1. The problem statement, all variables and given/known data Here is the problem: An inventor claims to have developed a heat pump that provides a 180 kW heating effect for a 293 K household while only consuming 70 kW of power and using a heat source at 273 K. Can this claim be possible? 2. Relevant equations COP of heat pump = Qh/W COP of heat pump (carnot max) = Th/(Th-Tl) n (thermal efficiency) = W/Qh = 1-(Ql/Qh) n(max carnot) = 1- (Tl/Th) 3. The attempt at a solution The answer to this problem is that the claim is valid because the COP of the heat pump is less than the COP max, I just want to know can I use thermal efficiency instead of COP to see if this claim is valid?