Danfoss recommend that the valve gland seal also be replaced as part of any upgrade. The Danfoss Randall Gland Seal for RAV/RAVL 013U007000 is a gland seal assembly for RAV and RAVL valves, these can be replaced without draining down the system.
Can be replaced without draining the system
Technical specification
Waist Sizeaa88cg38guTypeParts & AccessoriesSupplier Part Number013G029000Range DescriptionTRV accessoriesBrand NameDanfoss