I know that bronze pumps are normally specified for DHW secondary circulation, but I recently noticed that what look that normal domestic heating pumps with plastic bodies are sometimes used for the secondary circulation on storage combis - e.g. the Saunier Duval Isomax.
Can anyone think of any reason why a plastic bodied heating pump shouldn't be used instead of an expensive bronze bodied DHW pump for a regular secondary circulation? If the bearings are ceramic (Grundfos?) and the shaft, can and rotor are enclosed in stainless steel, is there anything that could corrode?
Can anyone think of any reason why a plastic bodied heating pump shouldn't be used instead of an expensive bronze bodied DHW pump for a regular secondary circulation? If the bearings are ceramic (Grundfos?) and the shaft, can and rotor are enclosed in stainless steel, is there anything that could corrode?