Suitable pump for a DHW secondary circulation?

[chrishutt]

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?

 

[ChrisR]

Down to what's WRAS approved I imagine.
For years it's been possible to buy plastic bodies to bolt onto heating pumps for use in big fish tanks.

 

[chrishutt]

If the cost difference is the best part of £100 then I don't think anyone's going to give a fig whether WRAS approve it or not. Is there any practical reason why not? Also plastic bodied pumps can be ordered through suppliers like Antares.

 

[ChrisR]

Well the fish don't die...