Don't get me started Guys.........
Where to start.......?
1: Normal AC = 400 CFM/ton
Server Room AC: 500 - 750 CFM/ton
Daikin AC = 300 CFM/ton..........so much for sensible heat efficiency.
2. Hot isle, cold isle, short circulation loop on the short end of the Server Rm.
3. Server room filtration...Daikin sponge rubber filters.....enough said.
4. Low server room ambient conditions.....Diakin to the rescue......NOT!
5. Ect, ect, .........
John J. Dalton CM
One size DOES NOT fit all
The fundamental problems I see when incorporating ductless mini-split systems for high density server or date rooms is as follows:
1. The minimum CFM/ton of cooling should be in the range of 500 to 750 CFM/ton, at best these are what…. 250 CFM/ton, the sensible/latent heat ratio of these units make the system inefficient from the start.
2. The air changes per hour of these newer denser server or data rooms are increased from the normal 4 to 8 AC/Hr. that one would see in a typical office area to well over 200 AC/Hr. making air filtration an extremely important factor. These units are equipment with minimal return air filter area with minimal efficentency.
3. The air characteristics of a modern dense server or data room call for specific airflow of both the return and the supply air into and out of the room, these systems do not poses the flexibility of other than normal window unit type airflow and directional movement.
4. What do these units poses in way of a low evaporator heat load condition in the room? What about low ambient operating temperatures when full cooling is required in the room?
Inverter control of the compressor in DX systems have made a small, but important dent in the more conventional chiller type systems for close capacity control, but there has to be more to a server or data room system than this alone.
Given the way things are progressing in our industry, I’m sure that in time, these systems will be designed, built, and installed specifically for these types of rooms, but until then, lets not make one size system fit all.
Just my option…………
John J. Dalton CM