jim d wrote:coal boiler w/ coils inn the ducts seoerate zones w/ anti frese use the blowersin the existing furnaces
What Jim Said!
Also I'm glad you are here asking for advice cause someone has given you some bad advice previoulsy. A 2,000 sq. ft house with two separate forced air systems? Makes no sense. And a 160000 btu unit coal heat for a 2,000 sq. ft. house also is overkill unless you have no windows.
I've been in HVAC for 30 years, and this is basically what I did. The hot water coils can be set up to have a constant trickle of hot water so they don't freeze in the attic and if they are insulated properly it won't be a problem. What I should have done was installed a wood/coal burning boiler and used that along with my oil burning boiler. I did use heat pumps, in the spring and fall they are efficient enough to be cheaper to use than coal. The reason for the coal stove is twofold: I didn't think of it during initial construction and the stove is independent of electrical power. I am working on a simple solution to use the basement mounted air handler to move the heated air in the basement up to the living space.
Two systems in a 2k sq ft house makes perfect sense to me if its a two story house. if you run one system in a two story, you'll have a warm 2nd floor under AC and and a cold first floor/basement for heating. The added cost of installation vs the improved efficiency and comfort break even at about 12 to 15 years.