Control Room Air Conditioning

Ordinary split units generally recirculate the air within the conditioned space and do not draw additional air from outside the conditioned space. Ergo, no increase in pressure. A central unit can draw air from an external source, pumping in more air than it is pulling out to recirculate. Thus, you can have positive pressure in the space.

In split a.c mostly return is circulated with out adding much fresh air for ventilation . Infiltrated air through door and other leakages act as source of fresh air for ventilation. In central plant you have the flexibility to design your system as per the requirements. Industrial air conditioning is slightly different form comfort air conditioning. Please refer ASHRAE or CIBSE relevant standards for more information.

The question is too general in scope to give an answer. I strongly recommend you either retain a consulting engineering firm or the services of a design/build contractor, both of whom should be well versed and experienced in HVAC design and installation. A split system has the flexibility of allowing the selection of an air handling unit to match whatever static pressure is necessary to serve the room being conditioned. By contrast a self contained unit will normally be limited by the supply fan that is standard in the particular unit selected. A few manufacturers will customize a packaged unit but you are still advised to retain professional help to guide you through all this...the devil is in the details.

I agree! I called the manufacturer's engineer and had him do the work in order to sell me their product when I had a challenging AC vs mini-split problem. Gary

Your first question to your self is; what do you need, than followed by how much am I willing to pay.

Do you need a positive pressure room, what is my sensible heat load, Are people coming and going, etc.

If you need more than just cooling a fixed load than a simple split Will no do it.

Just put an air conditioner split/whatever. most of your instruments are from European/American countries where the ambient temperatures are very low hence in control room they give problems due to increase ambient temperature above 80F since they are not designed to go over.

Cool the room to overcome your tripping/safety limit cut-off problems.

Dear Mr.shiha,

First deduce what is the Heat Load (or Heat Removal) in the control room - by way of Heat dissipated from the equipment and no.of persons to remain and work. The AC capacity should be decided on the basis of 12000 Btu/Hr. You know the total Heat to be removed and add 10% margin, Total Heat/12000 Btu/Hr. and and Tonnes of Refregeration is derived and you can choose no. of units.

Secondly, Positive Pressure is not required.

DHAYANANDHAN.S