allen key size for pump?

[steved101]

what is the best size allen key to unscrew the 4 nuts on a circulating pump? i just need to check that the impellor has not come off...

 

[WDIK]

possibley the one that fits?



usually 5mm

 

[jackthom]

My set of allen keys aren't marked with sizes but did a quick measurement with an old imperial micrometer (0.156"), multiplied by 25.4 and I'm pretty sure it's 4mm.

That's an old grundfos 15-50, yours may be different.

 

[bengasman]

there is no best size to take the head off, there is only 1 size that fits, and it is in metric.
don't bother checking if the impeller fell off, it didn't

 

[kirkgas]

grundfoss are 4mm but i have seen some that are 6mm (Dab i think)

 

[Slugbabydotcom]

4 and 6mm are most common but sometimes you wll come across one that is 5mm