chiller capacity calculation

Simple answer, Approximately 500 sq ft / ton residential and 600 sq ft / ton commercial. This is just a guide line depending on the heat transfer efficency of the materials used in construction.

Now if you really want to learn how to calculate heat load I suggest you take an Air conditioning engineering course on heat load calculations.

If you just want a fairly accurate number then search for a program on the net that does this. "Heat load calculation" here is one - http://www.hvac-software.com/hvac/tofc2.asp

Figuring heat loads involve different areas such as heat transfer, conduction, convection, radiation, the moisture content of the air, sun exposure North, South, East, West, geographical location on Earth, any special weather considerations, building material composition and heat rate loss through these items, Infiltration of air through cracks in construction, human loads including heat and moisture dissipation, outside air loads through ventilation and door window openings, internal equipment loads cooking, lighting, computers, heat producing electrical equipment etc etc.

Now if you are after human comfort then remember most of the heat load calculation programs were designed for a northern climate, you must factor in humidity content and try to maintain around 50 - 60 % relative humidity and around 75 - 78 Deg F. This means you may have to use a de-humidifier in moist climates when the temperature outside is lower than your set temperature, and you may need a humidifier in drier climates to maintain human comfort.

Hope this helps.

Paul

Is this DX system or Chill Water.

The Heat load is figured the same regardless of equipment used. DX does a %10 better job removing heat/humidity because of colder evaporator coil. The guide line I gave is mainly used for bidding purposes. You must understand the differences in construction materials used to figure the accurate heat load or it can cause one of two problems. The equipment is undersized and will not cool properly on a hot day and will run longer producing very dry conditions (bad for sinuses) with higher electrical bills. Very Costly! The second thing that may happened is the equipment is over sized, (larger electrical bills), which may cause the unit to satisfy the temperature quickly but the humidity is not removed so the thermostat will be lowered to remove the humidity thus causing the unit to run longer and use more electrical costs. Also the geographical location of the building makes a huge difference in heat/humidity gains as well as the type, size and R factor of the insulation used.

400/500 sq ft / ton is based on standard building practices with 90 deg outside air temperature and codes in the Southern States.

If your location is in nice cool dry Maine the guideline may be 600/700 sq ft / ton.

paul