Stelrad Vita Silhouette K1 radiator 600 x 600mm

Flat panel radiators are steel panel radiators with a flat, smooth front face. They connect to a wet central heating system in the same way as other panel radiators and are made in horizontal and vertical formats, in a range of heights and lengths, as single or double panel types.

Panel types

• Type 11 (K1): a single panel with one set of convector fins; the slimmest type.
• Type 22 (K2): two panels with two sets of fins. It gives more heat than a single panel of the same height and length, but is deeper, so it stands further from the wall.

Heat output

Radiator outputs are tested to BS EN 442 so that products can be compared on the same basis. Figures are quoted in watts, or BTU per hour (1 watt is about 3.41 BTU per hour), at Delta T50: a mean water temperature 50°C above a room at 20°C, based on 75°C flow and 65°C return. Systems that run cooler, such as heat pumps, give less heat from the same radiator, so check the output at your system's actual Delta T.

Sizing and controls

Work out the heat loss of the room, then choose a radiator, or radiators, whose output at your system's operating temperature covers it and whose size fits the wall space. Check where the pipes will run and which valves you need. In England, when a boiler is installed or replaced, Approved Document L expects thermostatic radiator valves on each radiator except those in the room with the main room thermostat.

To control each room, see thermostatic radiator valves, or browse radiator accessories.