For systems with underfloor heating and piping which is permeable to
oxygen, system separation must be used between the heat generator
and other system parts which are at risk of corrosion.
Heating systems in which a Potterton condensing boiler is to be installed
must be designed as a closed heating system with diaphragm
expansion vessel in accordance with DIN EN 12828.
Directly connecting a Potterton heat generator to an "open" heating
system is not permitted. System separation must also be used here. In
"open" systems, the connection to the outdoor air causes oxygen to be
absorbed in such a quantity that it leads to corrosion in the heating
system. Furthermore, the objective of consistent energy savings is not
achieved due to the additional heat loss via the "open" expansion
vessel. Gravity systems with an "open" expansion vessel are not in line
with current technology.
5.5
Heating water requirements
Caution
Note the requirement for the heating water quality.
Requirements regarding heating water quality have increased in
recent times as system conditions have changed:
Reduced heat demand.
Use of cascades in larger buildings.
Increased use of buffer cylinders in combination with solar
thermal energy and solid fuel boilers.
Power-generating heating systems.
Storage tank charging systems and similar.
The focus is always on designing systems that are guaranteed to
operate reliably throughout their service life without any faults.
The following requirements apply to the heating water quality in the entire
circuit, based on VDI directive 2035 Sheets 1 and 2. In the case of
renovation measures, it is not sufficient to merely fill partial sections
according to VDI 2035.
The pH of the heating water must be between 8.2 and 9.0 during
operation. A corrosion inhibitor can be added to the heating water. The
manufacturer specifications must be complied with.
The water must not contain any foreign substances, such as beads of
sweat, rust particles, scale, sludge or other sedimenting substances.
During commissioning, flush the system until only clean water runs out.
When flushing the system, ensure that water does not flow through the
heat exchanger in the heat generator, that the radiator thermostats are
removed and that the valve inserts are set to the maximum flow rate.
Generally speaking, the quality of drinking water is adequate, but a check
must be performed to ensure that the drinking water available in the
system is suitable for filling the system in terms of its hardness and water
constituents (see
water hardness diagram
). If this is not the case, various
measures are possible.
5 Before installation
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