I'm planning for my server room and need some guidance on how to manage my AC units during power fluctuations. Should I connect the AC units to the UPS circuits? What steps should I take to protect the AC units from power outages until the generator kicks in?
8 Answers
I wouldn’t recommend putting AC units on UPS. Look for an AC that can automatically restart after a power interruption. Battery prices are dropping, so consider a commercial grid battery system if you need your AC to run for an extended time after a power failure.
AC units require a few minutes to reset after a power interruption, so you need to account for the inrush current. Make sure your generator can handle the extra load when all AC units kick back on. I've set up large fans on thermostats as a temporary solution during outages to manage the heat until the AC is back online.
Last place I worked, we managed to keep everything running fine with our backup generator. The servers can handle a little heat, and the CRAC units aren't tied to UPS power, so no issues there. If the generator kicks in quickly enough, you should be okay.
Honestly, it all depends on your setup. Typically, AC systems aren't on UPS, but it's important to ensure everything is backed by generator power to minimize downtime.
Based on my experience, HVAC systems often fail during street power outages and only kick back in when the generators start up. If you're working with high-density server setups, it's critical to have a cooling solution on UPS if you can't afford even a short interruption in cooling.
Absolutely, I've seen this happen too!
Good point! Also, make sure your electronic dampers are on the same circuit as the HVAC, learned that the hard way!
Choosing to go with generator backup instead of UPS for AC is pretty common in many setups. Most modern server equipment is designed to operate well in warmer environments, so temperature spikes aren't usually a big concern.
The size of your server room and the number of servers really dictate the setup. For larger installations, it might be necessary to connect AC units to UPS for backup power, while smaller setups can often manage fine without it. Just remember, equipment can usually handle some heat temporarily, so don’t stress about a perfect 70°F all day, every day.
Yeah, we aren't that big either. We trust the generator to kick in fast enough to avoid overheating.
In general, keep your AC on backup generator power rather than UPS unless your entire facility runs on UPS. Most generators start supplying power within 30-60 seconds after a power loss, and that timeframe usually doesn’t heat up the room too drastically, especially if it has a decent thermal mass.
Does pulling in fresh air mess with humidity levels and risk moisture or condensation on equipment?