Tubing & brazing: General tips

Short, practical technician tips on tubing & brazing for general. Check each one against the manual for your exact model before acting.

Elbows

Generic

Long-radius or vaned elbows; air crowds the outside of a bend and gets turbulent.

Fan noise fixes

Generic

Rattle = tighten setscrew; press-fit hub loose = replace blade; bent/vibrating blades = replace, don't balance in the field; blades hitting shroud = move fan on shaft or move housing, never bend blades.

One-pipe vs two-pipe oil

Generic

One-pipe: half the tubing, less copper-sludge, but must be bled; two-pipe: self-priming, but pumps ~15 gal per gal burned and a pressurized return leak goes unnoticed.

Round duct orientation

Generic

Crimped end points in direction of airflow; screw through the overlap; mastic the joint. Starting collar tabs bend inside plenum.