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Check these ones out.

http://www.builditsolar.com/References/Calculators/HeatLoss/HeatLoss.htm

 

http://www.alternateheatingsystems.com/btucalculatorheatlosscalculator.htm

 

http://hlc.warmlyyours.com/room/room_general

 

This one actually has an option to calculate using Unico or a conventional hot air/baseboard heating method.

http://www.heatload.com/