Honeywell were having that issue a while back with their climate control systems. They had passive IR sensors to monitor rooms/zones, but if you sat real still...

I'm selling this place as soon as I'm done building it, otherwise I'd enjoy doing something more advanced.

It's just a bunch of conditions that you don't think about normally. Like, telling it that the lighting is under a certain threshold, no movement for x number of minutes, and it is after 10 assume I'm alseep and go cold doesn't work because what if I'm watching a movie? A condition then has to be written that if the lights are below a certain threshold but are not steady to say 'he's watching a movie'. Maybe I could have it post that stuff to twitter! :rolleyes:

I have, however, thought of using Zigbee wireless to allow all my DIY stuff to talk to each other so it would be able to ask if the AV reciever is on and get a yes or no back. No assumptions.

If you're selling the house... forget my DIY damper idea lol

I have a motion sensing lighting algorithm that uses two modes, one for short stays (passing through or popping in to get something) and one for longer stays. It's a learning system, so I just use two sets of variables, one for each scenario. If it fails by turning off the light too soon or you've just been in the room for a fair bit it goes into the long term mode. I tested it in a simulator I wrote and it works quite well. Writing the simulator was surprisingly hard as I realized I had no idea what my moving around behaviours actually were. Used a non-uniform random number generator with a bell curve distribution for the time between motions (I'd written it for another project).

Decided to do the return manifold first, since screw-ups will be less noticeable on it. Drilling the pipe after welding is impractical, owing to the small size of my drill press. The good news is the 3/4" nipple is quite a bit larger than 3/4" inside, so I can center it over a 3/4" hole pretty easily. Just grinding a flat the width of my grinding wheel allows the nipple half to be clamped to the 1.5" pipe in my vise with no trouble and welding it was straightforward, though it took two passes to get it leak free. Leak testing will be harder with the holes all drilled (doing them before any nipples are attached is easiest for me), but what can you do?

hot glue into the drilled holes could plug them enough to do your leak testing and should be easily removable if you don't over do it.

I have some 3/4" threaded caps already so I'm just going to weld all the nipples on and test them all at once. I also have two 1.5" to 3/4" adapters (one for each manifold) so I can do the same trick on both pipe ends. Should get the job done. Thanks, though. It only needs to be tested to about 20 psi, so that'd probably have worked fine.

Wait a second! I have some washer hoses I used to have my air handler attached with. Since there are four nipples I can hook them together in pairs to seal 'em. No pipe dope or teflon tape needed. Nice. :D

Got the return manifold done. My pressure testing setup is rather amusing looking but works fine. I noticed that each successive weld was less leaky, but only the last one was airtight right off the bat. In future, I should practice welding on some scrap before diving in if it's been a while since I've welded.

https://www.fuelly.com/attachments/fo...284ed96760.jpg

To correct the nipple alignment problems I had with the return manifold (where it doesn't really matter) when making the supply one (where it does), I drilled the holes before any welding, made a paper template of the curved ends the nipples should have to improve grinding, and made a piece of dowel on my lathe to align the nipples. Had to wrap the ends of it with masking tape as the hole diameter is slightly smaller than the nipple inside diameter. If I'd thought of it I guess I could've left one end the larger size and only wrapped one side. Rats. I only tacked them in place before removing the dowel so it wouldn't catch on fire. They came out nice and straight. Just need to pressure test and this project is done. I'm resisting the urge to redo the return one.