I am having a peerless purefire PF-50 put in to replace an old electric boiler. Its a single zone all cast Iron radiator system. I am trying to make sure its installed correctly. I don't think the installer intends to install primary secondary but to just pull out the old system and tie in the new boiler. Is this OK or will it cause problems? The system install instructions all have diagrams of central heat plus DHW or multiple zone piping.
Picture is of old system. Return on left.