Where do I put this Server Room's air exhaust?

[Anon_Miner]

TL;DR Summary

I have a room which i want to use as a server room. i have an air vent to bring cold air into the room but no way to take the warm air out. where do you recommend putting an inward fan for highest proficiency?

Hey guys.
I have a room which i want to use as a server room. the devices need to work 24/7 and they get pretty hot. so it is imperative to keep the room cool otherwise the devices will be damaged.

I have an air vent to bring cold air into the room for the devices so their fans can suck in cold air and cool down their boards. but as the fans suck the cold air from one side, warm air comes out from the other side. There is no way for the warm air to escape the room.

Which is why i want to put inward fans to take the warm air out.
The main challenge is that my cold air vent is positioned pretty high so i fear if i put the inward fan high, it will suck the cold air that's coming in through the vent. Also putting the inward fan in the ceiling is not an option because there are other rooms above this room.
with all things considered, where do you recommend putting the inward fan(s)?
Is it better to use one big fan or few smaller ones?

P.S: sorry for such simple schematic, I was using paint. all the devices are the same model and have the same dimensions and power usage.

 

[davenn]

Hi there
welcome to PF

I have a room which i want to use as a server room. the devices need to work 24/7 and they get pretty hot. so it is imperative to keep the room cool otherwise the devices will be damaged

better planning for a better purposed room would have been a good start. server rooms generally need significant air-conditioner units

Can that cool air input be relocated at floor level ?
If not it needs to be piped relocated to floor level and the rising hot air extracted at the top.
where is the door ?
Is there air -conditioning in rooms outside this room ?

how about some actual photos of the inside and outside of the room
they would be much more helpful than this crude drawing Dave

 

[russ_watters]

Cool air should be supplied low and warm air exhausted high.

 

[Klystron]

Depending on your budget an effective method to supply cool air below the servers racks is to install a 'false floor' above the rigid floor. Pipe the cold air under this layer to appropriate vents under the server stacks creating a plenum. Your equipment racks can stay attached to the original floor. Re-purpose the original overhead discharge vents as a warm air outflow that either exits the data center or enters the heating system.

Fans can be added to the output side of the discharge vent ducts with the option of thermostat controls so that the in-duct fans power up at a set temperature when needed. I suggest consulting with a HVAC (heating, ventilation, air conditioning) engineer for the design phase and using HVAC techs during implementation.

Keep the under-floor plenum free from cables and other impediments to cool air flow. Usually fans are not required under the false floor as the motors add unwanted heat with slight benefit given a proper design.

https://en.wikipedia.org/wiki/Plenum_chamber

 

[sophiecentaur]

I have a room which i want to use as a server room. the devices need to work 24/7 and they get pretty hot. so it is imperative to keep the room cool otherwise the devices will be damaged.

It is necessary to know the total electrical load involved with the servers. Engineering only works when the numbers are known. Also it would be important to know what the highest likely input air temperature would be. Without some proper data you could find any advice is just inappropriate - costing you more than necessary or not providing enough cooling.

I could suggest you get a quote from a local heating / ventilation firm. They would tell you some ball park figures for cost and a spec..

 

[davenn]

as @davenn said,
Cool air should be supplied low and warm air exhausted high.

 

[sophiecentaur]

I could suggest you get a quote from a local heating / ventilation firm. They would tell you some ball park figures for cost and a spec..

Or you could find an Aircon / heating forum which could have members with direct experience of this sort of problem. You may need to be prepared for bad language and hostile attitudes from some of the 'experts'. PF is a very gentle environment to stray into, compared with the rest of the jungle out there. It could be worth it though.

 

[Rive]

It is necessary to know the total electrical load involved with the servers.

This, and the size of the vent hole.
Maybe the actual temperature inside when the servers are working.

 

[sophiecentaur]

This, and the size of the vent hole.
Maybe the actual temperature inside when the servers are working.

yes - etc. etc. etc..

The server boxes will presumably have some specified working conditions (ambient temperature, for instance) and you can probably rely on their internal fans to cope with that.

 

[Lnewqban]

Anon,
You have a difficult problem to solve and errors may be costly.
All the above advice is solid, in my opinion.

I would only add that a server room requires no ventilation, but narrow control of temperature and humidity.
Specifically designed equipment (expensive), properly distributing air, can achieve that control.
A less expensive solution that works in some non-critical cases is the installation of one or more mini-split systems.

The calculation of the needed cooling capacity should be based on servers manufacturer's requirements, actual and future energy input (volt-amps consumed by all equipment at peak times), plus any heat load coming through the envelope of the room.

The main problems that I see with the proposed ventilation are dust and humidity control.
You have mentioned cold air supply, but have not clarified whether or not it is natural or mechanically cooled.
If natural, in rainy days it may remain cool, but you will be supplying the servers with humid cold air that may induce condensation in the room.
If conditioned air, you should return the air to the handler for recirculation, rather that exhausting it out, in order to avoid unnecessary latent loads.

It seems that when you mentioned "inward fans", you really meant exhaust fans.
Exhaust fans keep the room at negative pressure and avoid undesired hot air migration into adjacent occupied rooms, besides not adding the heat of the motors to the room's environment, as explained above.
If your weather if fairly cool and dry and ventilation is your only option, yes, you will need a supply duct distribution system, equipped with air filters, to properly reach all the servers.
Always consult with local Code authorities before expending time and resources.

 

[sophiecentaur]

a server room requires no ventilation

That implies that heat pumps (of some description) would always be needed. Wouldn't that put the cost up unnecessarily? I suppose a reverse flow heat exchanger could also do the job but even that could be over the top.

 

[Tom.G]

Servers you need to keep cool and clean. Just circulating outside air will keep them cool part of the time (depending on climate), keeping them clean is more difficult.

Maintaining a few computers in the near-suburbs I had to remove the motherboards and graphics cards about every five years, submerge in distilled water, agitated wash with a touch of detergent, rinse, rinse, rinse, dry, reassemble. This was in a moderately clean office environment with air conditioning. Also had to clean fans, heatsinks and filters every month or so. Now I'm retired in a new building with one computer, fans, heatsinks and filters are good for 2 to 3 months between cleanings.

So, yeah, if the labor is free and downtime is not a concern, just use outdoor air. You will soon get tired of the maintenance headaches though. Near an industrial area or a body of salt water it would be worse.

Have Fun!
Tom

 

[russ_watters]

I would only add that a server room requires no ventilation,...

In most of the world, this isn't correct. ASHRAE standards and the IMC require a small amount of ventilation for all occupiable spaces.

 

[Dullard]

I'm still struggling with the concept of supplying cold air to a room where: "There is no way for the warm air to escape the room." Based on the location of the supply vent (in the OP diagram), I think that's what he (literally) means.

 

[russ_watters]

I'm still struggling with the concept of supplying cold air to a room where: "There is no way for the warm air to escape the room." Based on the location of the supply vent (in the OP diagram), I think that's what he (literally) means.

You are right; that would violate conservation of mass. There must be a way for air to escape even if it is just a hole in the ceiling.

 

[sophiecentaur]

You are right; that would violate conservation of mass. There must be a way for air to escape even if it is just a hole in the ceiling.

He could just be getting a high pressure in the room. Easy to detect by a change in the note of the fan when the door is opened. It's not uncommon and it's a waste of the fan's power supply.