EVAPORATOR COIL FAILURES

1
EVAPORATOR COIL FAILURES

• Evaporator coil header replacement with
  distributors, a cost effective option for our
  customers.

2
SYMPTOMS OF EVAPORATOR RESTRICTIONS

• Frozen evaporator header tubing.
• Low suction pressure.
• The temperature of the line is approximately
  18 degrees, well below freezing.
• Head pressure higher than normal.
• Suction superheat higher than normal.

3
Overview of Failures

• The restrictions occur at the distribution header
  orifices beginning at the first header tube in
  line and ending with the last resulting in
  complete restriction and unit failure.
• Once the equipment fails from restrictions the
  header assembly or complete evaporator coil
  requires replacement.

Header Orifices
4
HEADER EVAPORATOR COIL REPLACEMENTS

• Replacing the header tube with a factory
  replacement part is not only expensive but will
  result in repeat failures. Replacement requires
  16 weld joints 1/8 away from the steel tube
  sheet resulting in problematic install and
  repeated refrigerant leaks.
• Replacement of the entire evaporator is more
  costly and also leaves the equipment prone to
  repeat failure as the header orifices will most
  likely again become restricted.
• Theses issues are a design and engineering
  problem but there is another solution which CMS
  can offer to save time, money, and is considered
  a permanent repair.

5
CMS SOLUTION

• The proposed solution is to eliminate the factory
  distribution header completely which is prone to
  failure.
• A replacement distribution header sized to
  capacity is welded in place, the step by step
  process is as follows.

NO LEAD TIME
SAVES
COOL SITE
FINAL REPAIR
6
FLOW-RATER DISTRIBUTOR INSTALLATION STEPS

• Recover refrigerant from circuit, cut liquid line
  at top of header using linesman or side cutting
  pliers.
• Cut each tube at outlet side of orifice which is
  easily located by crimp mark in tube.
• Squeeze tube with pliers to re-open, insert one
  tube from outlet side of distributor into each
  inlet tube of evaporator and braze joint.
• Pipe liquid line to each distributor, replace
  liquid line drier, weigh in charge, start unit
  and check operating pressures and superheat.

7
DISTRIBUTOR PARTS LAYOUT

• The distributors used for this repair have six
  tubes on the outlet side, the number of tubes on
  the evaporator coil will determine how many
  distributors are required.
• The distributors are equipped with a 4 ton
  orifice and can be changed to depending on
  application and tonnage of circuit.

8
SIZING DISTRIBUTOR BY TONNAGE

• A 12 ton circuit with 24 inlet tubes on coil will
  require 4 distributors with 3 ton orifices in
  each.

9
THE END RESULT INSTALLED

• Once completed the unit was running with 68 PSI
  suction pressure, 270 head pressure, and 20
  degree suction superheat from previous.

10
IN CONCLUSION

• The cost in parts was a fraction of a factory
  header or coil and is a permanent repair, and
  restrictions in this system simply requires
  cleaning of the piston flow rater.
• Install time for a 12.5 ton circuit was 6 hours
  with refrigerant recovery, travel, and 1 hour of
  piping work.