23
3.2 Heating System Layout
Components for the heating system must be chosen and installed in accordance with accepted engineering standards.
It is recommended to use detachable connections and corresponding shut-off elements in the heating system. During
boiler installation pay attention to the installation of the feed pipes.
In case of a conventional boiler installation the return flow temperature should be higher than 45 °C for gas firing and
higher than 30 °C for oil firing.
If this return flow temperature is regularly fallen short of, we recommend the installation of a by-pass pump (Fig. 3.4).
The minimum flows for by-pass and heating circulation pumps can be approx. determined as follows:
The boiler must be fitted with a type approved safety valve, in accordance with TRD 721.
Nominal thermal output (kW)
70
Min. pump flow of by-pass pump (m
3
/h) =
11,6
Nominal thermal output (kW)
Min. pump flow of heating pump at
Δ
T=10K (m
3
/h) =
Nominal thermal output (kW)
23,2
Min. pump flow of heating pump at
Δ
T=20K (m
3
/h) =
Fig. 3.4 Traditional boiler installation
with elevated return
Dibo-
Accu-
mulator
VL Heating feed flow
RL Heating return flow
HK Heating circuit
AG Expansion vessel
HPHeating pump
LPAccumulator charge
pump
SF Accumulator sensor
BPBy-pass pump
1 Breather
2 Safety valve
3 Pressure gauge
4 Check valve
5 Discharge
