceed Building Regulations requirements. Subject to external static pressure and internal components, Building Regulations requirements may be met at an AHU velocity of 2m³/s.If the image doesn't display correctly or you wish to download the guide as a PDF please use the link below:AHU sizing guide (matrix below as a .pdf file) Approximate Length of Air Handling Unit Components for Unit Size (.pdf)Approximate Weight of Air Handling Unit Components for Unit Size (.pdf)

Contact our AHU sales engineers for further assistancegas furnace ac unit AHU Unit Design Enquiry Formair conditioning units high efficiency Contact a Barkell Account Managertypes of portable ac units Download a product guideCooling a business office can be expensive, but improved employee comfort can improve performance and production, which makes the extra investment worth it. However, the biggest concern when looking to purchase an air conditioning unit or to upgrade a current unit includes determining what size unit best fits the workspace. If the unit is not big enough, then it will not adequately cool off the office. Purchase too big of a unit, and the air flow might become restricted if the ductwork is inadequate.

Before buying or replacing an air conditioning unit, shoppers should educate themselves on the different air conditioning unit types, including single and multi-stage units, the different sizes, and the number of BTUs or tons that they need to cool an office space. They should also determine which design best fits their needs, such as a rooftop unit, a cooling tower, or another type of air conditioning unit. When purchasing an air conditioning unit, shoppers must decide whether they need a single or multi-stage unit. Both types are described in the table below. Most often used in home environments or at hotels but can be found in smaller businesses; single-stage refers to the fact that the unit only has one setting, "on" Offer users the ability to operate the system at different outputs, for example 60 or 100 percent, for different levels of cooling; more efficient than single-stage; For most offices, especially larger ones, multi-stage units give office managers and business owners the option of setting the output of the unit depending on the time of day or year.

So, an air conditioning unit can be set for 60 percent of its normal output for the fall months, but when summer rolls around, users can set it a little higher. The first step in purchasing an air conditioning unit for a business is determining how many BTUs are needed. This measurement describes the size of the unit or units in tons. The sections below detail how to calculate BTUs and tons. The size of the unit makes a big difference when determining how much output, in BTUs, it has. A BTU, or British Thermal Unit, is the amount of heat needed to heat 1 pound of water one degree Fahrenheit. Though BTUs are important, most larger air conditioning units are rated in tons. Since 12,000 BTUs equal 1 ton, an air conditioning unit rated at 3 tons can produce 36,000 BTUs. A lot of calculations go into figuring out how much it would take to cool a building. The section below contains the steps necessary to determine how many BTUs are necessary to cool a building. Calculate the square footage of the area to be cooled.

If the business is divided up into zones that will be cooled by separate air conditioning units, then keep these measurements separate. Multiply the square footage obtained for each area by 25. Add 400 for each person who works in that particular area. For each window, add 1,000. The number gained from steps 1 to 4 represent the minimum BTUs that the air conditioning unit should provide. The calculations above are for rooms with an 8-foot ceiling. Higher ceilings require a higher number of BTUs to adequately cool the area. While calculating BTUs is not rocket science, converting those calculations to tons might be a little more involved, since most large rooftop units are sold in tons. Assuming a minimum amount of doors and windows in an area, the chart below gives some base BTUs and their ton equivalents for office managers to consider when purchasing an air conditioning unit or units for a business. There are other factors to take into account when calculating BTUs, such as the number of windows and doors, as well as the number of people sharing the office space.

Keep all of these factors in mind when calculating BTUs and tons. Another consideration when buying an air conditioning unit is its location in the business. This could be on top of, beside, behind, or within the building itself. The table below lists some of the common types of airconditioning units and their locations. In larger buildings, the condenser unit, which helps dissipate the heat, sits atop the building; this type of system does not work very well when cooling a multi-story building In a split system, heat is shunted away from the building through a coil system; the coil system on the inside is cooled through the use of a gas, such as freon; the cold air is distributed through ducts Air handlers deliver cooled air to different parts of a building; this allows for the cooling duties to be split up, reducing the workload on a single air conditioning unit When buying or replacing an air conditioning unit, determine where the new unit must be placed. If it is to be placed in the same location as the old unit, choose the same type of unit as the old one.

Otherwise, inspect the area for sturdiness, such as on top of a building, and then make adjustments as necessary, such as pouring a concrete pad beside or behind the building to hold the unit. When purchasing an air conditioning unit to cool a business, shoppers can select one large unit to cool the whole area or choose smaller units to cool specific areas instead. The number of units used primarily depends on the size and configuration of the building. Smaller buildings can get away with using a single large unit. In bigger buildings with many rooms, smaller units might be a better choice. Each of the smaller units attach to a specific air handler that delivers the cool air to a particular part, or zone, of the overall building. That way, the load of cooling the structure is split up. For those who do not want to use one of the above unit types, there are a few more alternatives to choose from. The following table contains two other options to consider when purchasing an air conditioning unit for a business.

AC unit is installed on the roof or behind the business; cools water to 40 to 45 degrees fahrenheit; cooled water piped through a building and fed to air handlers; for cooling large, multi-level structures A cooling tower creates a stream of cold water running through a heat exchanger; the water cools the hot coils; air is blown through a stream of water causing some to evaporate, which cools the water stream When choosing an air conditioning unit for a business, consider all options. For those unsure of the best option, consult an air conditioning or HVAC specialist. To buy an air conditioning unit or parts online, visit the eBay marketplace for a variety of product options. To find just the right product, first do a search by entering keywords into the Search box on any eBay page. Use terms like "5 ton central air conditioning unit" or "Trane air conditioning unit," for example. After viewing the search results, narrow the list down even further by clicking on the category filters to display only the listings that are in the HVAC or air conditioning departments, for example.

Also read over eBay's Search Tips page for more advice on searching for air conditioning units with keywords. And, also check out specific sellers' eBay Stores for more business product options. Shopping on eBay is quick, easy, and secure. When looking through applicable product listings, search for key details like product cost, item quality, sizes, and colors. If any other questions remain after reading through the listing, contact the seller by clicking the Ask a Question link on the seller's listing page. And before going through with a purchase, check the seller's feedback rating to make sure you are happy with his or her past sales performance as rated by other shoppers. Buying the right air conditioning unit for a business is an important decision. Shoppers do not want to purchase a unit that is either too small or too big for the building that they occupy. When cooling a large area, shoppers do have some options, from including single and multi-stage units, among others.