t33.grtactical

Replacement impeller for all Kestrel Meters. User replaceable.

Impeller Replacement Instructions

Using your thumbs, press FIRMLY on the impeller module to remove the entire unit. Press only the sides of the new impeller  when installing to avoid damaging the precision hub bearing.  Insert the impeller so that the half that has the serial number label on it goes in first and faces the back of the unit once in place.  Orient  one "arm' straight up (The impeller should look like a peace symbol or  an upside-down Y).

My impeller is making a rattling/clicking/whirring noise, is that normal?

It is common for the Kestrel to make a rattling noise with a wind speed from 5 to 10 miles per hour. This is completely normal and  accurate.

To better understand why the impeller rattles, one needs to  know what is inside. Inside the plastic housing, there are four separate parts. The fan, two sapphire jewel bearings and a metal pin. The fan  rotates around the metal pin which is held in the plastic housing by the jewel bearings. For the fan to move freely (to not cause excess  friction) there is a small space (on either side) between the end of the metal pin and the jewel bearing. The space between the metal pin and  the jewel bearing is what causes the rattle. Some impellers can be  louder that others, but the accuracy will be the same.