Air Conditioning - True BTU rating?
Doityourself.com community forum was created to provide answers to all questions related to home improvement and home repair. Doityourself community can help you find information about how-to topics on small fixes to large remodeling projects. With comprehensive how-to content and expertly moderated community forums DoItYourself.com makes it easy to tackle even the most complex home improvement projects.View Full Version : True BTU rating?
NLAlston
07-17-05, 04:23 PM
Hi,
I touched on this in a continuation of another thread of mine, but thought that maybe I should have opened a new thread on this concern (that it would grasp more immediate attention this way).
While recently at a store (Rosa's) I noticed that all of their AC units had the manufacturer's sq/ft coverages (on the unit's tags) crossed out - and lower figures written in by the store. On one 9,000 BTU portable AC unit there had been the manufacturer's statement of 400 sq/ft coverage on the tag, and yet another another statement of 425 sq/ft coverage on that unit's box. The worker, there, informed me that the realistic number for a 9,000 BTU AC would be about 300 sq/ft coverage. A 10,000 BTU AC would yield approximately 50-75 sq/ft more. Yet, I read elsewhere that a 10,000 BTU unit would handle up to a 500 sq/ft area.
So, could someone PLEASE share with me some very realistic coverage numbers for units bearing the, say, 9,000 - 15,000 BTU units? I did pick up a Windchaser 10,000 BTU portable AC (this one listed no sq/ft coverage at all) due to having to take the 12,000 BTU window/mount AC back (problems). The portable is doing just a fair job of cooling down, and I think that I will take it back just as soon as get some more (different models) in. The concerned room is about 420 sq/ft, and I don't really want to go into overkill because of the associated problems that could surface. I would just like to get into something that could be expected to do a fine job of cooling this area - and without strain.
Oh yes, I forgot to mention that the room we desire to cool is the family room, and there are six of us here (two adults, four children).
I touched on this in a continuation of another thread of mine, but thought that maybe I should have opened a new thread on this concern (that it would grasp more immediate attention this way).
While recently at a store (Rosa's) I noticed that all of their AC units had the manufacturer's sq/ft coverages (on the unit's tags) crossed out - and lower figures written in by the store. On one 9,000 BTU portable AC unit there had been the manufacturer's statement of 400 sq/ft coverage on the tag, and yet another another statement of 425 sq/ft coverage on that unit's box. The worker, there, informed me that the realistic number for a 9,000 BTU AC would be about 300 sq/ft coverage. A 10,000 BTU AC would yield approximately 50-75 sq/ft more. Yet, I read elsewhere that a 10,000 BTU unit would handle up to a 500 sq/ft area.
So, could someone PLEASE share with me some very realistic coverage numbers for units bearing the, say, 9,000 - 15,000 BTU units? I did pick up a Windchaser 10,000 BTU portable AC (this one listed no sq/ft coverage at all) due to having to take the 12,000 BTU window/mount AC back (problems). The portable is doing just a fair job of cooling down, and I think that I will take it back just as soon as get some more (different models) in. The concerned room is about 420 sq/ft, and I don't really want to go into overkill because of the associated problems that could surface. I would just like to get into something that could be expected to do a fine job of cooling this area - and without strain.
Oh yes, I forgot to mention that the room we desire to cool is the family room, and there are six of us here (two adults, four children).
Cheech
07-17-05, 04:51 PM
400 sq/ft per ton of refrigeration 1 ton being 12,000 btus.I would go with 1 ton considering the number of people in the room.
Grady
07-17-05, 07:26 PM
Square feet mean ABSOLUTELY NOTHING.
GregH
07-17-05, 07:47 PM
NLAlston,
Your question asks what is a realistic square footage rating for a given amount of cooling.
The answer is that it is unrealistic to size any type of a/c by square footage, especially when you are not cooling the whole space.
Cheech's 400sq.ft./ton rule of thumb does not apply everywhere. Where we are, a 1200 sq ft. modern house here in mid eighties outdoor temp and 60% rh can be nicely cooled with a 1 1/2 ton unit.
The size of the room you wish to cool will have a bearing on what capacity unit you buy but there are other factors; Is the room able to be totally isolated from the rest of the house, how good is the insulation and are the windows energy efficient. How many people will be in the room; an adult under vigorous exersize gives off 600 btu/hr/person.
My advice is that if you are cooling a room larger than a bedroom and less than the whole house, is to get the largest unit you can plug into a regular 15 amp 120 volt recepticle.,
Your question asks what is a realistic square footage rating for a given amount of cooling.
The answer is that it is unrealistic to size any type of a/c by square footage, especially when you are not cooling the whole space.
Cheech's 400sq.ft./ton rule of thumb does not apply everywhere. Where we are, a 1200 sq ft. modern house here in mid eighties outdoor temp and 60% rh can be nicely cooled with a 1 1/2 ton unit.
The size of the room you wish to cool will have a bearing on what capacity unit you buy but there are other factors; Is the room able to be totally isolated from the rest of the house, how good is the insulation and are the windows energy efficient. How many people will be in the room; an adult under vigorous exersize gives off 600 btu/hr/person.
My advice is that if you are cooling a room larger than a bedroom and less than the whole house, is to get the largest unit you can plug into a regular 15 amp 120 volt recepticle.,
NLAlston
07-17-05, 11:50 PM
My advice is that if you are cooling a room larger than a bedroom and less than the whole house, is to get the largest unit you can plug into a regular 15 amp 120 volt recepticle.,
GregH,
What you have suggested is exactly what I intend to do. I was somewhat concerned over getting too large a unit, for that room, largely due to raised fears over creating breeding grounds for mold. Also, it was mentioned that an oversized AC unit would translate into higher energy costs due to the near constant cycling on/off. I don't know as to well the insulation properties are, within those walls, but can say that it gets so very hot in there (the whole house, actually) during the summer months, and just as cold in there during the winter season - which is why we had a gas fireplace installed there, two years ago. I guess this would translate into the insulation values not being anywhere near where they should be. The 9,000 BTU portable unit that was recently bought showed an initial RT drop of about 5 or 6 steps, after running nearly three hours. It was left on all day, yesterday, and after dropping about two more steps, it began to show a rise in the room temperature - and that is the way that it had been reading (a continual rising) until we shut the thing down, just a few hours ago. I don't know whether it relates to something being wrong with the unit itself, or whether it just can't handle our request.
As earlier stated, this room is approximately 420 sq/ft, and it can be shut off from the rest of the home (no permanently open thru ways), and I will now be looking for the largest unit I can get for a 15amp service (and look into a dehumidifier, to boot).
I wish to thank you for your helpfulness (and all others, also, who responded).
GregH,
What you have suggested is exactly what I intend to do. I was somewhat concerned over getting too large a unit, for that room, largely due to raised fears over creating breeding grounds for mold. Also, it was mentioned that an oversized AC unit would translate into higher energy costs due to the near constant cycling on/off. I don't know as to well the insulation properties are, within those walls, but can say that it gets so very hot in there (the whole house, actually) during the summer months, and just as cold in there during the winter season - which is why we had a gas fireplace installed there, two years ago. I guess this would translate into the insulation values not being anywhere near where they should be. The 9,000 BTU portable unit that was recently bought showed an initial RT drop of about 5 or 6 steps, after running nearly three hours. It was left on all day, yesterday, and after dropping about two more steps, it began to show a rise in the room temperature - and that is the way that it had been reading (a continual rising) until we shut the thing down, just a few hours ago. I don't know whether it relates to something being wrong with the unit itself, or whether it just can't handle our request.
As earlier stated, this room is approximately 420 sq/ft, and it can be shut off from the rest of the home (no permanently open thru ways), and I will now be looking for the largest unit I can get for a 15amp service (and look into a dehumidifier, to boot).
I wish to thank you for your helpfulness (and all others, also, who responded).