What are ventilation options for VERY hot room

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I'm not sure if this post fits here but I'll give it a go.

I have a small room with 3 machines running very hot (a compressor, suction unit & a desktop autoclave). No noxious emmisions are present but the room can rise to about 34C & intefers with other kit in there.

I was assuming a decent exhaust vent system would work but have had someone keen to promote a positive input option. To my mind this will just push the hot air out into the next room.

Anyone know what I should be doing? I seem to be struggling to find anyone who can provide a suitable exhaust option

Many thanks in advance for any guidance!
 
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Might need more information regarding ground level, single story, rooms layout etc
 
"Rises to 34˚" doesn't actually say much about how much heat you need to get rid of. What you need to know is how much heat your equipment is putting out, and (assuming it's all plug in stuff) one of those plug in energy meters is a good start - but make sure it measures true power. Note that the clip on energy meters intended to go on a meter tail are useless for this as they do not (and cannot) measure power.

The ones I have lying around have an accumulator so they will tell you hours they've been powered on and total power usage - leave on on all day and you'll get the average power used (at least 2 of your devices will be intermittent in power consumption and so it's hard to work out actual usage vs peak usage).
You'll also need to allow for other heat sources - other tools (soldering iron ?), people, computers, etc.

Once you know this, then you are in a position to consider options.
As a starting point, the specific heat capacity of dry air at atmospheric pressue is around 1.01 kJ/kg K, = 1.23 kJ/m^3 K. Or put another way, 1.23kW will heat a cubic meter of air by 1˚C/second.
When you know how much heat you need to get rid of, you can have a stab at an acceptable room temperature rise, and can then work out the air flow rate you need to get rid of it.

I've done a bit of this at work - we have a room with 7kW of fan heaters (otherwise known as racks of computers) to keep cool. That needs quite an airflow, and the hot end of the room is somewhere we avoid except when it's cold in the rest of the office :)
 
Move to an industrial unit if you are genuine.
 
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Thanks all.

Moving isn't an option, only venting, I just do not know whether in or out!

All the kit is wired in so I can't accurately measure power consumption, and they run on demand so are not always on. However, to be a little more accurate:

The room volume is 12m3, and rises from 20C at 9am to 34C by 4pm, so that's 2C per hour. I'm not sure how I would convert these numbers to a required air flow. Any takers?
 
You seem to make the same mistake that even professional ventilation designers have demonstrated.

Room volume is fairly unimportant. All it does is slightly increase the volume of air to be heated, but more importantly it also increases the volume (and hence thermal mass) of the enclosing walls. In the past I've gone to a (so called) professional will all the heat figures (ie how much heat the equipment is generating) - only for him to completely ignore them and use his rules of thumb based of room size :rolleyes: The figures you've given don't help in the required calculations.

If you can't measure the heat input, then you should try and estimate it. Clip on "energy monitors" may help, but be aware that these do not and can not actually measure poser - only estimate it from measured current while ignoring power factor and voltage variations.

As to in vs out, ideally you need both. A supply (intake) at one end of the room, and an exhaust (outlet) at the other will provide flow through the room and remove heat. You will, however, create a temperature gradient where the room is cold at one end and hot at the other - how big a problem this is depends on many variables (room height, air flow, "sensitivity" of the people).
If the room is high enough, trying to create an airflow along the ceiling will allow the hot air to rise up into it and be carried away - without subjecting people below it to excessive draughts. This is a design objective for air con systems where the air can be very cold when the system is working hard.
 
Thanks Simon

I understand that cooling is about moving hot air out & cooler air in, I was just uncertain as to whether the cold air should come from adjacent rooms or outside. The only place for a PIV input is in the ceiling, where the current (insufficient) extraction vent is. Not sure how this would push the hot air out of the room

The 'surveyor' didnt make any measurements other than to see if a PIV fan would fit. So perhaps he was keener on flogging this than looking for a correct solution.

I'll fix a meter to the mains & see what I can measure.
 
I understand that cooling is about moving hot air out & cooler air in, I was just uncertain as to whether the cold air should come from adjacent rooms or outside. The only place for a PIV input is in the ceiling, where the current (insufficient) extraction vent is. Not sure how this would push the hot air out of the room
Basically :

If you push air in, then it will leave by whatever means it can find. That may not be helpful if, for example, the main leak is under the door (where the air is coolest) and it leaves the hot air still in the room higher up. On the other hand, if you can push the hot air out into the rest of the building then it's free heating (though probably not when you want it).

If you suck air out, then it's replacement will come in from wherever it can find a supply. That may well mean sucking the warm air from other rooms, leading to you running the heating more to heat the rest of the building, while spending money throwing hot air away.

If you suck out the same quantity as you blow in, then you can control the airflow.

The 'surveyor' didnt make any measurements other than to see if a PIV fan would fit. So perhaps he was keener on flogging this than looking for a correct solution.
Surely you aren't suggesting a salesman might be less than 100% honest !


EDIT:
PS - you may be able to guesstimate the power going in by looking at the rating of the bits of equipment, and estimating how long it runs for. Be aware that rating plates (especially on IT kit) often over-state the power requirements, and things like ovens only have the element on in short bursts once warm.
 

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