Server Cupboard Cooling

bigjme

bigjme

bigjme

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Joined
18 Mar 2013
Posts
67
Hi All,

I hope this is in the right place as i'd count this as more of a DIY/home topic than anything directly on the hardware front

So as a quick cut to the end for anyone in a rush:
I want to build a server cupboard pulling cold air through the loft from outside in and then exhausting hot air out through the loft. Using "free cooling" and no option for an AC unit. Is this feasible considering humidity in the uk year round and has anyone done similar?

If you have a little longer, the full story is below

Full Story
I currently have a server rack in an open area and i would like to build a server cupboard where i have some available space to move the rack into so its not in the open. The available space i have is roughly 2m x 1m x 2.3m (w x d x h) and is the centre of the property leading off from a bedroom

Ideally this room would be sealed for security and to remove noise however this causes heat concerns
I do not want to run an AC unit and do not plan to so i am looking at air cooling solutions only.

Because of the noise aspect this rules out putting vents in the door to pull air in and out of the attached bedroom alongside hot air being exhausted out the house in the winter. My thought was to run a "free cooling" setup using 2 inline extractor fans using outside air for cooling

Each would run through the loft space to the outside using insulated ducting, with one drawing cold air in and another pushing hot air out with the outlet being in the room ceiling, and the inlet duct running through the ceiling to the floor so it was pushing cold air at the very bottom

The ducting would have course have back draft prevention in both directions and dust filtering on the inlet pipe to prevent dust getting into the room. The fan units i have been looking at are rated at around 350m3/h of air flow, without duct resistance this could in theory cycle the air in that room 76 times per hour, so even with resistance i'd imagine 30 times per hour is more than enough to keep things cool

Looking at the ashrae map for the uk, it looks like their air side cooling map states that the uk should be able to achieve over 8000 hours of free cooling per year (i.e. year round) with just air from the outside

My plan for this would be to setup a cooling controller to turn on the fans at a set temperature, then at another temperature turn the fans off. Allowing say a 3'c settling period in the middle and a small enough temperature drop that not a huge amount of air should be pulled in when its colder outside

I have seen many posts online for similar projects, but in almost all of them the usual "get an ac unit" is the answer which for my power load makes no sense and i have no way to get rid of moisture if i have a unit with a humidifier as well, or run a door vent which introduces noise and would mean exhausting warm air from the house in the winter directly out the roof since these rooms site mostly at 22'c

So the simple part is, is anyone running anything similar specifically here in the UK or is this just a pipe dream and i should just leave things as they ae which works fine?

My main concern is the humidity in the room and moisture on components rather than the cooling capacity. A dust filter will remove some to moisture to an extent but not huge amounts and with weather like now (0'c outside with 82% humidity), the system would hardly be kicking on throughout the day besides the odd push to rapidly decrease the temperature of the room but that humidity level is a concern

Sorry this has ended up as a wall of text but as always, information is key to a good solution

Regards,
Jamie
 
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The moisture from the ac unit normally goes to an internal tank and needs to be dumped somewhere i.e. manual emptying or plumbing it into a waste of some kind, not many exhaust moisture out the ducting itself
The planned location has no way of directly removing the water via a plumbed solution and i would hate to have to go and empty it all the time otherwise
 
Sadly its a fairly small house so no shed/outhouse and no garage so its really just limited space. The available space i have is really where is is now on a landing or the proposed space which is a cupboard off a bedroom
I watched those a few days ago whilst trying to research this but the AC unit itself pulling over 750w for even a small unit, this is more than the machines themselves so it just feels very un-needed. The ideal is to avoid AC at all costs

This is where i'm thinking it may not be possible due to humidity in the outside air and it may have to just stay where it is. I'm not apposed to leaving it as is but a cupboard would be better if possible
 
Sadly no access underneath, its directly above the staircase so its a hall way below part of it. The ducting itself is less of an issue, i have available places to run it above without issue and hopefully the below should explain why the loft should be fine for this, the primary concern is if it would work without causing damaging condensation

Regarding the ducting, i would be using insulated ducting for this with a kit something like this
The insulated ducting is designed to prevent heat loss and heat gain from the areas it goes though. This should prevent condensation forming at all in the ducting in the cold, at least that's how their meant to work anyway

My biggest concern was condensation but not in the ducting, rather on the server equipment. So basically if it was running now, if the heat hits 23'c which is likely at least a few times per day, the vents would pull out all the air in the room in a minute or so and fill it with 0 degree air. That would be bad
But as long as i monitor the room temperatures near the inlet, as the temperature drops due to the cold air being pulled in, it would detect 20 degrees and turn off the intake so it may only be on 10 or 15 seconds

The air in the room should then equalize temperature wise and should it not be enough air, the fans would kick back on at 23 degrees
This would repeat fairly often i'd imagine until it evens out between 20 and 23 degrees

The time it takes for this to happen could be altered based on where i put the probe in this instance. Directly in front of the inlet will cut the air off very quickly allowing small amounts at a time - but this is likely bad for the fans (i guess?)
Placed near the inlet/front side of the server and it would take a little longer. The higher the probe the longer the fan would run

Sadly i don't understand condensation enough to know how long it would take of cold air being pushed in to cause it to form. It would be like opening a window in a warm room for a minute.
At that point i would not expect condensation to form on warm objects even if done very often throughout a day

There should be enough control and available cool(ish) air year round to keep the servers from getting hot, condensation is the main killer so really it would be great if anyone else is running similar to see what their experience has been like
I did see some people running server in their loft space and exhausting air outside and using loft air for the intake but in the summer i know my loft gets extremely hot otherwise i could just pull in air from there as its likely to be less humid than outside (in theory)

The easiest solution is to pull air from the house which would be more conditioned and put fans on the door inlet with noise dampening to help with the noise.
This has the downside that it would be exhausting hot air from the house fairly often causing the heating to run more making its own issues

Looking online and on this old thread from another forum it looks like condensation will form if warm air hits a cold object but not the other way around so my warm cab should not form condensation if the air coming in is colder. Even at 82% humidity outside, once inside and warmed up by the remaining server room air it should reduce the humidity to a more comfortable and acceptable level. And it seems the lower the room heat the higher the humidity is likely to be in the room so perhaps changing the room temperatures could help even out the humidity if it started to drop low
 
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At this point I'd like to say thank you for all the input but I have a feeling this will likely go nowhere

No the servers are not old, the primary is maybe 6 months old at best. They are not the kind of thing you can run remote, as stated previously although now removed, one hosts gaming vm's and workstation vm's, multi gpus per box so they have to be local

This discussion was not regarding hardware, or anything else. It was a simple question, has anyone done this before, if not then that's fine i will not proceed further

As I very politely stated many times, i do not wish to run AC in this situation
This was just to see if this was viable. This option would be better for me, but if not possible or viable then it simply isn't

Again, thank you all for your replies and sorry if you have wasted your time replying so far but I think I will call it there unless someone has done similar in the past
 
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I had looked at a MVHR actually, i was unsure due to the air circulation on them for smaller units, below £400 ish your looking at 56m3/h to 110m3/h by the looks of things
Which is actually not too bad considering the size of my available space.

This may actually be the way to go as it simply mixes the hot exhaust air with the cold incoming air to pre-warm it before entering the room so its not as cold
Its very similar to just letting the cold air into the room and allowing it to mix naturally but with less chances of a cold spot where it comes in
 
When pulling air out of a room it has to be replaced from somewhere. Normally you extract air out the room and it would pull in from under doors etc.
With large capacity ducting you could put a vent in a door potentially with additional fans to push air into the room. You therefore extract air into the loft and outside and cooler air enters the room through the door

In my case the winter is the killer as 22'c air being pulled into a room and then being exhausted means cold air enters the house from somewhere and has to be warmed up again
I hope that helps?


Edit
For anyone interested, i did find some posts from 2012 of someone in Manchester running the exact setup i asked about in a number of locations and they worked well for them. I also managed to find some documents from 2015 which ran through a similar setup in the UK. Each just using a HEPA filter to remove dust.
So it does seem possible although the number of people doing it seems extremely low and there is never much details into exactly what they setup and how it worked year round.

For example, the MVHR is great in the winter but you need to get one with a summer bypass as otherwise in the summer your pulling in hot air from outside and likely warming it up further with exhaust air
 
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So one last follow up as i think this idea is fairly sound. Having remembered the linus from LTT has an enclosed server room at home i checked back on his setup video
He has a single duct fan pulling directly from outside (without a dust filter) as ~200cfm cooling his server room with no exhaust, all host air ducts to the loft space passively

He has so far had this running for 5 years and i'm sure we would have any update video by now if it did not work. Vancouver temperature and humidity year round sits very close to the weather here in the midlands (UK) with our average humidity actually around 4% lower year round
Based on that and the other threads i have found i think this is likely to go ahead at some point but with an inline dust filter, something like a G4 filter should do it i think...
 
So, as an update for anyone still interested or seeing this in the future, i have learnt a lot in the last 8 months

I have a friend who has gone down the venting/ducting route and struggled massively over the summer. It simply was not able to cope and required a portable AC unit to keep things under control
I have now opted to go for a Panasonic (a+++ rated) multi split ac setup for the server room and another room

For anyone who may want to know what i have found and what i found useful to know:
  • A good multi-split will spin down to very minimal power usage. My units will pull 250w to cool 1.1kw of heat on its lowest speed
  • 2 high performance ducted fans were going to pull around 160w 24/7 to cycle the air properly, so in reality, the power difference is not much
  • The condensate lines from the internal units can be connected to an ac pump that pumps the condensate to the outside unit - I am going down this route
As an overall, AC was the way forward for me so thank you for everyone that did recommend it. There was a lot to learn and research and my objection to it ultimately was related to lack of knowledge
Price wise there is a large difference for both systems but for the benefits of the ac (filtered, no humidity issues, solid temperatures) and the relatively low extra power cost (90w), at this point i would suggest it

I will however comment back at some point once the whole system is setup and running to comment on power consumption. Whilst it should pull minimum power, this may not be the case in reality so we will see :)
 
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