You cannot tax a corporation. Increased tax burdens just trickle down to reduced wages for low level employees and increased prices. I'm not sure why that is so hard for people to get.

Uh, voltage doesn't go negative, it goes to zero, unless you have a bulb that is magically producing voltage potential greater than the hot line.

It was built for the Vice President, not just Dick Cheney. It cost of millions of dollars and now useless.

That is where the ice storage systems become interesting and cost effective. In the states, usually half of a commercial energy bill is peak demand. If you can transfer that energy usage to night time to build up your ice storage and transfer your main power draw to off peak the savings can be very significant and create payback times in months not years.

Our design conditions were 75degF. The server manufacturers said they can handle up to 100degF but have much longer life with cooler room temps.

Primary loop is feeding the chiller. Most chillers don't like variable flow. The secondary loop is feeding the load.

The units were mounted on the roof, but were packaged AAON 2 x LL210 chillers (and a full 400 ton backup) with no exposed exterior piping. Glycol reduces the specific heat of the fluid and increases the specific gravity, so it can move less heat and takes more power to move. I only add glycol to the system if freezing is an issue.

I guess I was unclear, 80% of the circuit size(s) delivered to the units since you can't load a circuit to more than 80% of the breaker size.

1 ton is a unit of cooling equal to 12,000 BTU/hr, not weight. The typical rule of thumb is 2.4 GPM per ton which is based on a standard 10degF delta T, usually 44degF to 54degF. Assuming 100 feet of head and 50% mechanical efficiency, 1 BHP will move about 20 gallons of water per minute. 1 BHP is about 0.75kW.

I am kind of confused about how many kW of power it takes to transfer heat. Heat moves from high to low, you have to pump cold water through a coil and force warm air across that coil. The amount of heat transferred is a function of the face velocity and temperature of the air across that coil, the amount of fluid moved and temperature through the coil and the characteristics (fin spacing, fin size, material) of the coil.

The temperature of the computers isn't really the important factor, it is the heat rejected. Again using rules of thumb, you can assume that 80% of the electrical power delivered to the computers will be dissipated as heat. The total of that heat rejected along with the other heat inputs to the space, e.g. lighting, walls, roof, window loads, etc., will determine your cooling load. Almost all of this load is sensible, meaning heat only, for other occupancy types you would also have to consider latent (moisture) loads as far as people and ventilation air in determining the amount of cooling needed.

If you have chilled water, you have a chiller, which means you have compressors. Process water or ground source water usually is not cold enough to be an effective cooling medium. You want a high delta T between the entering air temp and the entering water temp to induce heat transfer. Closed loop ground source water is extremely (prohibitively) expensive and open loop is quite a maintenance hassle due to water treatment. High efficiency chillers paired with evaporative cooled water towers with economizer capability is very efficient and reliable. Usually you can get down to around 0.5kW per ton with high efficiency chillers at full load and with multiple staged compressors you can do even better with part load conditions. The cooling towers are usually pretty low with around 0.05 to 0.15kW per ton. Use VFD's on the secondary pumps and cooling tower fans, and you can get cooling in at 0.75kW per ton for the whole plant at peak and even lower and part load conditions (95% of the time).

I just designed a data center for a large Big Ten univeristy and there were no large air handlers involved at all. The system had two 400-ton chillers with the chilled water piped directly to rack mount APC fan coils. Without "green" being the basis of design, the chiller system still operates right at about 1kW/ton.