First off-great forum! Glad I found this place! My wife and I bought our 700 SF single story 2 bedroom/1 bathroom ranch with attached garage in Northwestern NJ a little over three years ago. We just finished the basement which gave us an extra 400 SF of living space in the form of a family room, but we'll need more room soon. We knew we would either have to add on or move one day since we are hoping to have three children (our first is due this September ) eventually, so with the housing market being what it is, I think it would be wise to plan for an addition in the next 4-5 years. Basically we need one more full bath and one more bedroom for a total of three bedrooms and two full baths. The addition I've sketched out will simply be a 15' x 26' box tacked onto the rear of our existing home. This will provide the space for two new bedrooms. One of the existing bedrooms will be divided into space for a hallway to access the two new bedrooms, and a full bath connected to the master bedroom. I've been fooling around with ideas in Google Sketchup (amazing tool considering it's a free download) and made up a graphic to illustrate the existing house vs. the planned addition:

The blue walls are the existing walls of the home so you can pretty much tell what the original building envelope looks like. The pink walls represent the planned new construction. The grey walls represent the present bedroom which will be cut up into a hallway and a master bathroom. I realize this isn't a DIY construction site, but I figured that some background would be helpful. Right now the home has a 6 year old forced air oil furnace which we supplement with an add-on wood furnace which is integrated into the existing ductwork. We like heating with wood, and provide most of our heat this way, burning five cords or so per winter, but we hate the forced air heat. There are lots of cold spots in the house no matter what we do, and the dryness is just awful in the dead of winter. In any event, we want to be rid of it when we renovate. I will be doing a lot of the work myself-my FIL is in the construction industry and will be serving as my adviser for the entire project. He will get me subs for the excavation, foundation (there will be a full basement under the addition), and electrical, but the rest we'll be doing ourselves/with the help of a few laborers. Basically I'm trying to get an idea of what skills, tools, etc...I need to install an oil boiler myself.

First, obviously I'm starting from scratch as there is no existing infrastructure for hot water heat. Part of what always made me leery of hot water heat was sweating copper and working with rigid pipe in general. Despite a lot of DIY experience this was something I never quite mastered. Lately though I've been reading a lot about PEX and it's applications in hot water heating. I also happened to see an episode of "Ask This Old House" where they used PEX to add a zone to an existing hot water heat system and it looked fairly straightforward. Is installing a boiler these days really as easy as running attaching PEX to each zone valve, snaking it up to the appropriate baseboard, and then doing the same to bring it back to the cold side of the boiler? I'm hoping so since working with flexible PEX would be a lot easier than cutting copper pipe, sweating elbows, etc... I have the basic idea of how a boiler works down, but one thing I know nothing about is sizing baseboards for a room-can anyone tell me what a good installation would look like in house like mine? I know that I need to do a heat loss calculation to size the boiler, but I have no idea how much baseboard an 11 x 14 bedroom or an 8 x 11 bathroom needs. Any help or guidance will be greatly appreciated!