MHS Boilers Ultramax 115, Operating & Maintenance Manual, Page: 34 / 46

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011204 34
6 Operating instructions
6 .1 Function
When a heating demand is received and before the boiler starts up, the appliance must be prepurged.
The fan supplies combustion air and has a modulating control.
A zero controller in the gas valve determines the required quantity of gas.
Gas and air are optimally mixed.
Thereafter, the gas air mixture is ignited on the main burner.
The fan also ensures that the resulting flue gasses are subsequently removed.
The removal system for these gasses performs an essential function for the proper operation of the
appliance.
The unit has no limits for return water temperature. If this temperature is low, condensation will
be formed which will then be removed via the drainage system.
6 .2 Regulation
Depending on the heating demand, the unit will be started up and shut down between 0% and
20% capacity and will be continuously modulated between 20% and 100% capacity.
6.3 Control module
Lid closed Lid open
1 Function 1 Parameter indication
standby P1 current/setting boiler supply temp.
automatic operation P2 current/setting domestic hot water
summer operation temperature
service operation *P3 desired temperature
2 Function selector P5 current external temperature
3 fault indication P8 current low velocity header temp.
4 supply temperature P9 current/maximum boiler capacity
5 malfunction code (flashing) P10 password entry for factory settings