They can be classified either by the type of energy used to produce the heat, like electricity, oil, gas, wood, coal or solar, or by the mechanism used to distribute the heat throughout the home, including hot air, hot water and steam.
(They; can be classified; either by the type of energy used to produce the heat, like electricity, oil, gas, wood, coal or solar, or by the mechanism) (the type of energy; used; to produce the heat) (the mechanism; used; to distribute the heat throughout the home, including hot air, hot water and steam)
They the type of energy the mechanism
can be classified used used
either by the type of energy used to produce the heat, like electricity, oil, gas, wood, coal or solar, or by the mechanism
to produce the heat
to distribute the heat throughout the home, including hot air, hot water and steam