How to control heating parameters of the building?
HOW TO CONTROL HEATING PARAMETERS OF THE BUILDING?
During heating season in spring and fall, when outdoor temperature is from -10С to +80С, the heating utilities have no technical opportunity to control (reduce) heat supply. For most cities of Ukraine, this period makes up to 50-60% of total heating season duration. Thus, our buildings are overheated, and we open windows and waste expensive heat and our money.
But with the increase of gas prices and a significant increase in tariffs for heat energy, the issues of weather-based local control of heat carrier parameters at the building inlet became very important. Especially because economic consumption of energy is an important step to Ukraine's energy independence.
How we can ensure control of heating parameters in our buildings? The answer is simple: an individual heat sub-station should be installed in the building.
What is an individual heat sub-station? Individual heat sub-station is a complex engineering equipment required for connection of internal heat consumption systems to external heating networks.
Individual heat sub-station is usually located in the basement after the heating pipes inlet in the building. Individual heat sub-station equipment is owned by the heat energy consumers, which means it is common property of the building residents, i.e. of us.
What is the purpose of an individual heat sub-station? Individual heat sub-station can ensure the following convenience in the building:
1. Intense heat emission from heating appliances (in simple language – hot radiators) to feel comfortable and cozy;
2. Possibility of hydraulic and thermal control of the heating system elements (i.e., control of quantity and temperature of the heat carrier – hot water – going through the pipes and radiators attached to them, again, to create comfortable conditions in the premises);
3. Instrumental metering of consumed heat by the meters (so that we could pay not for mythical square meters, but for the amount of consumed heat);
4. Required quality of water in the system (so that it does not soil the pipes and radiators in the heating system and contains no malignant bacteria);
5. Control over heat carrier parameters at the system inlet (its compliance with temperature and pressure regulations);
6. High-quality control of heat supplied to the building depending on outdoor temperature, solar exposure, indoor temperature selected by the consumer etc. (so that we do not open window when it is already warm outdoors but the radiators are so hot you cannot touch them).
And, as you already guess, all this will lead to saving of heat energy and, correspondingly, to reduction of payment for it.
Why individual heat sub-stations do not perform their functions in many buildings? Individual heat sub-stations in the majority of buildings of mass construction period (1970s-1980s) are in non-operating state, they cannot perform their functions.
Typical individual heat sub-station scheme of that time had to include the heat meter. However, installation of heat meters was optional and most of the buildings never had them. That is why metering and payments for consumed heat are conducted not according to actual meter readings, but according to the norms based on the heating space size.
Lack of the instruments for pressure and temperature measurement (manometers and thermometers) makes it impossible to control parameters of the heat carrier at the building inlet.
Typical individual heat sub-station must have a device for mixing of return water from the heating system to hot heat carrier of the heating networks for controlling its temperature. Unfortunately, this device – elevator – often is not operating or does not exist at all. Therefore, the main control device in outdated individual heat sub-stations were damper valves (although the standards do not allow to use them as control valves), which leads to their rapid breakdowns, as well as hydraulic and thermal imbalance of the heating system.
Modern automated heat unit with weather-based control
The necessity of heat control caused appearance of automated individual heat sub-stations with weather-based control.Difference of these individual heat sub-stations from their predecessors is that mixing of return water and hot heat carrier from the heating networks is conducted by the water pump with electric control in automated mode, depending on the readings of the outdoor and indoor temperature sensors.
Depending on the weather conditions, the consumer may select the temperature chart for heat supply and thus control the amount of heat supplied to the building.
What are the benefits of installation of automated individual heat sub-stations with weather-based control? Individual heat sub-station reduces expenses for natural gas by 8-10% due to weather-based control and elimination of "overheating" during the transitional period (according to building codes DBN V.2.5-39 and DBN V.2.5-67, connection of heating systems to the heat sources should be conducted through individual heat sub-stations with automated weather-based heat control). You can also reduce the supply of heat energy after heat insulation of the building envelope (walls, windows, roofs, etc.) without violating the hydraulic and thermal mode of the heating system.
What are the options for individual heat sub-station installation? For installation of a modern individual heat sub-station with automated heat control in a multi-apartment building, two technical solution are possible:
1. Installation of a prefabricated modular individual heat sub-station offered currently by many firms.
2. Reconstruction of the existing heat sub-station through fulfillment of work on element-by-element equipment installation.
Whatever option you choose, you will have to go through the following phases: receipt of technical specifications from the heating utility, project development, project approval, dismantling the existing heat sub-station, assembly work. The final phase is about acceptance of the individual heat sub-station by the heating utility and State Standardization authorities (when individual heat sub-station includes heat energy metering unit).
What is cost of installation of an automated individual heat sub-station? Cost of a modular individual heat sub-station (together with construction and installation work) can reach almost UAH 250,000. Reconstruction of the existing individual heat sub-station and element-by-element installation of new equipment is less expensive and has a number of advantages, including:
- possible use of optimal equipment – metering unit, controls, pumps, depending on peculiarities of the building (design engineer will make the choice for you on the stage of project development). This will allow to avoid procurement of expensive equipment parameters of which exceed the requirements, and procurement of unnecessary equipment which is part of modular units;
- possible equipment assembly in the conditions of non-capacious basements;
- use of the pipes and equipment installed at the existing individual heat sub-station (if this equipment is in proper condition);
- transparent formation of heat sub-station cost according to the design engineer budget estimate; and
- avoidance of excess payment as a result of obtaining “turn-key” services.
Here are simple calculations. Services of the design engineer will cost up to UAH 5,000. Cost of heat metering unit is about UAH 20,000. Circulation pump can be purchased at UAH 7,000. Cost of the controls and sensors will be about UAH 10,000. Valves and fittings will cost UAH 10,000-11,000. Coupled with the installation works, cost of the pipelines, and services for obtaining specifications and approvals, installation of an individual heat sub-station through reconstruction of the existing one can be fulfilled at UAH 110,000-120,000 for an 80-apartment building (as of today).
Installation of individual heat sub-station must be made after preparation of the necessary design and estimate documentation. Note also that during operation of the automated individual heat sub-station it is necessary to carry out its maintenance, which can cost about UAH 500-600 per month (with accumulation of funds for calibration of the meters). But with such maintenance, individual heat sub-stations will serve long and faithfully.
What is payback period for installation of an individual heat sub-station?
We have calculated for you that for a five-story 80-apartment building with expected 290 kW heat load for heating and annual heat consumption for heating of about 550-600 Gcal (630-690 MW∙h) during the heating period, amount of annual heat energy savings can be up to 60-67 Gcal. As cost of 1 Gcal from 1 April 2015 is UAH 537.2/Gcal, and with VAT – UAH 644/Gcal, installation of the individual heat sub-station will give economic effect of UAH 38,700-43,200. Then its payback period will be 2.5-3.1 years. Even an expensive modular individual heat sub-station will pay off in less than 6 years.
Installation of individual heat sub-stations must be accompanied by other energy efficiency measures, that allow to reduce heat supply to the house and to lower payment for it.
According to statistics, insulation of external walls of buildings alone accounts for about 35% reduction of the total annual heat consumption, and insulation of the building envelope together with installation of an individual heat sub-station – 60% (windows – 5%, walls – 30%, upper floors – 10%, basement – 4%, individual heat sub-station – 11%).
If you want to live in comfort, be an economic owner and help your country become an energy efficient country – join those who have already installed individual heat sub-stations in their buildings!
Create the “climate” in your home yourself!