I have a Buderus Oil Boiler with the logamatic controller. It's used in a four story apartment building and it provides for DHW. There is a loop (that's what i call it...) that provides constant hot water to the apartments. In this loop is where I replaced the circulator because it was making a loud noise and it wasn't providing on demand hot water to the faucets and baths. I replaced it with the correct cartridge and I can hear it and feel it when it runs, but there is no hot water going through it. The pipe coming from the hot water tank to the circulator is always either luke warm or cold.
I think it must be the logomatic controller or something. maybe it reset when when the old went bad or when I replaced it? Any ideas or advice?