We have a Sharp room air conditioner, model AF 802M6. I need to know how many BTU's and the size of the room this air conditioner shoould be used in. Thanks for your help. I have a room with 273 sq. ft. What size air conditioner would you suggest for this siqe room? Thankyou for your help. Our present Sharp; air conditioner is at least 30 years old. Pretty good I'd say. Again, thankyou for your help. Barbara Parente