R407C
Also known as: R-407C, HFC-407C
Short definitionA three-component HFC blend that took the place of R22 in air conditioners and chillers. It is non-flammable (A1), has a GWP of 1,774 and needs care because of a glide of up to 7 K.
R407C is rarely written into a cold room quotation; you are more likely to meet it in an old chiller or process line that you take over. Slightly more than half of it is R134a, the rest R32 and R125. Because it behaves like R22 under air-conditioning conditions, it stood in for it for years. Its oil is POE and it has no effect on ozone. In new air conditioners it has largely given way to R32, but service gas is still available.
When evaporation drops below −10 °C, both capacity and efficiency fall away quickly; it is not chosen for frozen rooms and stays in rooms above zero. In a retrofit from R22 the mineral oil is drained several times and its residue brought below 5%. Because the glide is large, the gas is taken from the cylinder as liquid. A technician who reads superheat from the bubble column is 5–7 K out and charges the system wrongly. In a chiller, freeze protection is set for the coldest point at the evaporator inlet.