TECHNICAL BULLETIN
Lime Build-up In Copper Tube Units
Symptoms
Noisy heater, Excessive vibration, Increase in outlet temperature, Cutting out on limit control or operating high limit.
Cause
Hard Water, Undersized or inoperable pump, Improper temperature rise through coil/heat exchanger
Effect
Temperature rise through coil/heat exchanger is too high, Water flow below recommended minimum, Obstruction in a passage of the Heat Exchanger or coil.
Solution
To keep this situation from happening you must maintain the proper temperature rise through the coil/heat exchanger of your heater. Insure that the pump is properly sized for your system. Use of a hard water pump in hard water areas. Water is considered hard if grains measure above 15 per gallon.
Notes
HW unit must maintain a temperature rise between 30-50 F degrees. DW-DB unit must maintain a temperature rise between 20-50 F degrees. GW-GB units must maintain a temperature rise between 20-40 F degrees. LW-LB units must maintain a strict 20 F degree temperature rise. A failure to maintain the proper temperature rise per manufacturer can cause excessive lime build-up and will void manufacturers warranty. If the temperature rise between the water inlet and outlet of the heater increases 5 degrees more than what it was when the hater was installed (clean), then deliming the heater is recommended.