Issue 1/1996

Measurements in 29 houses in the locality of Petrovice showed increased values of radon volumetric activity (even more than 1 000 Bq/m3) and high concentrations of light ions at the same time. Along with that, there was no evidence of increase in lung cancer inci­dence. The authors suggest hypothesis of atmospheric ions' protective effect against radon. They explain this phenomenon by lungs self-cleaning ability enhancement resulting from the inhalation of high-ionised air. An epidemiological study which could qualify the relationship between rise in lung cancer incidence and exposure to radon, taking into account smoking habits will be finished in 1996.

High operational costs of the vast majority of bui/dings are mentioned. The procedures and principles to be considered in selection, design and realisation of additionallagging of bui/dings are specified. Basic methods of thermal insulation are characterised.

An old gas boiler plant was reconstructed in Prague within the framework of PHARE project. The plant was, among others, equipped with high-tech boilers with condensation of flue gases. The aim of the project was to prove the possibility of fuel saving through the use of condensation boilers linked up with an oldish (and, to a certain extent overdesigned) heating system of seven-storeyed block of flats. The housing estate Podbělohorská was selected for the task. There are nine identical buildings, each equipped with its own boiler plant. Thus, the evaluation of attained outcomes will be feasible at the end of the project.

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Rising prices of heat supply through central heating of flats resulted not only in technical arrangements improving the quality of heating systems but also, in introducing of heat consumption measurement. Annual heat consumption calculated by the designer is the primary data source for this task. However, behaviour of dwellers should be considered in heating and control system because the basic heat loss calculation and heater design correspond with relevant standards and thus are elaborated for the limit conditions. Two basic ways of heat costs calculation are proposed for buildings with and without heat consumption measurement.

Boilers and heaters utilising steam condensation heat from the flue gases produce con­densates of different pH factor (e.g. oil boilers - pH 3.7 to 5.5). That makes some heavy demands on flue-gas exhaust as discussed in the text. Suitable examples are included.

Water solubility of air is reduced by rising temperature and/or lowering pressure. Incompletely or wrongly deaerated heating system has shorter life-time. Heat supply to aerated radiators fails and thermostatic valves in such system can be excessively noisy. A method of calculation giving the volume of absorbed and released air is presented as well as rules of proper deaeration.

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