garage boiler to tie in with existing home oil boiler with an add on pressurized wood/coal furnace.

Hey Eric this question is for you or anybody else with pressureized boiler experience.
I am building my garage I want to add either and a large pressureized indoor boiler(royall) or pressureized outdoor boiler (royall) to heat my garage, home, and (future pool). I have a burnham oil boiler, with a pressureized logwood (yboc36) coal /wood add on boiler heating my home. I want the garage boiler to heat my home as well. Is this going to be a problem? I do not want to disconect my logwood boiler ( I want to use it when the power goes out gravity feed) Can I use a heat exchanger? or do I have to plumb the garage boiler directly to my current home setup since it is all pressureized.

Right off the bat, it's against code to put a woodburning appliance in a garage. Just so you know. You might be able to build a special boiler room that draws combustion air from the outside and be OK, but you also might want to check with your local officials before going to the extra expense.

As to the piping, you can do it either way, since everything is pressurized. If you want to run glycol in the outbuilding/OWB side of things, then you'll either need to run glycol everywhere, or use a heat exchanger. If you want to stick to plain water, then you can just hook it up directly.

I did something similar to what you are doing for a few years. I ran glycol in the wood side and water on the house side, so I used a flat plate heat exchanger to get the heat from the wood boiler into the house. It was a Royall 6150, by the way. It worked pretty well, but I think I lost some efficiency with the hx, since the hot water has to make a few circuits through the heat exchanger to get the heat out, and I know I lost some heat in the process.

With my new system I decided to go with water on both sides and pipe direct. The response time has increased dramatically, because 175-degree water is going into the top of my gas boiler, and the return is coming out of the bottom of the boiler. Greater Delta T = more efficient heat transfer is the way I understand it.

Overall, I think you're ahead to pipe direct. Either go with all glycol, or go with water and invest what you save in better insulation and maybe a heat strip in the piping that might be vulnerable to a freezup. A Royall boiler in an insulated boiler room will hold its heat long after the fire is gone, so I wouldn't worry too much about the boiler freezing up. OWBs tend to run with glycol and heat exchangers, I believe, though I'm sure you can run plain water, too.

the garage I talked about is really my work shop (detached from house located 100 ft. away), this will funtion as my work shop/ utility room, I have a seprate 2 car garage in front of my work shop area. There will be no fuels, fumes, combustiables in the area (same building) that my boiler is located in. I believe that this will pass code. I live in the mountians this will pass under the radar.

Sounds like a perfect setup to me.

Just out of curiosity, what makes a garage a garage? Is it a car-sized door? I have an attached "garage" with wood floors that I would never put anything heavier than my lawnmower on. It is, however, the perfect spot for my workshop, but lacks heat. I would love to build/install a chimney and heat it with a small woodstove. I would remove the large doors and perhaps install a 36" door or maybe a double unit if that's what it takes to make it not a "garage". Many people around here tend to disregard rules and such, and have wood/coal stoves and boilers in their garages. But I wouldn't try it with my neighbors here, they tend to notice major changes, like if I up the wattage in my porch light and other earth-shattering changes.

I think if you can park a car in it, i.e. if it has a garage door, then it's considered a garage. Of course, you can park a car, and any number of other machines, in a barn, which I don't think is considered a garage.

But I would also say that a barn would not be attached to the house in any circumstance. Ergo, any non-attached appurtanance with farm machinery parked in it is a barn? Wouldn't that be a machine shed? A barn seems to indicate the current or past occupance by animals. My head hurts.

I used to work with our local inspector, I'll bug him with that question. Guaranteed he'll want a week to think about it.

I have no idea, and really no great interest in finding out.