pjb, Sometimes you cannot avoid them though. I know someone who was turning on his faucet and got bit. Someone I used to work with was doing laundry inside her home and reached down to get some clothes and got bit, they figure it came through the dog door. I went to turn the lights off in my garage one evening and turned the corner in my hallway and there was one (I didn't get bit). Several species of rattlesnake will give you the chance to retreat but some like the Mojave green are just plain nasty. In the 20 years we've lived here I have dispatched more rattlers than I care to think about. My 4yr old g-son was less than 1/2 ft from one. Luckily it was injesting and couldn't strike. DH was weeding one winter and touched the back of one- thank God it was lethargic from the cold. I went to get a sweater one night (7/4) from DH's truck- stepped down and heard a rattle. I had to wait in the dark until it rattled again and then I jumped the other way. That was a 3' diamondback- it was less than a foot away. BTW, that 2 year old I posted about last month. The child is Dr. Sean Bush's little boy. Dr Bush who lives about 1/2 mile from us is the ponytail venom doctor from the TV channel Animal Planet's "Venom ER" show. Jude saw the snake in their backyard and tried to pick it up. Dr Bush keeps snakes, spiders, scorpians etc in his garage (well contained) and Jude thinking this was one of his daddy's snakes that got loose wanted to help. If you ever got bit Dr Bush is the man you want to take care of you. In fact he is on call if President Bush (no relation) ever gets bit at his ranch in Crawford.

Do you have AC? Do you want it? Consider talking with a local building expert or independent energy rater. In my location, the advice would be to seal the attic and spray-foam insulate the roof deck to keep your duct leaks inside the living space. I live, however, in the humid Gulf South. I don�t know if that is advisable where you live. Heat gains into the attic and into the ducts are mostly radiant, anywhere. Here, the spray foam greatly reduces air infiltration along with the moisture that comes with it reducing AC load. A radiant barrier will not approach the savings. I include that detail to illustrate the kind of thinking that needs to be done. Michigan will be different. That is why you need a GOOD local energy rater. You are contemplating drastic changes to your home. They can help you identity the most cost-effective ways to improve your home in addition to the HVAC system. There are sometimes programs that subsidize the cost of evaluation. Will a heat pump work or is it too cold? Can a high-velocity, forced-air heating system be installed as sleeves in your current ducts? (The ground has a pretty moderate temperature compared to your current attic.) Could you snake hydronic heating pipes (PEX) though your current decrepit ducts and use them to feed radiators in the rooms? That would be sweet if you only need heat. If you want AC, consider mini-splits. Heat pump, mini-splits could provide heat when the temps are moderate and you can use the hydronic for the coldest weather.

Looking at the design, I see a basic design bastardized. The various runs will move air, but probably not enough air to all areas. IMO it can be balanced, but will need rebalancing every season, in the present design, until you give up and just suffer. For instance the air into the den looks to be less what is needed?? When designing a spider system, care in sizing branches is important. If they are the wrong size, not enough air will move thru them to the extremities. The system needs way to many dampers, that need adjustment during rough in. Depending on the heights of the various rooms, this might be the best that can be done without spending a LOT of money. On the otherhand, it sure looks dumb on paper. Returns are important in making a duct system work, and there are not enough returns in this design. Forget the inlet area for now, the locaztions of the returns will make balancing very difficult. Although flex is considered a good duct material, I do not want anything plastic in my attic. Either I will crush it doing a repair, or it will melt in the heat. The one positive about plastic is when it is snaked thru the attic, the very design of it allows maximum air flow without excessive turbulance, which results in lower system. static pressure. As to the design, I don't like to use duct less than 6 inch diameter for a run longer than 4 feet. The smaller diameters restrict air too much. Although they are right for small rooms, the rooms never seem to get enough air. If it is at the end of a run, the air is again not enough.

Thanks guys. Let me see if I can provide a clearer picture of what I'm working with. The house is over 100 years old--a brick row house in the center of a block. Most walls and all the ceilings on the third floor are plaster, with lots of lumps and bumps and a few small cracks, but mostly solid. There are no ceiling moldings. To call what is above this floor an attic is a an exaggeration. It is a space that ranges from about 3 foot tall at the front of the house to about half that at the back of the house (roughly 40-feet on that floor...first and second floors have a bigger footprint and do not need insulating between living space and roof.) There is a central air (newish high-velocity, narrow tube) system that snakes around the "attic". The blower is installed at the one access point there had been. This system serves ONLY the third floor and has two outlets in each of three small bedrooms and one in the tiny bathroom. The system serving the first and second floors is in a second floor closet. The insulation guys tell me that they can blow insulation in but will need to cut at least one new mansized hole in the ceiling to get in--possibly two, one toward either end. There are no recessed lights on the floor, and only three overhead lights at all. All other lights are wall brackets, wired from the floor up, rather than from the ceiling down. Of the three overheads..one was put in new by me, so isn't K&T. One the previous owner says was moved by them, so isn't K&T (But may connect in to K&T at the meeting of wall and ceiling. And one is the bathroom overhead, which can easily be checked. My electrician replaced the fixture there, so he should know what's above it. The roof is asphalt and fairly new (say 5 years old?) so, I'm not inclined to want to replace it anytime soon. I've gotten a quote for $950 to cut an access whole and blow in insulation. I'd have to pay someone else separately to fix up the access panel afterwards, probably adding another few hundred. Most neighbors don't even try to do much of anything with ventilation in their "attics", as they are all scared witless of cutting holes in their roofs. But I have found info on the Brooklyn Brownstoner blog about successful attic and whole house fan installations and one neighbor loves the whole house fan he has which sits in a sort of plastic cove on the roof. Unfortunately, he bought it with the house and has no idea who installed it. I don't intend to move in the near future, or even the more distant future. But I would like to make the third floor more habitable in the summer, especially since at some point in the next two years or so, I'd like to turn it into a separate apartment and rent it. Honestly, I seem to be finding such conflicting information and I'm so dubious about how knowledgeable folks you hire to do this stuff are about old and "out of the norm" houses that I really, really, do appreciate any and all help I can get here on this forum. Thanks,