I've seen similar ads.
Despite what they say about it heating a whole house, it is still just a
1500 watt space heater and won't produce more heat than any other. Any
big-box store will sell you 10 small heaters for that price.
The heater is free, it's just that first you have to buy the $300
cabinet made by proud Amish craftsmen, first. Notice this unit comes
with a moneyback several year guarantee. That means the cabinet is
warranteed and the heater itself was just something they threw in free.