If it is not possible to connect the heater to the heating system, similar heaters equipped with electric heaters can be used. An example is the zehnder group of bathroom radiators, the selected types of which are shown in the following figures

Mounting and power supply of Zehnder-Toga II radiators (dimensions in mm), Marks: With – power supply, P – return, THE – electrical network

Toga II type radiators are made of D-shaped pipes. The figure shows the details of fixing and powering the radiators in question, and the table lists selected data.

Technical data of ladder heaters type Zendher -Toga II

A large number of their varieties are available. In order to increase the heat dissipation surface of tubular radiators, they are ribbed. This ribbing can be made of flat tape (so-called. coopers), smooth or corrugated, or from single discs (as was the case in the formerly used ribbed steel pipes). The main condition for obtaining the desired increase in heat transfer is to ensure good contact of the pipes with the ribs and frequent cleaning of the intercostal surfaces. These heaters can be divided depending on the number of wires set into one- (GŻ-1), two- (GŻ-2), three- (GŻ-3) and four-row (GŻ-4), and depending on the length of the ribbed parts, one can distinguish 11 Types.

Technical data of the GŻ-2 radiator (dimensions in mm), Marks: 1 – stiffening BI 65x8x220,2 – connection connection

The figure shows a diagram of the GŻ-2 radiator along with the characteristic dimensions. GŻ radiators are made of smooth pipes (0 76×3 Mm), with round or rectangular ribs. As for radiators from smooth wires, also for heaters made of finned tubes it is possible to simplify the determination of the heat transfer coefficient. The coefficient a has a value variable from 1,0 (for a radiator with one row), by means of 0,94 (with two rows) into 0,91 (with three or four rows). The table lists the thermal performance of radiators ribbed with steel strip.

Thermal performance of selected ribbed radiators GŻ