Question

A room is heated with a 1500 W electric heater. How much power can be saved if a heat pump with a COP of 2 is used instead ?

• A. 0 W
• B. 1500 W
• C. 750 W
• D. 375 W

Answer 1

The correct option is C 750 W

Assume the heat pump has to deliver 1500 W as heating effect (HE)

$(COP{)}_{HP}=\frac{HE}{W_{input}}$

$2=\frac{1500}{W_{input}}$

$W_{input}=750W$

So the heat pump requires an input of 750 W thus saving the difference,

$W_{saved}=1500W-750W=750W$