Calculation of heat losses in heating networks

Above ground laying
(single-pipe sections, separate supply and return pipelines)

Hours of work per year Laying Pipeline and laying method

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Underground laying
(two-pipe sections)

L section, m
tw °C
annual average
Hours of work per year Laying Material pipes Insulation
PU foam

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Calculation of heat losses in heating networks based on the methodology given in СНиП 2.04.14 Thermal insulation of equipment and pipelines.

The method of calculating heat losses is suitable for all pipelines covered by СНиП 2.04.14, except for systems with a subzero temperature of the working environment.

The amount of heat loss was calculated based on the normative density of the heat flow through the insulated surface of the pipeline. The methodology uses tabular data of specific heat losses from one meter of pipe, which are given in СНіП. Heat losses for pipe diameters and coolant temperatures not listed in the tables are determined by interpolation and extrapolation methods.

Estimated heat loss through pipelines of the heat network is determined by the formula:

Q = q · l · k · b

q – the specific normative value of heat loss from one meter of the pipe, W/m, at the average temperature of the hot-water and the given number of hours of operation per year, is determined for each of the diameters according to the tabular data СНиП 2.04.14;

k – the coefficient that takes into account additional heat losses from pipeline supports and shut-off valves is taken according to tabular data;

b – he coefficient that takes into account the change in heat flow density through the thermal insulation layer made of polyurethane foam (PU foam) is determined by СНіП 2.04.14;

l – length of the pipeline section, m.

The temperature of the hot-water to calculate heat losses in heat networks should be taken:

  • the average temperature of the hot-water for the year — for continuously operating networks;
  • the average temperature of the hot-water during the period with the average daily temperature of the outside air is lower 8°С — for heat networks operating only during the heating period.

Calculated temperatures in two-pipe water heating networks with quality regulation depending on Temperature curve of the heating system:

Temperature curve of the heating system Calculated temperatures
за ДБН В.2.5-39
Thermal networks
Calculated temperatures
по СНіП 2.04.14
Thermal insulation
180-70 supply 110°C
return 50°C
supply 110°C
return 50°C
150-70 supply 90°C
return 50°C
supply 90°C
return 50°C
130-70 supply 65°C
return 50°C
95-70 supply 55°C
return 50°C
supply 65°C
return 50°C
80-50 supply 45°C
return 50°C

In heat networks with quantitative regulation, when calculating heat losses, the maximum temperature in the supply pipeline is used, and in the return 50°C.

This calculation does not reflect the actual heat loss through the pipelines, but only determines the normative value, which should not be exceeded, if the thickness of the thermal insulation was selected in accordance with the specified СНіП.

Calculation of actual heat losses from pipes

Calculation of heat losses in the heat network

Sample calculation of heat losses in the heat network

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