This really depends on what size your living room is and how much heat output you require from each radiator in order to keep it comfortably warm throughout the winter months. Generally speaking, one to two radiators should provide sufficient heating for most average-sized living rooms. However, this number can vary depending on factors such as ceiling height and insulation levels within your house so a btu calculator can help you to work out how many radiators you need. It's always best practice to consult with an expert before installing any new radiators. They can ensure you have sufficient coverage for your entire living room area and advise on which type of radiator will best suit your needs.