Upgrading our cooling system

It’s been almost 8 years since we moved the datacentre and had a new airconditioning system installed.  Overall it’s been working fine,  but we’re nearing maximum capacity and need to consider upgrading. As it also failed miserably about two weeks ago, and we have some decent winter temperatures (coldest January in 30 years), now seems a good time to look at replacing it.

Things to consider for a new system
– size/capacity
– redundancy
– free cooling
– supplier

I was never really happy with our current supplier (no need to name them). Originally, we chose them because they had already installed and maintained an existing cooling system in our buildings, but in retrospect it should have been clear that they had little or no experience with cooling a datacentre, not even small server-rooms. I don’t blame them, it was really our fault by not taking the time to do our research, and solicit a few proposals from different suppliers.
There is plenty of companies who do this type of thing, so for starters I’ve solicited proposals from three of them.

Capacity and redundancy
As Niels Bohr so wisely said “it is to difficult to predict, especially the future”. Trying to decide what we might need in the next 2-3 years is not easy, at all. Our datacenter is not that big, only some 40m2, and there is still plenty of room for expansion. Current power consumption is about 12kW plus the cooling system. The UPS is 15kW for now, but we already have a 30kW model in storage, so I am thinking we should aim for 20-25kW capacity for cooling.
As we’re expecting a new cooling plant anyway, redundancy is also a topic to consider. Essentially redundancy means a double system, so twice the investment.

Free cooling
When the current cooling plant broke down, we hauled out a big fan and installed it in the doorway. It simply draws in cold outside air through two 25cm venting holes, thereby easily maintaining a steady temperature of 15°C (outside -5°C). This has now been cooling the datacentre for about two weeks. It seemed reasonable to look for solutions for cooling with outside air, and after googling a while, I found the expression “free cooling”.
Free cooling devices are more expensive than plain air conditioning devices. At least that is my impression, I have not actually had any proposals yet. Some are very big, intended for large datacentres (100s of m2) with double flooring etc., but some also come in fairly compact sizes, intended for up to 30kW. The general idea is to reduce electricity consumption by utilising the outside temperature until it exceeds the target temperature for the datacentre. I have just today spoken to one possible supplier, it’ll be interesting to see where this leads.

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