Design and Requirements for Installing Heat Energy Commercial Metering Units and Heat Controls - Municipal Energy Reform Project in Ukraine (MERP)

Design and Requirements for Installing Heat Energy Commercial Metering Units and Heat Controls

Energy metering units and/or heat controls are installed and commissioned under a project designed and approved according to the design norms. The project is designed to identify the specific technical and engineering solutions, estimate the construction cost and fulfillment of the construction and assembly works (detailed drawings).

The design of the heat energy metering unit and heat controls must be performed as a single-phase working project. The design is grounded on the design assignment (technical specifications and terms of reference) as well as basic data to be provided to the designer by the construction customer before the beginning of the design works.

The contents, procedure of development, coordination and approval of the design documentation for the heat energy metering unit are defined by the current regulatory documents on design in construction.

The design documents for the metering unit consist of the following sections:

1. Explanatory note that includes:

title page;
details of the designer and customer of the project;
basic data for design – this section presents systematized information (provided by the construction customer and received as a result of an engineering survey) on the thermal and hydraulic characteristics of the heat consumption system or the heating network for which the heat energy metering unit is aimed;
brief description of the grounds for the design and list of values to be calculated via the metering (amount of heat energy, maximum and average heat carrier consumption over a certain period of time, average temperature of heat carrier over certain period of time, immediate values of heat carrier pressure in the feed and return pipes);
brief characteristics of the object, including a brief description of the architectural and planning characteristics of the building or premises in the building in which the equipment and pipes of the heat energy metering unit are planned to be located; and
engineering calculation data – this section must contain calculation formulas, present the results of hydraulic calculations of the heat energy metering unit and calculation of heat losses in the pipes from the location of a balance sheet property division (operational responsibility, division point) to the projected location of the metering point. A hydraulic calculation is performed in order to identify the estimated heat carrier consumption as well as a survey of the influence of the hydraulic resistance of the pipe fittings and devices of the heat energy metering unit on the operational regime of the heat consumption system (heating network). The results of the hydraulic calculation are the basis for identifying the conditional (nominal) sizes of the equipment and parts of the pipe in the heat energy metering unit. The results of the calculation of heat losses may be used in the future in commercial settlements between the heat energy supplier and consumer.

2. Drawings, which include:

list of general data with a list of all project pages and references to regulatory documents and materials used;
schematics of the principal solutions of the heating and electrical sections as well as the measurement and control devices;
equipment and materials specification; and
estimate documents.

In case of a small project amount, parts of the drawing may be combined in the explanatory note.

On request of the customer of design work, other sections and/or types of research work may be included in the project.

The “Basic Data for Designing” section of the project documentation must include at least the following data:

location of the balance sheet property division (operational responsibility) or division point between the heating utility and the consumer;
projected location of the point of sale (consumption) of heat energy;
type of the heating system (closed water, open water, steam system);
estimated heat load of the heat consumption system (heating network) in the projected metering point;
technological characteristics of the central or local control of heat energy supply in the heat consumption system (heating network);
available and projected for the heat consumption system (heating network) values of heat carrier pressure in the feed and return pipe of the heat consumption system (heating network) in the metering point; and
nominal sizes of pipes and pipe fittings which are actually available as of the moment of design in the point where the equipment of the heat energy metering unit will be installed.

During the preparation of the heat energy metering unit engineering equipment document, the designer must include the following elements in the construction of the metering unit:

1) devices measuring the amount of heat energy consumed by the heat consumption system or heating network in order to use data received as a result of measurements for commercial calculations. This element is mandatory for the metering unit construction;

2) devices measuring the heat supply quality indicators (average heat carrier temperature over the indicated period of time in the feed and return pipe, heat carrier pressure, pressure difference in the feed and return pipes or the derivative values, difference in heat carrier masses that passed through the feed and return pipes during the calculation period) based upon data received as a result of measurements in commercial calculations. This element should be included in the metering unit construction upon request of the project customer;

3) controlling measurement devices aimed at measuring immediate heat carrier parameters (pressure and temperature) – for maintaining heat carrier parameters. This element is mandatory for the metering unit construction;

4) pipe fittings aimed at the quick and reliable disconnection of equipment and pipes of the metering unit from the heating network and/or heat consumption system, discharging of heat carrier and air escape from the pipes – to the ensure safe and efficient operation of the heat energy metering unit. This element is mandatory for the metering unit construction;

5) heat carrier purification devices to ensure the metrological characteristics of the metering unit. These elements are mandatory for the metering unit construction.

During the selection of engineering equipment for the heat energy metering unit, it is necessary to ensure the fulfillment of the following requirements:

for the heat energy metering unit, the measurement devices need to be selected from the types included in the State Register of Measurement Instruments, or those measurement devices which passed the State Metrological Certification;
the range of measurement of the measurement devices (upper limit of temperature range (pressure scale), lower limit of temperature scale (pressure scale), upper limit of temperature difference (pressure differential), lower limit of temperature difference (pressure differential), upper limit of consumption, lower limit of consumption, upper limit of heat capacity) should comply with the range of changes in value of heat carrier parameters in the metering point. It is necessary to ensure the ability to use the identified measurement devices when the system is operating under automated control of the heat energy amount sold or consumed;
mechanical (strength) characteristics of the measurement devices, pipe fittings, means of protection from soiling, straight pipes, their connections and connecting instruments (conditional pressure, maximum operational temperature) must correspond to the operational pressure and operational temperature of the heat carrier for the heat consumption system (heating network);
operational characteristics of the measurement devices must ensure the proper functioning of these devices with an average time to failure of at least 10,000 hours and an average life of at least 8 years;
operational characteristics of the pipe fittings and means of protection from soiling must ensure the proper functioning of the fittings and means with an average time to failure of at least 30,000 hours and an average life of at least 20 years;
pipe fittings must be built in before and after the places that meters are installed, a water drain valve must be included in the lowest point, and an air discharge valve in the highest pipe point of the metering unit;
nominal diameters of pipe fittings must be defined upon the condition of the most efficient correlation between the cost of the fittings and pressure losses in them, with the calculated heat carrier consumption; and
to equip the heat energy metering unit, it is necessary to provide a convenient premises protected from unauthorized access and with reliable waterproofing and lighting sufficient for taking meter readings.

While developing the solution regarding the engineering equipment of the heat energy metering unit, it is necessary to proceed from the technical data and to take into account the requirements and recommendations on the assembly of the measurement devices, pipe fittings, means of protection from soiling and pipe connecting elements mentioned in the service documents of manufacturers' and normative documents on the design and operation of the heating networks and heat consumption systems.