Dimensioning of DH leakage protection systems

Design target:

DanTaet sizes DH leakage protection systems by Qmax (peak flow on the coldest day of the year) to the following criteria:

  • Lifetime: No component to be overloaded at Qmax
  • Comfort: Total system head loss to be maximum 1mWc (10kPa) at Qmax

Using these criteria, the maximum load of the various protection systems is as follows:

System \ ΔT Dim. qt (m³/h) 15°C 20°C 25°C 30°C 35°C 40°C
FBU ½" 0.8 14 kW 19 kW 23 kW 28 kW 33 kW 37 kW
FXU ¾" 1.43 25 kW 33 kW 41 kW 50 kW 58 kW 66 kW
KMP-F2,5-M2 ¾" 1.43 25 kW 33 kW 41 kW 50 kW 58 kW 66 kW
KMP-F3,5-M2 1" 2.32 40 kW 54 kW 68 kW 81 kW 94 kW 108 kW
KMP-F6-M2 1¼" 2.78 48 kW 65 kW 81 kW 97 kW 113 kW 129 kW
KMP-F10-M2 1½" 6.45 112 kW 150 kW 187 kW 225 kW 262 kW 300 kW
KMP-F15-M2 2" 7.65 133 kW 178 kW 222 kW 267 kW 312 kW 356 kW
KMP-F25-M2 DN65 16.1 280 kW 375 kW 468 kW 560 kW 654 kW 748 kW
KMP-F40-M2 DN80 27.8 485 kW 648 kW 808 kW 970 kW 1.13 MW 1.29 MW
KMP-F60-M2 DN100 53.3 930 kW 1.24 MW 1.55 MW 1.86 MW 2.18 MW 2.49 MW
KMP-F150-M2 DN150 165 2.86 MW 3.81 MW 4.77 MW 5.74 MW 6.67 MW 7.65 MW

The qt column indicates the flow at which the system's total head loss is 1mWc (10kPa).
Subsequent columns show the maximum capacity at select degrees of media cooling.


KMP-F: use of an existing heat meter

Where the utility has installed a Kamstrup energy calculator MULTICAL®601/602 or MULTICAL®801 this may - utility permitting - be used as part of a DH leakage protection system (KMP-Fxx-M1).

If the energy meter is sized so that Qmax exceeds qt for the relevant size flow meter, the energy calculator may not be used, as the resulting total system head loss will exceed 1mWc (10kPa).

If the Qmax of the energy calculator exceeds qt and the energy calculator is nonetheless employed in a leakage protection system, it is the responsibility of consultant or utility to demonstrate that the heating requirement of the installation may be met on the coldest day of the year with the prevailing operating conditions.

Note that the utility specifies operating contditions in the street or possibly in the branch (i.e. outside of the utility meter), and that the head loss in the flow meter(s) used by the energy calculator must be referred to the leakage protection system.

Where the energy calculator can not be used, the leakage protection system is sized only for the design target (KMP-Fxx-M2). In extreme cases, the resulting system may be up to two dimensions larger than the utility meter.

Where the utiliy has installed an energy calculator with two flow meters, system KMP-Fxx-M0 is used. If the meter load exceeds qt, the leakage protection should be selected one or two dimensions larger than the flow meters, making their head loss dominant, and placing responsibility for any comfort problems squarely with the utility. This strategy has no negative impact on system sensitivity, which is basically determined by the MULTICAL® energy calculator.