My parents currently have an un-vented, natural-gas fired, open flame (!) space heater installed in a sunroom/porch off of their dining room. For obvious reasons, I would like to buy them a direct vent space heater that draws outside air for combustion. The room is small (~200 sq. ft.), and I would really appreciate it if someone could recommend a good name-brand heater. They don't see any problem with the heater they have now (they are old and stubborn!), so I will have to buy it for them and ship it to them, but I really don't know much about this or what companies manufacture the best product. Advice would really be appreciated.