The idea of integrating a temperature controller directly on the relevant heating system failed in the past due to the size of the components. Today's SMD technology only takes up a fraction of the space of earlier electronics. This prompted us to develop a complete temperature controller for installation in the upper part of the PA hard cap of our heating hoses. The HT 54 is the result! We have accommodated the controller board on an area of just 35 x 40 mm. Thanks to this construction, the customer can save on external control devices. This creates space in the switchgear cabinet. The HT 54 can also be used just as well for control purposes on heating jacket heating plates or heating strips. Its small dimensions open up new fields of application.