GeneralThis forum is for non-technical general discussion which can include both Linux and non-Linux topics. Have fun!
Notices
Welcome to LinuxQuestions.org, a friendly and active Linux Community.
You are currently viewing LQ as a guest. By joining our community you will have the ability to post topics, receive our newsletter, use the advanced search, subscribe to threads and access many other special features. Registration is quick, simple and absolutely free. Join our community today!
Note that registered members see fewer ads, and ContentLink is completely disabled once you log in.
If you have any problems with the registration process or your account login, please contact us. If you need to reset your password, click here.
Having a problem logging in? Please visit this page to clear all LQ-related cookies.
Get a virtual cloud desktop with the Linux distro that you want in less than five minutes with Shells! With over 10 pre-installed distros to choose from, the worry-free installation life is here! Whether you are a digital nomad or just looking for flexibility, Shells can put your Linux machine on the device that you want to use.
Exclusive for LQ members, get up to 45% off per month. Click here for more info.
Something not computer related (although you can send me the solution in a spreadsheet ).
I like to know how I can convert the capacity of an air conditioner (expressed in BTUs) to something more 'human readable' (like delta(temp) per cubic metre) so I can calculate which capacity I need for a room of 150 cubic metre and a temperature difference of roughly 20 degrees max.
It's really more complex than that- a lot depends on the insulation and heat generating equipment. A room full of servers will take way more than a room with a TV
bryantrv is correct that it's very complicated, but here's some more help for you.
Find out how much electrical equipment will be in the room and calculate the total wattage used. Then multiply the wattage by 3.412. This is the number of BTU/hour that the electrical equipment will generate.
The prior two replies assume you're trying to cool a computer equipment room, not a house.
I just asked "Google" for "air conditioner capacity calculator," and the first hit was this. There were more than 2x10**6 "hits," so you might be able to find exactly what you want in the list.
[snip]
I would assume that the capacity depends on the volume but most of the calculators that I found just take the floor surface.[/snip]
Yes, of course. And on other factors. But, clearly, volume is linearly proportional to floor area, and -- in the U.S., at least -- most homes are built with "standard height" flat ceilings, seven feet (the U.S. does not yet use metric measures) above the floor. So, in order to "simplify" things, that assumption is built in to the calculator.
So, to use it, just compute the volume you're interested in, convert it to cubic feet, divide by seven. Then tell the calculator that you're interested in a room x by y feet where x*y = volume / 7.
Alternatively you could just plug a few easy numbers into the calculator. If, as I suspect, the calculator is using a formula like BTU = constant * x * y, then log(BTU) = log(constant)+log(x)+log(y), so log(constant)=log(BTU)-log(x)-log(y). Thus just putting a couple of numbers into the calculator should recover the formula used since the only "unknown" is the constant. Note that log(x)+log(y) is just log(area), so, if the calculator uses "area" as the input variable, then a single calculation should give you the constant.
In fact, let me see what the calculator to which I pointed you, above, yields.
Hum, O.K., that calculator is "slightly" more sophisticated, taking into account insulation, sun exposure, and heating. But the basic formula is about what I suggested:
Code:
BTU = 100 * area * insulation * sun_exposure + added_BTUs
where area = ciel(length * width,10), both measured in feet
insulation = (1.1, 1.2, 1.3, 1.4, 1.5)[excellent ... poor]
sun_exposure = (1.1, 1)[yes, no]
added_BTUs = (4000, 0)[kitchen, not_kitchen]
delta temp will vary according to the humidity, the volume of the room, AND the speed of airflow across the coil while BTU/hr is a direct measure of the energy the AC can move.
To cope with your problem under any circumstances, you want to calculate the rate of energy influx into your room (radiative, conductive, and due to sources into the room) then choose a unit that can move energy arriving at that rate.
LinuxQuestions.org is looking for people interested in writing
Editorials, Articles, Reviews, and more. If you'd like to contribute
content, let us know.