Radiators are used in either steam or hot water systems. They are usually seen only in older homes. Steam radiators look the same as hot water radiators except there is a steam check valve on them. This valve allows air out of the radiator when steam comes in and closes to prevent the steam from escaping. The inspector checks these radiators carefully because they can be prone to air binding, leaks and bad valves. Converting radiator systems to baseboard systems can be much more expensive than anticipated depending on the original piping installation.