Water storage options....

jebatty,
Your radiant system is about the same as my situation right now. My homemade Garn principle boiler is setting in my repair shop, (40'x48'x12'H) and is radiating most of its heat into my shop. The tank is a 1500gal milk tank that has about 1300 gal. of water storage, minusing firebox and flues. I have been firing mine about every 36hrs. I fire at 135-140 and usually raise it to 190 with a smaller wheelbarrow full of wood that is not seasoned at all. When it gets up above 30*F and boiler above 150*F, its almost to warm to work in the shop without opening a window. I have future plans to install and insulate the boiler in a separate structure before next heating season.

Thanks for explaining your storage setup, jebatty. No need to do it again in the other thread.

As a thought for heat exchangers - has anyone thought about using automotive / truck radiators or heater cores? At least the older ones are copper, fairly low cost, and are good for about 25psi of pressure, maximum, should be run at no more than 15psi... Seem like they should be able to pass a pretty high volume of water with low restriction, at least they do in a vehicle... I would think putting one near the top of the tank for the extraction loop and one near the bottom for the charge loop might be a very effective setup.

Gooserider

I had one of these in operation, worked well. It just wasn't pretty. Used a large squirrel cage fan behind an old truck radiator. I replaced it with a used unit heater, mostly because the unit heater fan took much less electricity (and it looked better).

I think he's talking about an intank water-to-water hx, Jim. I know slowzuki was talking about the same thing for basically the same reason.

My only concern is that a new truck radiator is probably mucho dinero, and I'm not sure I'd be comfortable using a used one, not knowing what it's been through.

How about cast iron?

never mind . . .