ARCA MK 100, Руководство пользователя

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6.3 REDUCED OUTPUT RUNNING
The reduced output running of MK and PRK boilers can be successfully used during autumn and spring and
when the system runs partially.
To obtain it extract all the metal spiral coils from ducts.
This operation results in an increasing in smoke temperature so that it is necessary to reduce the burner
capacity of about 30%.
In this way you have an output decreasing without having an efficiency decreasing.
Always control the smoke temperature is not lower than 180°C and not higher than 220°C. The reduced output
running is profitable also during summer in case of combined boilers.
It is better to tailor the fuel capacity to the system thermal need. A high number of burner ignitions
damage the boiler.
6.4 BOILER WATER TEMPERATURE
The heating system water temperature is to be adjusted according to the room thermal need by acting on:
a) the burner
b) the boiler thermostat
c) the mixing valve
The latter represents the better way to do it because it allows a high boiler temperature even when the heating
system water temperature is low. In this way you have a good protection against corrosion and the boiler will
run longer.
The return water has never to be lower than:
−
45°C using gas, light or heavy oil with a sulphur percentage lower than 1%,
−
50°C using heavy oil with a sulphur percentage higher than 1%.
Under these limits, smokes can reach their condensation point and build up sulphur acid compounds on the
smoke duct surface. In this way the duct bundle can be damaged.
6.5 SYSTEM IGNITION
The possible opening of cold secondary circuits during the boiler running has to be carried out step by step.
It is advisable to control the circulating pump by means of a thermostat installed in the boiler switchboard (see
page 10).
6.6 BOILER THERMOSTAT SET VALUES
Operating thermostat set values must be established according to heating system specifications.
In case there is a mixing valve and a circulating pump, the operating thermostat can be set at 85-90°C to avoid
return temperatures lower than the values shown in the paragraph 6.4.