Actuator means and heating system

摘要

Actuator means (12) for a heat exchanger valve are described, said actuator means (12) comprising a thermally expandable medium (22) in a closed volume (21) acting on a plunger (25), heating means (23) for heating said medium (22) and control means controlling said heating means (23). The construction of said actuator means should be kept simple. To this end said heating means (23) has a temperature depending electrical resistance value and said control means uses said resistance value for determining a stroke of said plunger (25).