On-Site Thermal Diagnostics Of Heating And Dhw Installations

S t r e s z c z e n i e W ustawie o charakterystyce energetycznej budynków wprowadzono wymagania dotyczące przeprowadzania kontroli instalacji ogrzewczych. Diagnostyka cieplna instalacji grzewczych jest to ocena stanu technicznego systemów ogrzewania i c.w.u. ze względu na sprawność energetyczną i niezawodność uzyskania wymaganych warunków cieplnych w budynku oraz pokrycia potrzeb użytkowników w zakresie ciepłej wody użytkowej. Dane uzyskane z diagnostyki są przydatne dla właściwej, energooszczędnej eksploatacji instalacji, sporządzania charakterystyki energetycznej budynku oraz wykonania audytu energetycznego budynku na potrzeby termomodernizacji. W artykule opisano metodykę kompleksowej inspekcji i diagnostyki cieplnej instalacji ogrzewania i ciepłej wody użytkowej, oraz wyszczególniono zakres podstawowych działań, które powinny być wykonane podczas diagnostyki. Przedstawiono również praktyczne wykorzystanie diagnostyki w kilku budynkach. K e y w o r d s : Heating system; Hot water; Inspection; System efficiency; Thermal diagnostics. 2/2017 A R C H I T E C T U R E C I V I L E N G I N E E R I N G E N V I R O N M E N T 165 A R C H I T E C T U R E C I V I L E N G I N E E R I N G E N V I R O N M E N T The Si les ian Univers i ty of Technology No. 2/2017 A . S p e c j a ł , H . C i u m a n 166 A R C H I T E C T U R E C I V I L E N G I N E E R I N G E N V I R O N M E N T 3/2015 out in a building for the purpose of: • verification of the proper performance, equipment and maintenance of the heating system to ensure optimum energy efficiency, • estimation of the actual energy efficiency of the system, • providing recommendations for the energy efficiency improvements of the system. The inspection is carried out based on a local vision in the building using the following sources: building and installation design documentation, operation and maintenance data, facility book, previous inspection reports, fuel and energy bills and also information provided by the building administrator. In Standard [3] inspection procedures are described in a general way. Formulas of the reports from the inspection are included in Regulation [4]. The detailed method for diagnostics of heating and DHW systems is not described neither in legal or statutory requirements. Such a diagnostics was the part of Strategic Research Project (described in [5]) which included also the diagnostics of air-conditioning systems [6], heating and cooling sources [7]. The results of the measurements obtained during comprehensive diagnostics were used to determine the energy performance of the buildings [8-12]. The methodology of diagnostics of heating and DHW systems was described in the guidebook [13] and tested in several buildings [14]. During diagnostics of installations it is also necessary to check the correct operation of installations and their individual components as well as the compliance of the applied solutions with the technical requirements [2]. Assessment of the technical conditions is the basis for the estimation of energy efficiency and allows to formulate recommendations on the opportunities in order to improve performance and ensure optimum operation conditions. The possibility of delivery the design heat load of the building and the thermal power for hot water preparation by the heat source is verified during the diagnostics of heat sources. This paper does not include diagnostics and methods for determining the efficiency of heat generation systems (heat sources and storages) for heating and hot water installations. 2. STAGES OF THERMAL DIAGNOSTICS OF HEATING AND DHW SYSTEMS The diagnosis of heating and hot water systems includes the following stages: a. identification of the system in order to determine any differences and deviations from the design state, b.checking the quality of system operation, the maintenance of system and devices, the correctness of location and operation of measuring and control devices, c. inspection of heating and DHW distribution of subsystems, d.inspection of space heating emission and control sub-system. 3. TASKS AND ACTIONS CARRIED OUT WITHIN THE FRAMEWORK OF DIAGNOSTICS OF HEATING AND DHW SYSTEMS Many problems related to the operation of installations should be identified for the assessment of efficiency of existing heating and hot water installations. Appropriate actions should be taken in order to determine the optimal operating conditions of the installation and to formulate recommendations on the possibility of improving the energetic efficiency. An important purpose of energy diagnostics of the DHW system is also estimation of the amount of hot water used in the building. Such a value is useful for the assessment of correct installation operation and determination of the consumption of final energy required for hot water preparation in the building. The main problems which should be identified and actions that should be undertaken in order to properly diagnose central heating system and DHW installation are presented in the Tables 1 and 2. O N S I T E T H E R M A L D I A G N O S T I C S O F H E A T I N G A N D D H W I N S T A L L A T I O N S E N V I R O N M E N T 3 /2015 A R C H I T E C T U R E C I V I L E N G I N E E R I N G E N V I R O N M E N T 167 Table 1. Tasks and actions carried out within the framework of diagnostics of the central heating installation e Task Description of the action 1 Carrying out a survey among users of a diagnosed building to get a general answer to the question: The survey should be conducted during the heating season when the outdoor air temperature is low as this is a period of a potential malfunction of the system. 2 Verification of compatibility design and actual radiators' power; checking whether the installation was modernized after any changes in the building envelope (verification of the selection of the proper nominal parameters of the heating medium). The degree of oversize of the radiators should be checked when the building envelope has been insulated, when the system of settlements of individual heating costs based on heat cost allocators is used in the building; in this case neglecting of radiators oversizing generate errors in the division of heating costs; the best way to correct the power of radiators after thermal modernization of the building is to replace them with new ones of a lower power. 3 Verification of the location of the radiators and whether they are correctly installed; identification of radiators' covers. Determining the influence of verified factors on the total efficiency of the heat emission in the room space (using tables A.1÷A.8. from Standard [15]). 4 Check whether or not the correct automatic control of the installation has been applied. Verification of compliance of used devices with the technical requirements [2] and their settings. 5 Inspection whether or not proper temperature sensors, control valves and controls are properly applied and installed. Checking whether the measuring devices allow control the parameters on the manifolds and on the branches of the installation; verification of control valves' settings with design documentation. 6 Verification of the hydraulic balancing of the installation. Checking the method of balancing and setting values of balancing valves (verification with the documentation), especially if the building envelope was modernized. 7 Verification of types of thermostatic radiator valves and selection of their settings. If the valves are installed before the thermal insulation of the building envelope, check that the valve settings have been changed after the thermomodernization (whether the documentation of the hydraulic regulation of the installation after the thermo-modernization exists). 8 Evaluation of place and method of installation of thermostatic valves; possible covering of the valve heads influence the increased heat consumption. Determining the impact of existing solutions on the total efficiency of the heat emission in the room space. 9 Evaluation of the operating conditions for thermostatic valves. Verify that the balancing valves are used in the system and which are the operating parameters of the pump. 10 Evaluation of pumps used in the installation. Description of the type of pumps, how they are controlled, check the operating parameters of the pumps: are they in accordance with the design assumptions? 11 Checking the division of the installation into zones (branches). In the case of a large installation, it should be noted whether the appropriate zones of the installation are separated; parts of the building with a different way of use or with significantly different heat gains should be supplied with separate branches of the installation. Checking the operation of the controls and settings of the control valves in the individual zones of the system. 12 Verification of the venting of the heating installation, checking the technical condition of the automatic air vents. Description of the real state and presentation of the effects of improper solutions (possibility of too low temperature in premises). 13 Verification of method of preventing against excessive pressure in the installation. Checking the volume of the expansion vessel and the pressure in the device, checking the safety valve setting; presentation of possible threats. 14 Checking the level of contamination of the installation by sediments and assessment of technical condition of filters; whether the appropriate cleaning devices are installed, and whether they are properly operated. a. selection of places for measuring the thickness of limescale, b. measurement of sediment layers in pipelines using a thickness gauge, c. description of an existing sediment layers and what should be done (the chemical cleaning or replacement of pipelines), d. description of the type and technical requirements of the cleaning equipment. A . S p e c j a ł , H . C i u m a n 168 A R C H I T E C T U R E C I V I L E N G I N E E R I N G E N V I R O