Alongside a properly prepared flare, ensuring proper tightening of flare nuts is critical to ensuring a leak-free installation. Under-tightening may result in a leaky partial seal, whereas overtightening can damage or even crack the flare nut. An accurate torque wrench takes the guesswork out of this important step.
Hazet make great quality torque wrenches and the kit includes their 10-60Nm model. It comes with crows-foot adapters to fit the common flare nut sizes. Check your AC unit installation manual for specific torque recommendations.
As an example, Bosch recommend these tightening torques for their rebadged Midea units:
- 18-20Nm for 1/4" pipe
- 32-39Nm for 3/8" pipe
- 49-59Nm for 1/2" pipe