There are 4 types of Compact Radiator available at Mr Central Heating. Single Panel, Single Convector • Sometimes referred to as K1, Single Premium or Type 11 radiators. Double Panel, Single Convector • Also known as P+, Double Premium or Type 21 radiators. Double Panel, Double Convector • Double Panel, Double Convector radiators are also referred to as K2, Double Deluxe or Type 22 radiators. Triple Panel, Triple Convector • These are also known as K3, Triple Deluxe or Type 33 radiators The Panel is the front, ribbed facing of the radiator where the water channels are. The Convector is the part behind the panel, or between the panels that is the sheet metal zig zaging which helps draw the cold air up from below, heating it as it rises. How can I work out which size radiators I need? Our BTU Calculator tool will help you identify suitable radiators for the specific room(s) in question. As a guide, in our experience we’ve found the typical room size of the average 3 bedroomed house requires the following radiator sizes: Lounge = 1400 x 600 K2 Dining room = 1200 x 600 K2 Kitchen = 900 x 600 p+ Bedroom 1 = 1400 x 600 K1 Bedroom 2 = 1200 x 600 K1 Bedroom 3 = 900 x 600 P+ Bathroom = 600 x 600 P+