Gary and I started putting in the pipe for the heating system yesterday. When planning the house we settled on in-floor radient heat on a boiler system. So far it has been a large learning curve, not only for us but it also for the first mechanical contractor. Smokin’ Joe wasn’t much on new things, and had difficulty thinking that some of the components of the system we have would actually work. Smokin’ Joe probably deserves his own post, or several. Remind me to tell you about the four way valve. And the dentures.
Essentially, with our system pipe gets strung in the floor joists between the first and second floor, and between a subfloor and a sub-subfloor on the main floor. For all intents and purposes it turns your floors into large radiators. 
But it takes alot of pipe. Pretty much over 1700 metres in our house, that’s over a mile of hose.
The pipe is a 1/2 inch plastic pipe that comes in 1000 and 300 foot rolls. Ideally, as we found out later, one uses a large specially designed reel to feed the house and prevent it from twisting. As we didn’t have one, we had to literally stand over the roll of hose and spin it by hand while the other payed out hose.
The pipe gets attached to the underside of the floor with thin metal heat transfer plates, that get stapled up into the plywood. The heat tranfer plates more evenly spread the heat from the pipe to the floor. It took us awhile but we eventually picked up on a system for installing the pipe and after tomorrow should be well on our way to getting the pipe installed in the upper floor. 
The main floor, however, will be another story as we are pretty much making it up as we go along. The method the engineers envisioned involved material (gypcrete) that we have no access to up here. We think we know what we are going to do, in order to 1)get the heat to transfer effeciently 2) attach the pipe and 3) keep the floor from squeaking. But, as they say, the proof will be in the pudding and until we actually start on it we won’t know exactly how it will install.
I can’t wait until we get at it actually. I’m starting to enjoy the mental challenges these learning curves are bringing.