Increasing Comfort in a Residential Building, Prague Czech Republic
The project was renovating a residential building in Prague, Czech Republic. The building is a twelve-storey building containing 100 apartments.
The project was renovating a residential building in Prague, Czech Republic. The building is a twelve-storey building containing 100 apartments. The renovation project was implemented by Mr Václav Pilát, the project designer, Alltech, the installing company and IMI with the balancing know-how and suitable products
The Project
The project was renovating a residential building in Prague, Czech Republic. The building is a twelve-storey building containing 100 apartments. The building was insulated entirely (facade, roof, cellar ceilings) and has had its windows replaced. The heating of the building is managed by hot water using a two-pipe heating system. The heat source for the building is a pressure-independent heat exchanger station connected to the central heat supply with a total heating capacity of 229 kW. The exchanger station is equipped with an equithermal control. The renovation project was implemented by Mr Václav Pilát, the project designer, Alltech, the installing company and IMI with the balancing know-how and suitable products.
The Hydronic Challenge
There are 316 radiators installed in the building, mostly of old column type. All heating elements in the building were fitted with thermostatic valves, radiator fittings and thermostatic heads of different manufacturers and different designs. However, all these thermostatic valves and heads in the building are beyond their useful life.
The system was divided into 25 risers connected to a horizontal distribution running from the heat exchanger station on the 1st floor. The risers were fitted with a balancing valve and a differential pressure controller. The parameters to which the heel control was balanced have yet to be discovered. The parameters of the balancing at the building base were still being determined.
The Solution
The renovation project’s first steps were calculating the heat loss of every room in this insulated building, flow rates and settings for new thermostatic valves, state hydraulic losses, and balancing. Furthermore, it was necessary to adjust the temperature gradient of the building (equithermal regulation) to the insulated state of the building.
Another step was to install new thermostatic valves with AFC technology and thermostatic heads by IMI Heimeier. As the original size of the building base didn´t fit the new building parameters, it was replaced with a new balancing valve STAD and the differential pressure controller STAP by IMI TA. All pipework remained without any changes.
Project Parameters
With AFC technology, the Eclipse F thermostatic valves provide flow balancing for every radiator. The riser dP control helps with the authority of the thermostatic valves and ensures the quiet operation of the heating system. Room temperature control is provided by the Heimeier thermostatic head K fitted to the radiator valve. The presetting of the thermostatic valves is based on the project documentation.
The circulating pump for heating water flow is a part of the exchanger station. It covers both the pressure loss of the exchanger station and the pressure loss of the building system. The minimum pressure loss of the complete system was determined by a pressure loss calculation of 50 kPa.
Installing thermostatic valves requires a change in the technological procedure of valve replacement. Thermostatic valves can no longer be changed randomly in the system according to the wishes and schedules of the apartment owners. Still, replacing the valves in the entire system is always necessary. The maximum flow control of the AFC technology must be considered when designing the project documentation. Technically speaking, valves with AFC technology will not allow higher flow into the radiator than what is set, even if part of the thermostatic valves in the riser is closed. Thermostatic valves with AFC technology must have a sufficient disposition pressure (10 - 15 kPa, see technical documentation for the valve); otherwise, the flow through the valve is lower than set.
After the installation, it was necessary to balance the heating system and set the operating point of the circulation pump in the heating exchanger station. At first, the thermostatic valves were set up according to the project documentation with special keys supplied by IMI. Using a special tool, the optimum circulator conveying height was stated using measurements on Eclipse F reference thermostatic valves. The resulting set transport height on the circulator was 6.5 m, and the pump control was fixed to constant pressure.