The whale heater heats both, the hot water and heating this is a very proven and efficient way to keep those temperatures under control. It works on both gas and electricity and has a simple to use set of control pannels. They are separate controls with frost setting to make sure the temp does not drop. With a proven boiler that is easy to maintain with simple drain points.The whale heater heats both, the hot water and heating this is a very proven and efficient way to keep those temperatures under control. It works on both gas and electricity and has a simple to use set of control pannels. They are separate controls with frost setting to make sure the temp does not drop. With a proven boiler that is easy to maintain with simple drain points.