The disadvantages include a high price, demand for large surface area and high steel consumption. Such heaters can be used in rooms with low thermal needs, on the lower floors of staircases (especially at the main entrance doors to tall buildings) or when, for hygienic reasons, it is not advisable to use ribbed radiators. They are now rarely used, and the exception is auxiliary rooms in buildings, for example. warehouses, Cellars, Dryers, e.t.c. In ladder versions they are willingly used in bathrooms, due to the possibility of their use as a dryer for towels or linen. These radiators have different shapes and are constructed from pipes with small diameters, corrosion protected. The most common solution is to connect horizontal tubes with collectors by welding. The main collector is closed with an external weld from the wall side and is invisible to the user. In some cases, welded or soldered copper tubes are also used. Laser technology is also used. External surfaces are coated with powder paint and then subjected to the firing process at a temperature of +180-230°C, resulting in a smooth surface without stains and easy to maintain cleanliness. There are also radiators with chrome surfaces and unusual shapes. Such solutions are more expensive than varnished ones by about 50%, and the heat emission is slightly lower. They are usually made of steel pipes with a diameter 18 mm and steel sections 30×30 mm or 40×40 Mm. They have performance 100-130 W with a maximum heating water temperature of up to + 95 ° C and an operating pressure of up to 0,6 MPa.

The table summarizes the design and operational parameters of smooth bathroom radiators cooperating with the heating system for the most common parameters. There are a large number of this type of heaters of any shape and color (approx 100 types of paints).