Garage heat extraction

eddiewakey · 18 Jun 2017

not sure if this is the correct place so forgive me

I have a few severs running in my garage. And with the warmer weather it's gettnning hot in there.

The servers themselves are fine temperature wise, but the ambient temp in the garage is about 36-39 degrees.

So my first thought was to put an extractor fan st the back end of the garage high up to draw some of the hot air outside - I then assume "cold" air will get pulled through the gaps in the garage door.

Is this the best way to go about this? And is a kitchen fan with a higher rate the best solution? Seen screwfix have one for £20!

Thanks guys

deadshort · 18 Jun 2017

You need an AC unit!

DS

eddiewakey · 18 Jun 2017

Ideally - but that's too expensive so I'm thinking quick short term wins.

Am I expected to see a drop in ambient temp with a high level fan sucking some of the air out?

John D v2.0 · 18 Jun 2017

Yes with a fan you'll reduce the temperature slightly but not much with a bathroom one. Kitchen would be better, but even better make a cupboard for the servers and just duct the fan to/from that and the outside wall. You'll get a lot more air changes with a cupboard than the whole garage.

eddiewakey · 18 Jun 2017

Kitchen one was what I was looking at so thanks for that!

Interesting idea
How would you do it? Inlet in the front bottom (drawing air from garage) and outlet/hose/fan venting at the top to the outside?

John D v2.0 · 18 Jun 2017

Not quite, the inlet would have to draw the air from outside, otherwise you'll be pulling the warm air from the garage so the cupboard won't help.
The outlet I planned to go outside, but actually you can exhaust it to the garage.
Put the fan in the inlet, then you won't have to make the cupboard airtight as it'll be under positive pressure. If you put it in the outlet the cupboard will be negative pressure relative to the hot garage.

John D v2.0 · 18 Jun 2017

A bathroom one is usually around 15l per s, so 0.015 m3/s. If your cupboard is 1.5m3 then a bathroom fan will give 1 air change every 1 min 40.
So with the cupboard idea you should be fine with a bathroom fan.
Your garage is probably up tob50m3, so trying to do the whole garage could be ~1ach

Also think about noise and power consumption. You don't want to use >1w/l/s and try to move 60l/s 24 hours a day if possible!

eddiewakey · 18 Jun 2017

It's 15m2 if that helps. What you mean 1ach?

This is the one I was looking at

http://www.screwfix.com/p/manrose-xf150bs-25w-6-ceiling-wall-mounted-kitchen-fan/11640

So 230m³/hr

Tigercubrider · 18 Jun 2017

My garage is cooler than outside- given that he needs ac only in v hot weather does he need an outside intake if the servers are boxed in?

He probably needs a good brand designed for long term use as kitchen fans often are expected to run for 1/24 . From other experiences if enclosed then a small fan on constant but low speed ( with thermostat) will extract heat and pull in cold air before it gets too hot

http://www.canford.co.uk/ENCLOSURE-SYSTEMS-RACK-FANS

eddiewakey · 18 Jun 2017

John D v2.0 said:
Not quite, the inlet would have to draw the air from outside, otherwise you'll be pulling the warm air from the garage so the cupboard won't help.
The outlet I planned to go outside, but actually you can exhaust it to the garage.
Put the fan in the inlet, then you won't have to make the cupboard airtight as it'll be under positive pressure. If you put it in the outlet the cupboard will be negative pressure relative to the hot garage.

Doing it that way - will that result in the ambient temp in the garage itself been lower? As the air going into the cupboard would be colder than what it's getting now?

John D v2.0 · 18 Jun 2017

15m2 would be about 50m3 then.
Ach is air change per hour. Basically your 230m3 fan will give nearly 5ach.

Tiger has a good point, you want to check the duty cycle of the fan. Although anecdotally I have the fan part of an old cooker hood running 24h to dry out my subfloor (on one of the lower settings, but still very strong) with no issues.
As tiger suggests if your garage is colder then outside it's better to intake from there. Thermostat is a great idea and very cheap if you get a one with normally closed and normally open contact.

John D v2.0 · 18 Jun 2017

eddiewakey said:
Doing it that way - will that result in the ambient temp in the garage itself been lower? As the air going into the cupboard would be colder than what it's getting now?

That would result in the outside being coolest, the cupboard second, then the garage warmest, but the garage would be cooler then it would be without the fan.

EFLImpudence · 18 Jun 2017

Hot air rises; fit a chimney.

eddiewakey · 18 Jun 2017

EFLImpudence said:
Hot air rises; fit a chimney.

That was another thought, a cooker hood would fit nicely above my units

EFLImpudence · 18 Jun 2017

You don't need a fan.

If you have a chimney (pipe through the roof), the wind will do the work - that's how they work.

diynot

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Garage heat extraction

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