District heating controller (AC 230 V) for use in DH substations or buildings. 100 % replacement by RVD140 which has the same dimensions and panel cut-out. 
Key data to replacement product: Room unit (QAA50.110/101) is required. 
Info: For d.h.w. applications with external heat exchangers, an RVD250 is required. Do not use the existing base as terminals are different - the 
Key data to replacement product: unit must be rewired (see Data Sheet).