The dry radiators heat up rapidly and so the response when first switched on is immediate. This is particularly apparent in the double element radiators, where the surface resistance is located immediately behind the front panel. In contrast, a wet radiator would take longer to feel warm, as the element has to heat up the fluid contained with the unit. Once the heat is built up, fluidfilled radiators have good heat retention.

Even when the thermostat cuts the supply of electricity to the element, the heat retained in the fluid continues to be radiated. A dry radiator with a cast steel block is a similar way of recreating this retention. A down side of good heat retention is the weight and dimensions. A 2000W fluidfilled, traditionally styled radiator weighs 70 kg and is 1300 mm wide; a radiator with a cast steel element of the same rating weighs 49 kg and is 1200 mm wide. In comparison, a 2000W radiator with a single aluminium element weighs a mere 10 kg, but is still 1020 mm wide. In addition, you would not get the same degree of heat retention, so the radiator would appear to heat up and cool down more.

The convector heater is a lightweight and compact unit. It would invariably be smaller and lighter than a radiator of equivalent wattage, at about 7.4 kg and 740 mm. The convector heats up rapidly, but has no heat retention. Whilst heat is felt almost immediately that the appliance is switched on, the heat travels up towards the ceiling rather than across the room. The heat reaches the occupants by circulation of air currents and conduction to the cooler air at lower levels. At a distance of 2.5 metres from the appliance the temperature difference in a room of average height can be 5°C between the floor and ceiling. With a radiator, the difference would be around 1.5°C.

The final difference is price. For a high specification 2000W radiator, you could expect to pay 600 €, a simpler single element radiator would be half of this price and an equivalent convector would cost around 100 €. However, these are average prices. You could pay more or less depending on style, specification and quality