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2.4.4 Heating circuits
Several heating circuits:
The total consumed output is not allowed to exceed the nominal thermal output of the boiler. In-line regulating
valves must be installed to permit better regulation of the system. In a building without insulation (new build-
ing, not yet plastered) the calculated and actually required heating requirements often differ to a considerable
extent.
Minimum heat consumption:
It must be possible for the smallest possible boiler output must be continuously dissipated from the boiler dur-
ing operation (see technical data in section 4.4.). Alongside an accumulator tank of a sufficient size, suitable meas-
ures for
minimum heat consumption
(e.g. never completely closing the manual mixing valve, “consumer cir-
cuit” or radiators that cannot be blocked off, not all radiators fitted with thermostatic valves) must be guaranteed
in each phase of operation.
Having a correctly sized accumulator tank is essential for correct operation.
Mixer valve:
A 3-way mixer valve is always necessary; in conjunction with outside temperature control, there must be a 3-
way motorised mixing valve and an accumulator tank.
Underfloor heating:
Possible with an accumulator tank (with outside temperature control, motorised mixing valve).
Return flow temperature increase:
This is necessary in all systems with an accumulator tank and in old systems with a large volume of water (>
200 l). It is essential for the temperature of the return flow to be kept to at least 45 °C during heating, otherwise
the temperature of the return flow must be increased using a mixing pump or valve.
In order to achieve good temperature stratification in the accumulator tank, we recommend setting the boiler
circuit to a 15-20 K differential by means of the return hold-up group SK RH or SK RH 54. See the enclosed instruc-
tions for the return hold-up group for guidance values for the setting.
Boiler start-up relief:
A boiler start-up relief must be installed and connected in all cases so that the circulation pump(s) are switched
off when the boiler temperature is below 60 °C. This prevents condensation forming in the boiler and extends
its service life.
A boiler start-up relief of this kind is contained in the MES control system.
2.4.5 Heating water
a) The chemical composition of the heating water must meet the specifications of ÖNORM H 5195 Part 1 or VDE
2035 P1. According to ÖNORM M 5195 Part 1, the condition of the heating water must be checked every 2
years by a heating technician in order to avoid corrosion and sediment accumulation in the heating system.
The check must be performed once every year in heating systems with more than 1500 litres of heating water.
For the Installer
“Komfort” Pufferspeicher: Won’t open in tag editor “Comfort” accumulator tank
In this case, the size of the accumulator tank is based on the long-term heat output, i.e. how long the customer
wants to heat from the accumulator tank. The boiler output does not depend on the heating requirements of the
building, but on the filling chamber size of the boiler and how often the customer wants to replenish fuel to
bring the accumulator tank up to temperature.
A
sensible precaution
for a buffer solution of this kind is a
low temperature heating circuit design (< 35 °C)
.
