In the beginning, my house was unbearable. Tri-level in Arizona with 25 year old A/C, I guess you'd see what I'm talking about. Of course, I wanted it to be better, but didn't have the clue how, time to do it, or the money to do it, plus some common sense to investigate the problem before trying to solve it, so I ended up here.
I've read some things that I've never heard about, or paid attention to.
Like air return. Not a single house I've lived in either in Iowa, Illinois, or Arizona had it. My house didn't have it either, so after some consideration I've just cut the holes in the doors, and put the $6 "air return grill" items from Home Depot over them - worked like a charm.
In a last year, I've been asking all my friends and neighbors whether they have air return or not. Nobody did. That strikes me as funny, given that the proper air return seems to be a hot topic here, and we're talking about Arizona, where the cooling is critical.
Then, I found out about multizone systems. Brief estimate showed me that using off-the-shelf equipment is going to cost me something starting with $5000+ for entry-level equipment, which was out of question at the time. Then I started to explore the alternatives.
First useful source I've found was http://www.hometoys.com/htinews/aug99/articles/muziani/muziani.htm, but it didn't tell me how to actually control the servos with the computer. Well, that took some time, now take a look at http://servomaster.sourceforge.net/, you will find all the answers that I was able to dig since last summer.
Then there was a problem of the sensors, one of the obvious choices was X10, but I've rejected it after fiddling with the devices for a while - it is slow, not secure, not reliable. And the prices were just over the roof.
I ended up with using 1-Wire devices from http://www.dalsemi.com/ - a sensor is going to cost you about $3, and $10 for RS-232 controller. Same devices could be used to control the A/C - see the other thread named "controlling A/C with computer".
In the end, I have a multizone system that cost me (to date) $450 in parts, plus some labor, plus a lot of R&D, including, but not limited to, HVAC, embedded systems, process control.
Right now I don't have the actual A/C connected to it - there's a backorder on one of the parts that I need, but you can already take a look at the results here - it's working in a passive mode:
Take a look at the green line in the night on the 32 hours or 8 days graph - this room is controlled now. For comparison, take look at the cyan line. (update: the cyan line is also controlled since Feb 3)
btw, BamaCracker, remember the "Funny A/C behavior" thread? It did it again, as soon as the temperature dropped below the freezing point - on Jan 31. Hope I get rid of this unit soon.
The reason for this post is - I want to run it by the professionals, give some hope to HOs, and maybe we can do something better together
Anyway, my $0.02.
[Edited by vt on 02-04-2002 at 10:04 PM]