hydro air of steam boiler

grindog

I am working on a remodel and home owner is finishing the attic they are going with forced air rest of house is steam. The tin knocker is thinking about hydro air instead of a gas furnace.
The question that i have is, can i tie the hyro coil in to the boiler, below the water level with out the use of a heat exchanger? Ihave done this with baseboard in the past but I am worried that the sludgy boiler water will foul up the hydro coil and cause problems down the road. if i need a heat exchanger what type do you recomend?

ed wallace

hydro air and steam

if hydro air is going into unheated space it would be best to have a heat exchanger then you could add anti freeze to the hot water loop

grindog

anti freeze

the attic will be well insulated im worried about the boiler water fowling the coil. As usual money is an issue and HO would save by not using the heat exchanger