I have a design in mind for a closed loop heating element but wish not to use any bearings. Design simple, tube inside tube, say one inch spacing, half inch diameter magnetic impeller, fluid will fill rest of cavity. Both ends simply capped. Magnetic driveshaft is placed inside donut hole to spin impeller. Low rpm. How can one keep impeller centered without bearings. Spindles is my only answer which is poor. Impeller possibly may not need any centering device but would be a surprise. Closed loop heating element will attain 240degF so I believe bearings are a solution I just do not want to use them to create the longest possible worklife of heating element. Be thankfull for any replies.