Originally Posted by caseym
i work for thermo king so i can get very good pricing from our local wholesaler of HVAC systems/parts. so i can't really justify paying $$$ for a professional to do the whole job and triple charge me on the unit.
paying $100 for someone to do a manual J work-up on such a small job seems worthless, as the cheapest/smallest units will probably suffice. cost is a major issue. don't wanna spend more than $1500. i don't care about efficiency as i will probably be moving soon. i just want something cheap.
Do it cheap and screw the person who buys your house in a couple years, right? Sorry to be so blunt, but that's exactly what comes across in what you are asking for.
Are you computer proficient with technical programs? If so, spend $50 and buy the use of HVAC Calc for two months. It's a pretty decent program and will give you the exact answers you're looking for.
Your comment about efficiency (I presume you mean SEER and AFUE) is understandable, and I took the same approach when I changed out my system 3 years ago. But, I made darn sure the system was the right size, and I did it with HVAC Calc. 900 sf house doesn't guarantee you'll get by with the smallest unit. It depends entirely on what the walls are made of, how well they are insulated, how good the windows are, and so on. HVAC Calc will help you factor all those in. What you DO NOT want to end up with is either an undersized or oversized heating unit or AC unit. Over or under creates discomfort. On the other hand, you may find your heating/cooling load is so low you can't find a central system that small. In that case wall units may well be the best solution, and possibly the cheapest. Don't sell short the value of doing Manual J calcs, even though they are not 100% accurate.
You'll find potential buyers will be greatly impressed when you tell them you made sure the heating and cooling system is sized right, and you know they will be comfortable both summer and winter because you were. That right there will make $100 look like chump change, if you opt to have someone do the calc for you. There are some free heating/cooling calc programs on the net, but I can't tell you how good they are.