Ideally, the thermal break would be a section of tubing that had low thermal conductivity. However, to function safely, it would still need the fire resistance and strength properties of the steel that your ducting should be made of. An 11-inch diameter tube with some low conductivity fireproof fill (e.g., rock wool) supporting a small gap in the 10-inch tubing would be an example of a thermal break that was safe and strong. As it happens, the relatively thin galvanized steel used for ducting is a pretty poor thermal conductor, and so long as a reasonable section is insulated on the outside where it enters a cold space, I wouldn't expect you to notice much heat loss from thermal conductivity effects. I run a 6 gph capacity centrifugal humidifier with a winter setting of 35% humidity. I do not see any moisture from condensation dripping down inside my Wolf hood with 10-inch ducting. The duct on the other side is in an unheated, well ventilated attic. There is about 20-inches of insulation there. However, the temperature has only reached 4F around here, and is generally warmer, so more extreme weather conditions might lead to different results. However, with your ducting entering a garage, which even if not heated will somewhat temper the air temperature, I would doubt that a thermal break would yield any measurable advantage. kas

missylin, when we needed to gut our bathroom, we hadn't done anything like that before, had just moved here 2 years before and really didn't know of any one we could get a referral from. We were also on a limited budget. Originally, I was going to General Contract the project myself and hire out each phase. While looking at tile, I asked the salesman if they had anyone they could refer for tile. They gave me a list and I called a couple for quotes. Each time I asked if they knew of a reputable plumber or carpenter. Once I got the plumber, he recommended his friend, a carpenter who happened to be a General Contractor. It was a timely process but in the end, the General Contractor gave us a turn key quote that was really reasonable so we went that route. He used the same plumber and so far we've been really happy with the results. I will never use a Handyman again, that turned out to be a big disaster. He thought he knew everything, but knew very little in the end, and his work was sloppy to boot. We're even going to have 5 doors that he installed redone by the new GC. I don't know what area you're in, and how available help is, but you may want to give that method a try, it worked out really well for us. Good luck to you! -- Lukki

I believe that if there are two dampers in series, such as the Fantech roof device you linked to and the damper at the hood, wind gusts across the roof will have a difficult time causing both to lift together. Further, the roof vent seems to be particularly resistant to wind flowing up the roof. Spring loaded may be needed if there is significant occurrence of wind blowing in windows such as to pressurize the house higher than the area of the roof where the roof vent is located. This can happen in particularly gusty conditions when the wind faces windows on the opposite side of the house from the roof surface that the roof vent is mounted on, but then the windows might be expected to be closed. The HVAC company seems a bit cavalier. I'm not a duct expert, but I believe the requirement for hood exhaust ducts is that any grease collected flow down and remain in the duct. This requires that the higher duct fit INTO the lower duct. It is possible with a cold attic and long duct run to condense water on the duct walls. This water can drip back down into the hood. Running the fan for some time after boiling down syrup or whatever should clear the duct well enough, and the lower damper will keep humidified internal air from rising in the duct and condensing when the fan isn't running. Generally, condensation to the point of water flow should be very rare, and if the ducts are connected correctly, the worst that happens is that the water drips end up in the baffles. kas

Sorry, I didn't see your comment until now - better 2 years late than never. My plumber installed an Aqua Pure filter about 20 years ago and I've never had a problem with it. If you haven't already installed something, try looking at their 102T or 141T models. There are other equally good brands though - my current water treatment company uses Big Blue. The most important thing is to choose the replacement cartridge that you want to use and then choose the appropriate assembly to go with it. Small carbon filters can be very slow (the first one I installed was 3 gpm), so you'll want a bigger one with a high flow rate if you're filtering the water for your entire house. I currently use an Aqua Pure AP817 filter which has a 10gpm flow rate. It works well, but it's pricey (about $32.50 through Amazon Subscribe & Save).