air compressor room ventilation
We have three water cooled air compressor of 450 hp each. As per manufacturer recommendation (Sullair), there is also a need of 21 000 cfm of fresh air ventilation for the heat released by the compressors casing (260 mbh).
We also need to keep the room in positive pressure to avoid exterior dust to come inside so I was thinking to install a make up air of 21 000 cfm with recirculation, power exhaust and drives on the fans. However, I find this system quite big and expensive.
The second option I was thinking is to rather use a 20 tons / 7000 cfm, DX roof top unit which is twice cheaper. I did a quick energy saving calculation and this solution does not cost more to operate than the make up air system since much less air is used. Does this RTU solution make sense for an air compressor room?
Don't forget to add the room to your gain/loss.
I don't know much about your circumstance, such as location, heat loss/gain, utility, etc.
You really need an engineer to go over this. If you are in an area that can drop below freezing, the compressors will undoubtedly be able to supply enough heat if the ventilation is cycled on stat, but you may find, if you run the ventilation continuously, you'll need some heat, one way or another, just to keep the condensate warm enough not to freeze.
Is it really going to cost you less to run those refrig compressors continuously vs. one or two fan motors?
I heard you talk about positive pressure because of dust, but why can't you seal up the room, add 21,000cfm of exhaust, knock out some blocks on the other end of the room and install some high eff filters, changing them regularly? Add dampers if you need them. Run the fans on a discharge stat. It may still require some heat in winter, for all I know.
Are you looking to keep the room well ventilated or cool it to a comfortable 70F? Most air compressor rooms I've ever dealt with run fine at 90-100F room temp because the compressors are water cooled anyway. The air should be dealt with by autobleeds and the drier to haul the condensation out.
Next question: How is the air supplied to the compressors? Via exterior duct or takes it from the room?
Is this a Fabreze moment? C.Y.D. I'm voting white elephant. 2¢.