An electric heater to heat a flow of a fluid having a jacket block comprising a plurality of longitudinal bores to allow the through-flow of a gas phase medium. An elongate heating element extends through each of the bores that together with the jacket block define a heating assembly to heat the gas. The heating assembly is positionally stabilised within the electric heater via at least one brace configured to inhibit undesirable independent axial and/or lateral movement of the heating assembly within the electric heater.