Daikin RXYQ5PY1 Service Manual page 206

R-410a heat pump 50hz/60hz cooling only 50hz
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Appendix
7.14.6 Example 6: Cracks Develop in Field Pipes due to Thermal Expansion
and Contraction
Situation
Refrigerant piping has developed cracks in soldered points and is leaking gas.
Cause
Both ends of the pipe have been tightly fixed in place.
Starting and stopping the compressor has caused temperature to vary, thus the pipes have
expanded and contracted which places stress on soldered parts.
Cracks have formed because of repeated expansion and contraction.
Remedial Action
Fit the pipe with a loop as shown in the below drawing.
Main Points
! Take thermal expansion and contraction along the spline into consideration when installing
For Your
Expansion (m) = Full length × Coefficient of thermal expansion × Rise in temperature
Coefficient of thermal expansion for copper: 16.5 × 10
Reference
Example For a pipe length of 10 m and a rise in temperature of 50°C, expansion reaches
200
Tightly fixed
Cracks developed here
in soldered parts
Tightly fixed
Before remedial action
pipe supports.
8.2 mm.
Absorb expansion
with loop.
After remedial action
-6
General Information
SiEN34-705
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