

@viertesauge
They’re inefficient and costly compared to simple resistive heat. If you need to heat inexpensively and simply, resistive heating elements are impossible to beat. If you need to heat (and cool) efficiently, then a refrigerant based heat pump can’t be beat.
Don’t let the “heat pump” label of peltier units fool you. These aren’t like the heat pumps that use phase change of a refrigerant to be efficient. They’re just heat pumps because they cool one side while heating the other (and can reverse that effect). A phase change heat pump is far more efficient.
The only practical applications of peltier systems are where space is an important factor and solid state operation is a deciding advantage (though fans are often integrated in systems not using heat pipes or liquid heat transfer).


@viertesauge
Using the same amount of energy input, a resistive heater will output more heat.