Load Capacity for Air Conditioning

It depends ..............

Is it a kitchen, an electrical MCC, a computer room, a washroom, ..............?

Does the room have any outside walls or windows?

Where are you located?

kichanroom with electrical mcc 108 kw two windows

Hello "Guest",

Apart from above, add to the list of details needed are:

1. Location
2. Elevation above mean sea level
3. Relative Humidity required in air-conditioned room
4. Temperature required in air-conditioned room
5. Relative Humidity external to air-conditioned room - Give monthly averages table please
6. Temperature external to air-conditioned room - Give monthly averages table please
7. Other details as necessary to give you a proper answer.

Reply here, with

In addition to data mentioned by Mr.Spark station you need to furnish windows in all four walls with Glass properties like u value solar heat gain window rating,Number of people expected to occupy the conditioned space.lighting and equipment loads like computer.UPS,printers,fax machine etc there are number of websites providing on line heat load calculations please search using google search engine air conditioning calculations cant be done using Thumb rules.i wouldn't recommend

regards

crm

Absolutely zero! (Sorry, I couldn't resist). Since the volume of the room is 20 ft x 20 ft x 0 ft = 0 ft³, there is nothing to cool.

Now that I've got that out of my system, please provide a few more details and we'll try to help.

I also faced similar problem of calculating the airconditioning capacity for our server room and could resolve using certain formula which calculate tonnage using the amount of heat that is generated by an equip by converting its electrical wattage into heat output but I wish to know given the room temperature plus the heat generated by the equipment how to calculate the tonnage required for maintaining 18 degree centigrade in areas where the room temperature ranges between 25 and 35 degrees centigrade.

heat output of the server alone will not help you need to know Humidity to be maintained in side the server room at 18Degree C at NTP conditions you would kill the server with condensed moisture my friend.un less you know humidity of ambient air outside the sever room please check form your local met-department ambient temperature wet and dry bulb temperatures during summer,winter and monsoon and if you are located in a coastal area its all the more important to check these parameters to size your chiller correctly to save your server and energy demand of your building.

crm

hello CRM as you are in Bangalore why dont you give me you phone number I call you and discuss with you or may be you visit our office my number 25119332 sorry no mobile.

Ok unless you have never visited CR4 before you deserve what you get for nor giving enough data. But here is a place to start.

Lets assume a couple of this and then you can figure out what you need.

20'X20'X8' in an area of the world with minimal humidity and good insulation will require a 1.5 ton unit.

dear mikethea/cguy what you have said is ok, but you haven't told how to calculate the tonnage required for cooling to 18 degree for a given atmospheric/ambient temperature for example my town's summer temperature is 37 degree centigrade max, now to achieve the difference of 16 degrees how do I calculate the tonnage?

Down and dirty desert style.

20X20X8 = 400 / 450 (btu per cubic foot) = .88 ton.

30% increase for poor insulation equals 1.1 ton

20% increase for area and weather unknown conditions equals 1.37 ton

Nearest size that I can purchase is 1.5 ton. Short cycles should be very few.

boss, you haven't still answered my question. you have missed out the temperature difference factor.

Sorry my friend I am a lay problem solver and I did not connect the first input and the server room as the same problem. I dont have enough data to conclude an exact answer but you are correct I have not given what you need.

Sorry

More data and I will work it out for you.

Mike

You need to know the volume of the conditioned space. What's the ceiling height?

You will be dealing with both latent heat and sensible heat. A reduction in sensible heat is represented by a reduction in the dry bulb temperature; latent heat is the heat which will be released when moisture (humidity) is condensed out of the air which is being cooled by your equipment. Both must be taken into account. If you live in a humid region, like the Gulf Coast, your cooling capacity must be greater; in a dry area, it will be less.

Heat load (or cooling load) depends on outside air temperature and humidity, exposure to solar radiation, and infiltration, and the ability of your walls, doors, windows, and ceilings to resist the transfer of heat by all these pathways.

Both latent and sensible heat may also be produced by things inside the conditioned space, such as cooking stoves, electronics, motors, and human bodies.

A seat-of-the-pants estimate for residential installations is one ton (12,000 BTU) for every 400 square feet of floor space, assuming a seven foot ceiling. Your requirement may vary considerably from that, but you will at least know if your air conditioning salesman's estimate is in the right neighborhood.

A course in heat load calculations is beyond the scope of this forum, but here's a site you may find helpful: http://www.engineeringtoolbox.com/latent-sensible-cooling-load-d_245.html

If you'd like to go further, the Carrier Corporation has published excellent training and educational materials for many years. http://www.carrieruniversity.com/

Good luck!

Gee..! Let's see probably by some estimation assuming these factors exist and taking in account all CR-4 pointed out before by the Buddy's here you may give a shot and see how work out. This is just a little quick formula to help out but you may take any other factors in consideration just in case. Double check anyhow.

A. Number of peoples occupying area___X 900=______Btu's.

B. a)Roof Squares Feet's punish by Sun___X15=____Btu's.

b)Ceiling Square Feet's lower plant___X5=_____Btu's.

C. Walls

a)Punished by Sun (linear feet's)____X90=____Btu's.

b)Other walls (linear feet's)____X30=_____Btu's.

D. Windows

a) Windows Punish by Sun (Square Feet's)

1. Locate South____X60=____Btu's.

2. Locate East____X110=____Btu's.

3. Locate West____X110=____Btu's.

4. Other Windows____X17=____Btu's.

E. Electric Equipments

a) Watts____X3.4=____Btu's.

Total Capacity in Btu's per hour_____.

Allset buddy check it out but with all the help here at CR-4 pal's you'll be on your way for a nice installation. Great post all absolutly.

Btu's Juice,

MC

Thanks a lot for the info. But I am hungry for more info. I wish to know how to arrive at the tonnage to maintain certain temperature. For example from 30degreeC to 18degreeC. I have observed most of the calculation sites talk about the tonnage and not about maintaining what temperature.

answer to your question depends on water flow rates selected in gpm and Inlet and out let temperature in other words delta T across the chiller and not forgetting condenser inlet and outlet temperatures.and delta T across the condenser you can contact your chiller supplier who would should be able to advice you as chiller manufacturer sizes the equipment.

crm

Hi,

Two suggestions;

1, For Server room most of the heat is generated inside the space by the server itself and the heat leakage from outside to the space shall be very minimum. So the unit capacity is independed of the inside set temp. ofcource the cooling coil selection should be proper.

2,For kitchens the heat dissipated from the kitchen equipments and the make air required for the kitchen exhaust system (if conditioned make up air is required) are critical for unit sizing.

In general for kitchens and server rooms thump rules shall not work due variations in requirement are very broad. only a professional HVAC design engineer can do a satisfactory estmation.