Heating circulation thermostats are specially designed for temperature control of externally attached applications with a small volume. The units are fitted with bath tanks made of transparent polycarbonate. The thermostats have M16x1 pump connections at the rear side as well as a stainless steel bath cover with a filling opening. All models are fitted with an overtemperature and low level protection system according to safety class III/FL (DIN 12876) for use with flammable fluids. A powerful circulation pump ensures optimal heat transfer to external attached applications.