Grundfos reciculating pump

Oct 29, 2005 4 Replies

I have a cast iron pump that is only two years old and when I went to use it today it got warm but didn't ciculate any water. Is there a way to repair the pump? I had one of these that lasted years in my old house why would this one fail after such a short time?



Thanks for any help, Rich


I had the same issue with solar pump. Old one lasted a long time then I replaced it and the new one crapped, fortunely for me with in the warranty period. I replaced it with one with slightly more head pressure and never had another problem. All new stuff is slightly less good than the stuff from 10 years ago. I have made it practice to research and check the specs on everything that I work on now days.

To my knowledge repair is not practical. Take it out of service and look at the impeller. Is there anything in there that is a problem?

Air in the water can destroy a cast iron pump from corrosion and cavitation. If the rotor is locked from corrosion, you can take it apart to replace the rotor, but sometimes it's just easier to swap it out for a new one. Make sure you have a Spiro-vent or similar de-airing fitting in the lines.

Could be a lot of things. Seals, bearings, corrosion, impoper assembly, something out of spec, etc. Grundfos makes very good p umps, but like any manufactured product, they will eventually wear or brak or just be less than perfect from the start.

If it's actually cast iron on your domestic hot water, the impeller is eaten away. There's too much dissolved oxygen in domestic (as opposed to heating water) to have a cast iron impeller.

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