If compact radiators are housed in a box, there must be sufficient openings at the top and bottom. Baseboard units which are recessed into the wall should have plenty of vents at floor level and along the top of the housing. Aesthetically designed cabinets used to enclose old fashioned free-standing radiators should also be built with plenty of holes.
Always leave a space of at least twelve centimeters between the heating unit and any upholstered or wooden furniture in front of it. Never hang curtains or drapes too close. The old style compact radiators are constructed with several sections that allow the air to flow through and around them. The cast iron stores the heat for some time, and will continue heating the room for a good while after the boiler has turned off. But, they can also take longer to heat up. Contemporary compact radiators can have a high number of steel fins welded to the outside of the pipes that carry the hot water from the boiler.
When these fins get heated, they emit warmth into the air flowing around them so that the current of warm air begins its convection almost as soon as the heat arrives in the unit. Because the efficient dispersal of heat depends on air circulation it is crucial for compact radiators to be cleaned regularly. Layers of dust or lint should never be allowed to accumulate as these not only keep air from moving freely, they also act as insulation that slows the transmission of heat.