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ARENA 30 A
∆
t setting
The thermal head ∆t, that is the difference in heating water
temperature between the central heating outlet and return, can be
set by varying the speed of the pump system (Fig. 21- A). Note that
an increase in speed corresponds to a reduction of the ∆t, and vice-
A
versa. The curve of flow rate/ head of the standard pump is shown
in Chapter 1.
To fully exploit the advantages of condensation, the central heating
return inlet should work at low temperatures, possibly below
45-50 °C. The boiler will also work correctly at higher return
temperatures, but in this case the temperature of the flue gas outlet
is near to or above the dew point, with consequent reductions in
condensation.
One specific feature of the ARENA boiler is the possibility to work
with high ∆t, up to 50°C. This feature can be exploited to maintain
a low central heating return inlet temperature even when the
required outlet temperature is high, and thus allow the appliance to
operate in full condensation mode.
Fig. 21
Bypass setting
The boiler is fitted with a bypass between the outlet and return,
which guarantees minimum circulation inside the appliance even
with systems fitted with full-closing thermostatic zone valves. To
adjust the bypass, use a screwdriver on the adjustment cock,
operating from the bottom of the boiler
Adjusting the hydraulic system pressure
The fill pressure with the system cold, read on the boiler hydrometer "B", must be around 1.5 bar. If the
system pressure falls during operation (caused by the evaporation of the gases dissolved in the water) to
values below the minimum described above, reset the initial value. For correct boiler operation, the pressure
inside, when hot, must be around 2 – 2.5 bar.
B
Fig. 22
27
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