MHS Boilers Ultramax WM 100, Operating & Maintenance Manual, Page: 16 / 50

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191007
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sensitive. The boiler can be switched on and off using the on/off switch on the control panel.
The installer should use a 2-pole main isolating switch with a contact opening of at least 3 mm in
the supply circuit to the boiler. With this, the entire boiler (including the boiler supply pump relay)
can be rendered volt free for maintenance work or in the case of failure.
In order to prevent faults due to electromagnetic fields, a screened cable should be used for
the bus connection and for all sensor and control signals between the boiler and all external
connection units. The screening should be connected on both sides according to the EMC
Directives.
Controls and options
The boilers are equipped with a modulating control system. The temperature can be controlled via
a 0-5 Vdc signal for example in response to external temperatures. If the voltage falls below 1 volt
the boiler reverts to the set point set on parameter P1. A hot water priority circuit also forms part
of the standard equipment, an additional sensor is required. Other options available on the boiler
can be supplied to extend this.
Ultramax WM Boiler Range
0-5 Control Signal Interpretation.
Constant Temperature zone = Controller P1 Temperature Set Point
The three following options are available:
BM8
A weather-dependent temperature controller with the following features:
- Programming of 3 heating periods with different room temperatures
- Adjustable night time boiler flow temperature reduction operation
- Choice between 2 weekly programmes
- Hot water priority circuit with 2 heat up periods
- Override for single hot water period during night time reduced flow temperature operation
- Optimum start time calculation
- Room temperature control with or without external temperature influence
- Option of internal (standard) or external room sensor (option)
- Adjustable response of the flow temperature to sensed room temperature