BS 1264-4:2021 pdf download – Water based surface embedded heating and cooling systems Part 4: Installation
During the screed laying process, the screed material should contain only those additives approved by the manufacturer/supplier.
Do not use admixtures which entrain more than 5 % air into the screed to avoid loss of strength. Laying
When laying the screed, the temperature of the screed and the temperature of the room shall not fall below 5 °C. Subsequently, it shall be maintained at a temperature of at least 5 °C for the curing period. In addition, the screed shall be protected against drying-out and following this, against harmful effects, e.g. warmth and draught, in order to keep shrinkage low. Generally, this is ensured for smaller buildings when the building is closed.
NOTE Typically, the curing period is maintained for at least 3 days. Asphalt screed can be laid with temperature till 0 °C. Holes in floor Each hole in floor shall have been performed before the floor heating is installed in order to avoid any drilling thereafter. Tubes damage
If pipes of the radiant system are damaged, it is possible to restore the installation by connecting or joining the pipes, eliminating the damaged part. The fitting, which may be of metal or plastic, shall be adequately protected from mechanical forces or chemical corrosion by the elements that are in contact. A new pressure test of the system shall be carried out, in order to prevent and avoid hydraulic losses. The note of the intervention carried out with the precise location of the repair point of the pipes shall be reported on the plan of the project.
4.2.3 Leak test
The leak test may be performed using water or compressed air. Before installing the screed, the heating and cooling circuits shall be checked for leaks by means of a pressure test. For standard systems, the test pressure shall be 4 bar to 6 bar. When testing with air, the test pressure shall be 2 bar to 3 bar.
NOTE National standards and regulations can require lower test pressures. A maximum pressure loss of 0,2 bar/h shall be respected. In the case of asphalt screed, during the laying process, the pipes have to be depressurized.
For all type of screed during screed installation the pressure of tubes shall be returned to the operating one. The absence of leaks and the test pressure shall be specified in a test record. When there is a danger of freezing, suitable measures such as the use of frost protective or the conditioning of the building shall be taken. When normal system operation begins, any frost protection fluids may be drained and disposed of in compliance with National Health and Safety Regulations, then flushed 3 times with clean water.
4.2.4 Initial heating up of the emission system The purpose of the initial heating up is to check the function of the emission system and to bring it to operation.
The stability of the screed (e.g. cracks) can be seen after cooling down. As reported in Figure 2, this operation should be carried out on completed cement screeds after 21 days have elapsed, or for completed calcium sulfate screeds a period of 7 days shall elapse, or for asphalt screed 1 day shall elapse. For all screed materials, the specifications of the manufacturer shall be followed.
Cement and anhydrite screeds shall be heated before the floor coverings are laid. Work shall not begin until the above mentioned time frames have elapsed, depending on the screed types and the manufacturer’s instructions. The initial heat-up phase starts with an inlet temperature of 25 °C, which shall be maintained for 3 days. Subsequently, the maximum design temperature shall be set and maintained for at least another 4 days. Before the normal operation of the system begins, discharge and rinse of the system should be done according to national regulations. In case there are no national regulations the manufacturer’s instructions should be followed.