View Full Version : Commercial / Industrial Air Cond. query please

Krystal n chips
24th Jul 2006, 17:03
Whilst I am very well acquainted with the theory and maintenance of aircraft Cabin Air Cond. / Press. systems, I would be curious to know if there are any significant differences in the operation of Air Cond systems as used in large commercial buildings please given that I assume the principles remain the same ?--other than the aircraft related aspects of course--and that Commercial systems are designed to cool and produce large volumes of air.

The reason for asking is this. Just back from visiting my mother in hospital. She is in a small side ward and the window was open to it's maximum extent--say about 3ins top and bottom. In walks, have to be polite here and it's difficult believe me in this instance--a "nurse"--who says, and bear in mind the current OAT in MAN is about 28C---"I have to close the window so the air cond will work throughout the hospital" :confused: "Why"?, asks Krystal--ans--"Because senior management say so--that's why"----here endeth the "conversation" of course. So, a couple of thoughts spring to mind here--and bear in mind this a brand new part of the hospital--and it's difficult not to be cynical when "NHS" and "senior management " are mentioned in the same breath--but either (a) the system was never designed or anticipated to cope with prolonged periods of heat as per the current air temps ( b) the system was rubbish to start with--cheap option = best value of course or (c) somebody has realised that the cost of running the system in the current conditions is likely to have a significant impact on the / their budget.

Complaining to the hospital would be an excercise in futility of course--NHS "management" are a law unto themselves--and I don't intend to take matters further---but I am curious as to the rationale--or otherwise--behind the edict and wondered if there was a valid basis for the order as it relates to the Air Cond system.

24th Jul 2006, 17:38
Well I guess it would be like driving along in a car with the window open and the A/c an full blast.

Without enclosing the space, you are trying to cool the world.

24th Jul 2006, 17:49
Exactly - do you leave the door open on your fridge, K'n'c ? Or the lid off your Thermos flask ?

If you want the air inside the building to be a different temperature than outside, then it's very silly to open the windows and let them mix, isn't it ?

You wouldn't leave the windows open with the heating on. The laws of thermodynamics being what they are*, it costs you energy to cool things down as well as to heat them up. Energy is money, so you're just pissing money out of the window - and ruining the planet to boot.

*First law: you can never win - the best you can do is break even. :(
Second law: you can only break even at Absolute Zero. :*
Third law: you can never reach Absolute Zero. :{

Krystal n chips
24th Jul 2006, 18:50
Fair points and I accept the reasoning and logic behind them----but , given the spacious designs of a modern hospital, the continued influx / exit of people and the basis that a combination of cooled and fresh air would offer a more healthy environment, surely the systems would be designed to cope with and supply such. A sealed environment, as proposed, would not be realistic or attainable would it ?-----excludes specialist and designated areas obviously.

24th Jul 2006, 21:49
Just ask the Cabin Crew if you can open a window next time you fly . . .

As an aside, MY car has Climate Control. If I drive with the windows open and the target temperature set 'above ambient' the heater works overtime trying to bring the interior up to temperature. (Just as setting the target temperature BELOW ambient and driving with the windows (even partly) open will send the air-con into overdrive.)

24th Jul 2006, 22:48
As an aside, MY car has Climate Control.

If we have climate control, does this mean we can stop global warning:} and get it to rain in the Sahara and get the Thames to flood severely just by Westminster Bridge?

Windy Militant
24th Jul 2006, 23:01
Yes having the window open does affect the system. In a previous existance I spent many hours with a portable anemometer, several cans of WD 40 and a mole grips balancing the flow on air conditioning plant.
We usually did this on a weekend so it was fairly easy to keep control of doors windows etc. Come Monday morning we'd start getting alarms because people would be too hot or too cold and would start opening doors and windows.
Mind you we did feel a bit sorry for the poor guy that looked after the phone exchange in the main computer area. They'd just junked a big IBM mainframe so we spent a Saturday closing the vents in that area to increase to airflow into another area. What we hadn't realised that between the two areas was a little cuby hole for the phone techs. I still wonder what the guy thought as with each vent we closed the airflow increased. When we wandered over on the Sunday morning the poor guy was sat there in his parka with the hood toggled down tightly and wooly mittens on and a pile of house bricks holding down his paperwork against the howling hurricane that was coming from the vents directly above his desk.

24th Jul 2006, 23:02
If we have climate control, does this mean we can stop global warning:} and get it to rain in the Sahara and get the Thames to flood severely just by Westminster Bridge?
Only if everybody leaves their windows open.

24th Jul 2006, 23:10
Reminds me of the guy who was talking about his divorce settlement:

"Well it was quite fair, I suppose. We split the house 50-50 . . .

. . . she got the inside :{ "