Aleksei's family purchased a new water heater that is a heat pump. After installation, Aleksei noticed that the room containing the new water heater felt cooler than the rest of the house.

What is the best explanation for why the room with the heat pump was cooler than the rest of the house?

a) Thermal energy from the water was transferred to the surrounding air.

b) The burning fuel increased the thermal energy in the air.

c) Thermal energy from the air surrounding the water heater was transferred to the water.

d) The burning fuel absorbed thermal energy from the surrounding air.

A heat pump is a device used to heat something, in this case water. Heat pump takes heat from colder object and transfers it to warmer object. This is opposite to direction of spontaneous heat transfer which from warmer to colder object.

In this problem a room got colder while water got warmer. This is due to work done by heat pump. This is what is described in correct answer c).

a) is not correct because it shows direction of spontaneous heat transfer. It also says that Aleksei’s family purchased a new water heater and in description givne in a) it would mean that water got colder.

b) is not correct because if the burning fuel increased the thermal energy in the air it would mean that this room got warmer than rest of house.

d) is not correct because burning fuel does not absorb thermal energy. It releases it.