MHS Boilers Alpha Jetstream MD, Installation And User Manual

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Water The system design must ensure a flow rate consistant with the output of the boiler at
Circulation a temperature rise not normally exceeding 20ºC (25ºC Max).
System Due to the Jetstream technology employed in the boiler, the boiler may be operated at
continuous low return water temperatures without condensation and without the need for
back-end temperature protection measures, providing the minimum temperature limits
detailed in the technical data are observed. This allows variable flow temperatures to be
utilised (direct-on-boiler weather compensation) without the need for variable temperature
mixing valves. This simplifies the installation and ensures peak operational efficiency from
the boiler.
Should the system be operated at temperatures below than those mentioned above,
then a thermostatically controlled pumped by-pass (shunt pump) should installed
between the flow and return pipes to raise the temperature of the return water.
This is particularly important when firing with gas because of the higher dewpoint
temperature of gas products of combustion.
Water levels should be checked regularly and any leakages corrected in order to keep
system water make-up to a minimum, because excessive make-up will lead to scale
deposits forming in the boiler waterways causing local overheating and damage to the
boiler sections. Where there is doubt as to the quantity of water make-up, a water meter
should be fitted. If a system is known to lose water continuously, or be heavily
contaminated with dirt or sludge, then consideration should be given to installing a plate
type heat exchanger to separate the boiler from the damaging effects of the old system.
Boiler water systems should be thoroughly flushed and cleaned before a new boiler is
installed and system water should be treated with a scale and corrosion inhibitor
and best practise observed. The system should include strainers and consideration should
be given to fitting sludge traps if conditions warrant them.
The system can be either open vented or pressurised.The system must be fitted with
appropriately sized safety relief valve, reference to BS5410 Part2 or BS6644 will give
Safety of guidance on selection.If the system is open vented then an appropriately sized open pipe
water must be installed from the flow pipe adjacent to the boiler to run by the shortest possible
circulation direct route to terminate over the feed and expansion cistern. The boiler flow and return
system pipes should be fitted with isolation valves taking care to ensure that the safety relief
valve is installed onto the flow pipe between the boiler flow connection and the flow
isolation valve.
An altitude guage should be installed onto the flow pipe at the same level as the top of
of the boiler and marked with the minimum water level/pressure following first filling
of the system.
In the case of a sealed and pressurised heating system, an appropriately sized and
charged expansion vessel should be installed in conjunction with an automatic
water make up unit (pressurisation unit).
Filling the System . Non Domestic (other than in-house) fluid category 4
For category 4 systems, the approved method of filling must comprise the following
components arranged as shown: Control valve on the mains cold water pipework,
Strainer,Verifiable backflow prevention device with Reduced Pressure Zone (RPZ valve)
incorporating a type BA air gap, Tundish, Control valve on heating system.
PREPARATIONS BEFORE ASSEMBLY