Diagnosing Fouled Coax

Discussion in 'Maintenance and Troubleshooting' started by geoxne, Sep 3, 2014.

  1. geoxne

    geoxne Active Member Forum Leader

    I understand the proper procedure for measuring DeltaP across the coil and looking up the corresponding flow rate in the manufacturers tables. If a coil is fouled wouldn't the DeltaP rise giving a false indication of proper or overflow?

    In such a case what other symptoms have to be measured to confirm fouling?
  2. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

    The saturated suction refrigerant temperature would become lower.
  3. Bergy

    Bergy Member Industry Professional Forum Leader

    Heat Exchanger Scaling Calculations

    Here is the formula for measuring scale build up through the coax. Diluted Ice machine cleaning fluid is recommended.
    Heating mode: Evaporator HX TD = avg. fluid temperature – evaporator temperature
    Cooling mode: Condenser HX TD = condenser temperature – avg. fluid temperature
    Evaporator temp is suction saturation temp
    Condenser temp is discharge saturation temp
    A result of 5-15F is normal (over 20 suspect scaling)
    Ice machine cleaning fluid should be used to flush the heat exchanger. This process can take time depending on the build up of calcium. The fluid will come out chalky and if the return hose is placed next to the wall of the bucket a faint copper deposit will be noted when all the calcium is removed. Be sure to flush with clean water before putting back into service.

    Example: (Heating mode)
    EWT = 50°F, LWT = 45°F; Suction press = 95psi
    Average Fluid Temperature = (50°F + 45°F) ÷ 2 = 47.5°F
    Evaporator Saturation Temperature = 29°F (look up on P/T)
    Evaporator HX TD = 47.5°F - 29°F = 18.5°F
    Efficiency is marginal, probably needs cleaning.
    (Enertech Mfg.)


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